The link to this thread is down. Does anyone know how to disable the auto power
off on the sk-1?

--- In CasioSK@yahoogroups.com, "plutoniq9" <Plutonique9@...> wrote:
>
> No, it is possible to remove the function with a modification...read this;
>
> http://s2.excoboard.com/exco/thread.php?forumid=55931&threadid=228175
>
> Because all SK's use the same CPU, they all can be modded in the same way.
>
> Good Luck
>
> Ryan
>
>
> --- In CasioSK@yahoogroups.com, "Joerg Zeitschel" <joerg@> wrote:
> >
> > --- In CasioSK@yahoogroups.com, "gmeredith1" <gmeredith1@> wrote:
> > >
> > > Is there anyone out there who knows of a mod to disable the auto
> > > shutoff that happens every 5-10 mins if no keys are played?
> > >
> > > Cheers, Graham
> > >
> >
> >
> >
> > Unfortunately there is no way to disable this function. You will read
> > about this in the SK-1 manual (see: http://www.aero-pack.de/power-
> > sk1.jpg). This problem persists also in the CT Series of Casio
> > Keyboards. Casio changed it with the modern keyboards like the WK-
> > series. There it IS possible to disable this function.
> >
> > Greetings
> >
> > Joerg
> > (Webmaster of CASIOLOGIE - http://casiologie.pro.tc)
> >
>

Metal film and polyester? - no difference in this circuit - if they're easier to
get use them. Around where I am, polyester greencaps are really cheap and in
every shop, so that's the only reason I used them. Tne metal film ones will work
fine. So just choose the ones that are the same value or close to as the ones
specified in the guide and it will be fine.

I can understand how easy it is to make a mistake on this board - I made several
when I built it. I kind of regret making it so small, except that it fits inside
the SK so nicely without having to remove the speaker. Best to always build one
module at a time and test it before bulding the next one.

Cheers, Graham



--- In CasioSK@yahoogroups.com, "jeanbender@..." <lofideadbeat@...> wrote:
>
> Thanks for yours anwers, i made a small mystake in my wirings...
>
> Could you explain me what are differencies between metal film and polyester
film capacitors ? Can i use the first ones instead of the others ??
>
> I'm looking for buying these caps but there are so much differents ones that
i'm lost...
>
> Thansk for all !
>
>
> --- In CasioSK@yahoogroups.com, "gmeredith1" <gmeredith1@> wrote:
> >
> > You have an SK-8, ok then that makes it easier to troubleshoot for me.
> >
> > I have my ground and +V taken from where it is in the PPB guide.
> >
> > Are you wiring up your power for the +7.5V form the track side of the board
or the component side? If its from the component side, make sure it actually is
the same point as in the guide, which shows the point from the track side.
> >
> > The other thing is that there will still be some residual power in that 7.5V
audio power line for a while after the power switches off - it won't go down to
zero for quite a few minutes until all the capacitors along the power line
discharge. I think I measured typically 2-3V residual voltage for a while after
power off. You may have been measuring this.
> >
> > The ltc1799 is for a pitch bend circuit, is that correct? It probably will
still run the ltc1799 for a while after you power down because of the residual
voltage, and since it probably uses a tiny current draw will still operate. But
that's OK - it won't matter, so long as the 7.5V power rail does in fact drop
when power is switched off. The ltc1799 will eventually suck the power out of
the residual capacitors.
> > Be assured that it won't drain your batteries if you hook it up to the point
mentioned while powered down - unlike if you hook it up to a +5V rail in the SK
- I found that out the hard way when I was making the PPB early on in the
piece!!
> >
> > Cheers, Graham
> >
> >
> >
> >
> > --- In CasioSK@yahoogroups.com, "jeanbender@" <lofideadbeat@> wrote:
> > >
> > > Oh, i'm working on a sk8... Well, i maybe made a mystake, i will fix it
tomorrow. But i'm sure that i take the v+ from the LA 1438' power input pin . I
should take the grounds one from this, too...
> > >
> > > Well, i will see and give you more informations !!
> > >
> > > thanks for your answer !
> > > deadbeat
> > >
> >
>

Thanks for yours anwers, i made a small mystake in my wirings...

Could you explain me what are differencies between metal film and polyester film
capacitors ? Can i use the first ones instead of the others ??

I'm looking for buying these caps but there are so much differents ones that i'm
lost...

Thansk for all !


--- In CasioSK@yahoogroups.com, "gmeredith1" <gmeredith1@...> wrote:
>
> You have an SK-8, ok then that makes it easier to troubleshoot for me.
>
> I have my ground and +V taken from where it is in the PPB guide.
>
> Are you wiring up your power for the +7.5V form the track side of the board or
the component side? If its from the component side, make sure it actually is the
same point as in the guide, which shows the point from the track side.
>
> The other thing is that there will still be some residual power in that 7.5V
audio power line for a while after the power switches off - it won't go down to
zero for quite a few minutes until all the capacitors along the power line
discharge. I think I measured typically 2-3V residual voltage for a while after
power off. You may have been measuring this.
>
> The ltc1799 is for a pitch bend circuit, is that correct? It probably will
still run the ltc1799 for a while after you power down because of the residual
voltage, and since it probably uses a tiny current draw will still operate. But
that's OK - it won't matter, so long as the 7.5V power rail does in fact drop
when power is switched off. The ltc1799 will eventually suck the power out of
the residual capacitors.
> Be assured that it won't drain your batteries if you hook it up to the point
mentioned while powered down - unlike if you hook it up to a +5V rail in the SK
- I found that out the hard way when I was making the PPB early on in the
piece!!
>
> Cheers, Graham
>
>
>
>
> --- In CasioSK@yahoogroups.com, "jeanbender@" <lofideadbeat@> wrote:
> >
> > Oh, i'm working on a sk8... Well, i maybe made a mystake, i will fix it
tomorrow. But i'm sure that i take the v+ from the LA 1438' power input pin . I
should take the grounds one from this, too...
> >
> > Well, i will see and give you more informations !!
> >
> > thanks for your answer !
> > deadbeat
> >
>

You have an SK-8, ok then that makes it easier to troubleshoot for me.

I have my ground and +V taken from where it is in the PPB guide.

Are you wiring up your power for the +7.5V form the track side of the board or
the component side? If its from the component side, make sure it actually is the
same point as in the guide, which shows the point from the track side.

The other thing is that there will still be some residual power in that 7.5V
audio power line for a while after the power switches off - it won't go down to
zero for quite a few minutes until all the capacitors along the power line
discharge. I think I measured typically 2-3V residual voltage for a while after
power off. You may have been measuring this.

The ltc1799 is for a pitch bend circuit, is that correct? It probably will still
run the ltc1799 for a while after you power down because of the residual
voltage, and since it probably uses a tiny current draw will still operate. But
that's OK - it won't matter, so long as the 7.5V power rail does in fact drop
when power is switched off. The ltc1799 will eventually suck the power out of
the residual capacitors.
Be assured that it won't drain your batteries if you hook it up to the point
mentioned while powered down - unlike if you hook it up to a +5V rail in the SK
- I found that out the hard way when I was making the PPB early on in the
piece!!

Cheers, Graham




--- In CasioSK@yahoogroups.com, "jeanbender@..." <lofideadbeat@...> wrote:
>
> Oh, i'm working on a sk8... Well, i maybe made a mystake, i will fix it
tomorrow. But i'm sure that i take the v+ from the LA 1438' power input pin . I
should take the grounds one from this, too...
>
> Well, i will see and give you more informations !!
>
> thanks for your answer !
> deadbeat
>

Oh, i'm working on a sk8... Well, i maybe made a mystake, i will fix it
tomorrow. But i'm sure that i take the v+ from the LA 1438' power input pin . I
should take the grounds one from this, too...

Well, i will see and give you more informations !!

thanks for your answer !
deadbeat

The PPB guide was written for an SK-8. I presume your running an SK-1? The power
tap point will be different in the SK-1. You will need to check with a
multimeter the point where the audio power rail is - the power rail that runs
the speaker amplifier - as this powers down when switched off.

The SK-1 schematics in the service manual show this point - P28 of the service
manual. The power input pin to IC1 (the LA4138 power amp chip) is an ideal point
- measure all the pins voltage on the chip while powered up and you'll find it -
it wil be around 7.5V DC. Make sure when you measure that your black negative
multimeter probe is placed on the negative battery terminal as your ground
point. From there you can measure back from the chip to any convenient soldering
point that measures 7.5V DC, and stops when powered off.

Cheers, Graham


--- In CasioSK@yahoogroups.com, "jeanbender@..." <lofideadbeat@...> wrote:
>
> Ok thanks you helped me a lot with this tip, and you helped me knowing
something else... and that's great !!
>
> I've got another question now... Wher can i find a place which could shut down
power connections used for my ltc1799 and the PPB ?? THe place which is showed
in the ppb schematics seems to be powered even if my sk is down...
>
> Thanks !
>

Ok thanks you helped me a lot with this tip, and you helped me knowing something
else... and that's great !!

I've got another question now... Wher can i find a place which could shut down
power connections used for my ltc1799 and the PPB ?? THe place which is showed
in the ppb schematics seems to be powered even if my sk is down...

Thanks !

Greencap capacitors are also called polyester film non-polar capacitors. They
are commonly green but also come in red. blue and other colours. They can be
found anywhere - Radio Shack, Jameco, Farnell, Digikey, Newark, RS Electronics,
Mouser Electronics.

Here is an example:

<http://australia.rs-online.com/web/search/searchBrowseAction.html?method=getPro\
duct&R=6224612>

Cheers, graham




--- In CasioSK@yahoogroups.com, "jeanbender@..." <lofideadbeat@...> wrote:
>
> Hi everybody !!
>
> I'm new on this group, but i've already bent and done some circuit bent stuff
( http://virb.com/dead_beat ).
>
> Well; i'm going to bend my sk8, and i'd really like to had the phat filter
bank, but i don't know where i could find greencaps capacitors...
>
> Can i use something else ? If not where can i buy them ??
>
> Thanks for any answer !
>
> See ya soon !
>

Hi everybody !!

I'm new on this group, but i've already bent and done some circuit bent stuff (
http://virb.com/dead_beat ).

Well; i'm going to bend my sk8, and i'd really like to had the phat filter bank,
but i don't know where i could find greencaps capacitors...

Can i use something else ? If not where can i buy them ??

Thanks for any answer !

See ya soon !

hello all. i'm jamie, new here. i am new to the circuit bending scene. i have
had some success bending a cheap HMP-139 keyboard, as well as unlocking some
sounds in one of those baby's crib heartbeat simulators (i figured how to turn
it into somewhat of a drum machine!).

that said, i am curious about the realistic concertmate series by radioshack. i
know some of these were made by casio, as the CM500 was an sk1.

what casio model was the concertmate 300?

to take the question one step further, is there a site, or at least a chart
listing all concertmate keyboards and their casio parallels?

thanks.

-jamie

You solved the hum issue, that's great! My workaround for this, now that I know
what caused yours to hum, is to install rechargeable batteries in it (probably
not in this one, as it's not yours, but when you do get one of those wrecked
SK's you got going). But what you do is put a 2nd power socket in the SK - one
that goes directly to the battery terminals in the SK casing, rather than hooked
up to the stock power socket (the stock power socket disconnects the batteries
when you plug in an adapter).

You then charge the batteries and also RUN the SK off this socket - forget about
the stock one. The batteries act like a huge smoothing capacitor for the AC
power pack and reduce the hum to almost zero when you're using the power pack,
and they also are getting charged in the process. I use some 2000mAH NIMH AA's
in my SK-8 and they last for weeks on a single charge and plenty of use - I use
6 of them instead of the normal 5 in the SK, the 6th is mounted inside the SK,
as the NIMH batteries arent 1.5V - they're 1.25V, so the 6th one takes it to
7.2V total which is cose enough to the stock 7.5V battery voltage.

I loved the video - it sounds great!! The sounds on the SK1 are different to the
SK8, so it's good to hear the PPB on some different stock sounds. I seem to
recall people saying the SK1 was a more versatile synth sampler than the SK8
because you can put effects and envelopes on the stock sounds, not just the
samples, or something like that. Is that the case? if so, then on the SK1
there's probably not such a need for the Slo-AD mod like there is on the SK8,
which you can't vary the stock sounds on.

Hey, what did you connect the LED's to - the CV lines or the data lines? If you
hook some up to the CV lines the LEDs should follow the sound envelope, haven't
tried it though.

Anyhoo, glad you go it all happening - well done, the PPB is a difficult board
to get right!

Cheers, graham



--- In CasioSK@yahoogroups.com, "luke" <icanfeelmyselfrotting@...> wrote:
>
> I tried the Slo-Ad and it's great. Unfortunately, I didn't have the space to
include this mod. I had to use center-off switches to get the most out of the
added bends. If only I had the quad-gangs.
> Still, I love the mods I installed.
> This SK1 is actually for a friend, so I can always add the extras to my own
personal SK :)
> It was a cool arrangement. In return for modding her SK1, I got 3 heavily
abused, broken keyed SK1's... ripe for recasing and expanding!!!
>
> Anyway, I've recorded a video and I'll have it up on Youtube in an hour or
two.
> You'll have to excuse my terrible playing though.
> Just search 'wrongbot' and 'phat philter' and it should come up with the
video.
>
> oh yeah, the hum was from the adaptor. With batteries, she's more or less free
from background noise. WOO.
>
> Thanks again for your help.
> Luke
>
> --- In CasioSK@yahoogroups.com, "gmeredith1" <gmeredith1@> wrote:
> >
> > Hey Luke, that's great news! Glad you liked it. It really turns the SK into
a synthesizer, doesn't it!
> >
> > For the next mod, you really gotta try my "Slo-AD mod" - for a variable
attack and decay on the sounds. Add this effect to the PPB and it really does
sound like a full blown synth. The preset sounds become completely different
instruments. And it's really simple and easy to do - much much simpler than the
PPB. The plans are in the FILES section here.
> >
> > Cheers, graham
> >
> >
> >
> > --- In CasioSK@yahoogroups.com, "luke" <icanfeelmyselfrotting@> wrote:
> > >
> > > Hey Graham.
> > > It's finished!!!
> > > I've not got any fresh batteries at the mo to test the PPB. It works well
enough with an adaptor. The hum is only overpowering when the cut-off pots are
fully juiced & when the CV input is in use.
> > > I'll get a recording done at some point over this weekend.
> > >
> > > I hooked the audio out into the internal amp with success. There is a bit
of a pop when it's swithched on/off, but it's not that bad.
> > >
> > > Again, thanks for the help.
> > > It's a beautiful mod that I need to add to everything now!!!!
> > >
> > > Luke
> > >
> > > --- In CasioSK@yahoogroups.com, "gmeredith1" <gmeredith1@> wrote:
> > > >
> > > > Haha, well, I always think it's better to feel like a dumbass and have a
working keyboard than the other way around!
> > > >
> > > > Regarding the insert point, yes, it is just before the volume slider and
amplifier circuit. On the SK-8, there is a wire link that you can cut and
connect the PPB output to the volume control and amp side of the link. I'm
almost certain that there will be a similar link in the SK-1.
> > > >
> > > > I also put in a PPB bypass switch that used the other side of the link
(the normal SK output side) and used it to toggle between it and the PPB out.
Very useful. In the PPB guide it shows this at the very end of the guide.
> > > >
> > > > I've been thinking about your hum problem. After trying it with
batteries and if you still get it, I wonder if it is a ground loop with the PPB,
SK-1 and your amp? Try disconnecting the ground wire to the amp input from the
PPB out. When you do install the PPB into the SK-1 circuit as mentioned above,
you don't need to use a ground wire - only the PPB signal out - as the ground is
already connected through the hooking up of the PPB to the power rails of the
SK-1.
> > > >
> > > > Maybe, after all else fails, that may work if you were hooking the PPB
directly up to an amp. OR, I suspect that the impedance of the output is all
wrong for certain amp inputs. Is the amp a line input, or a guitar input, or
mic? Line is best I think. Do you have to have the amp volume way down or way up
to get a good level?
> > > >
> > > > I'm pretty sure that when you hook it up internally to the internal SK
amp it will be better, even with a power pack connected.
> > > >
> > > > Also, just keep in mind that you may have to balance the output volume
of the PPB before the insert point, so that when you bypass it or switch it in,
the volume level is matched ok. To do this, you may have to explore along the
insert point circuit track at various places before or after resistors or caps
to get it right. Or maybe add a resistor to the PPB output if it's too hot, so
that it balances with the bypassed level. On the PPB guide for the SK8 I have
chosen the spot that does this, so I think the SK-1 will also have an optimal
spot.
> > > >
> > > > If you attach the PPB output wire to a multimeter probe (without the
multimeter), you can have the keyboard playing and use the probed-output to tap
along the SK amp line for this optimum spot. It works a treat for exploring
audio circuits and saves doing temporary soldering.
> > > >
> > > > Cheers, Graham
> > > >
> > > >
> > > >
> > > > --- In CasioSK@yahoogroups.com, "luke" <icanfeelmyselfrotting@> wrote:
> > > > >
> > > > > Hey Graham.
> > > > > Thanks for all the help thus far.
> > > > > the item number for the hex gang is; 290366887977
> > > > > Hongkongsuperseller is the traders name.
> > > > > They're very cheap.
> > > > >
> > > > > I'm just in the process of refitting the ppb. I cracked the first
replacement speaker panel so had to make a replacement replacement panel. Such
are the perils of perspex drilling.
> > > > >
> > > > > I reversed the APO mod and counted my keystrokes again and it still
cut off after roughly 400 strokes. I had a rhythm playing too and noticed the
notes interrupted the drums. Then I set the sk to 'play' instead of 'record' and
everything is now fine and I feel a bit of a chump :)
> > > > >
> > > > > The APO mod for the sk1 seems to leave all other functions intact, but
I don't think it allows the sk to turn off fully manually. I may return this
back to factory as it's probably surplus to my needs.
> > > > >
> > > > > To have the PPB going through the internal speaker, does it pass
through the volume slider to the power amp (LA4138)and then to the speaker?
> > > > >
> > > > > Thanks again.
> > > > > Luke
> > > > >
> > > > > --- In CasioSK@yahoogroups.com, "gmeredith1" <gmeredith1@> wrote:
> > > > > >
> > > > > > Hi Luke,
> > > > > >
> > > > > > I'm glad you resolved the hot 4th line, that's great! Perhaps when
you get time you could show the connect points for the SK1 in a photo or
something for those with an SK1.
> > > > > >
> > > > > > Regarding powering it, running it off the 7.5V amp line like you had
is the best place to run it for a number of reasons - the main one is that this
voltage line completely powers down when you switch the SK1 off, whereas the 5V
line is always on, even with the power turned off - to retain the processors
settings. On the SK8 it remains powered to also retain the 4 sample memories
when switched off. Hooking the PPB up to the 5V rail will cause the PPB to not
switch off and so drain your batteries whilst switched off.
> > > > > >
> > > > > > If you were running it off the power pack it might make the PPB hum
a little if the power pack is a bit rough in its AC smoothing. That's just a
guess - you could try running the SK-1 off batteries to see if this helps. If it
doesn't, try the pot wire shielding - it can only help. The other thing you
could do is try wrapping the whole PPB in foil, with a connection from the foil
to a ground point on the PPB board (Make sure you wrap the board in plastic wrap
first to insulate it from the foil). It's worth a try. Maybe you could email me
a mp3 of the hum whilst, say, playing a rhythm so I can see how much there is.
> > > > > >
> > > > > > The other hum source could be the SK1 circuit board itself - namely
the processor - being a computer, it emits electromagnetic radiation that can
interfere with unshielded audio circuits. Mine hummed more or less in certain
parts of the casing, even when running everything off batteries. Not much, and
only when turned up a lot, but you could hear that it was more than the SK1 by
itself. I seem to recall testing the PPB externally before fitting it, running
it off batteries and also the sk off batteries and hearing no hum - I only
noticed the hum when I finally mounted it in the casing and recalled not hearing
it before.
> > > > > >
> > > > > > The SK1 shutdown problem - I suspect it's related to the shutdown
mod. Try reversing the mod and put the SK back to stock condition and try it
first.
> > > > > >
> > > > > > I've never been totally convinced that this mod works on the SK-1.
On the SK-8, it is impossible to implement, because the SK-8 processor itself
will shut down after 7 mins even if you do the mod to it - I tried and tried and
bought the service manual and tried but to no avail. You can get the analog
section to stay awake, and everything LOOKS like its still awake, but the
proceesor goes to sleep and the keyboard becomes unresponsive even though all
the lights are on and you can hear hiss from the speaker. On the SK-8, this is
because the shutdown timer is built-in to the processor chip itself - it's not
an external device disabled by cutting a trace. And somehow, I think that the
SK-1 is the same, although i've heard of elusive reports saying that it does
work. But how much working? ALL functions, or only some?
> > > > > >
> > > > > > Hex-gang pots?? Have you got a link to the supplier? That sounds
interesting. The DIY-trimpot setup is woth doing but is a royal pain in the
arse. I stuffed up a couple of sets of trimpots before I got them working. I
DID, however, get an email from someone who was going to use a DIGITAL 4-gang
pot setup. This to me sounds like the best way of all - I'll look into it
sometime. Going digital means you can have as many "gangs" as you like, and
control them all simultaneously off a SINGLE analog pot - and all using a small
chip! I'll post a topic on the Circuitbenders.co.uk forum asking about them - I
think it was someone there who mentioned it.
> > > > > >
> > > > > > Keep it happening - let me know how you get on! The PPB is
definitely worth it!
> > > > > >
> > > > > > Cheers, Graham
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > > --- In CasioSK@yahoogroups.com, "luke" <icanfeelmyselfrotting@>
wrote:
> > > > > > >
> > > > > > > Hi Graham.
> > > > > > > Thanks for your numerous replies :)
> > > > > > > The PPB is great and I'm glad of it's size. If it were much
bigger, it just wouldn't fit into the sk1.
> > > > > > >
> > > > > > > I'm running the sk and PPB from an adaptor. It's set to 6volts but
puts out close to 8v. I've not tried with batteries as of yet but I'll give it a
whirl.
> > > > > > > I'm hoping to internally mount the PPB in the speaker cavity as it
is the most spacious and isolated area in the SK1.
> > > > > > >
> > > > > > > I need to replace some wires with shielded cable and tidy up the
under-board jumpers. Will shielding the cutoff pot wires be necessary?
> > > > > > >
> > > > > > > The output from the PPB is just hooked up to a jack socket and fed
into my mixer. I'd prefer to have it internally mixed but I'm unsure how to
achieve this.
> > > > > > >
> > > > > > > The 4th channel issue was solved. I had hooked it up to the point
labelled in the Files section. I measured the output with my multimeter and it
was 1-2v hotter than the other signals, so I connected it to a point closer to
the main IC and that fixed it :)
> > > > > > >
> > > > > > > I've disconnected the PPB entirely for further testing today.
> > > > > > > The SK only semi-shuts down. The drums can still be heard, but no
keyboard can be heard. This is aslo true without the PPB connected.
> > > > > > > I'm not overly sure if this particular SK was faulty before I
opened her up.
> > > > > > > I had the PPB wired to the 7.5 of the amp IC... perhaps this would
this cause more hum...
> > > > > > >
> > > > > > > I contemplated stacking trimpots for a crude 4-gang. I'm still
tempted. With the 5534s, the 2 dual gangs are a lot more usable than the 741s.
I've seen some hex-gang pots on ebay for cheap from China. They're triple-deck,
apparently and look like 3 dual-gang pots piggybacking. They're also cheap at £3
a pot.
> > > > > > > Cogs n' gears had crossed my mind, but I'm not sure I have the
skills or tools for the job. It would be beautiful though.
> > > > > > >
> > > > > > > Thanks for all your help and advice Graham. I'll post my results
soon.
> > > > > > > Cheers!
> > > > > > > Luke
> > > > > > >
> > > > > > > --- In CasioSK@yahoogroups.com, "gmeredith1" <gmeredith1@> wrote:
> > > > > > > >
> > > > > > > > Hi Luke,
> > > > > > > >
> > > > > > > > Graham here, the designer of the Phat philter Bank. Sorry I
missed your posts, gosh, I go away for a few days and this place gets exciting
:D
> > > > > > > >
> > > > > > > > Glad you got the PPB working, I apologise for making it so
cramped a board layout - I did this so I could mount the full quad board
internally without having to ditch the speaker. One day I'll do a larger, more
mistake-proof layout.
> > > > > > > >
> > > > > > > > Regarding the squeal - I found that the 741's did exactly that,
too - they are sensitive to the resonant point on the res pot much more than the
5534's. The 5534's are much cleaner sounding as well, so thy're better all
round. They are also more sensitive and have higher gain - and so they'll pick
up hum more than the 741.
> > > > > > > >
> > > > > > > > Mine does hum but only ever so slightly, and you only notice it
when you turn up the volume past half-way. Mine is mounted in an SK-8
internally. Are you running the SK on batteries or an AC plug pack? The AC plug
pack is possibly making the PPB hum, if you are. Try it on batteries and see if
it still does it.
> > > > > > > >
> > > > > > > > Is yours internally mounted or separate? Moving mine around
inside to various places created more/less hum. Make sure all your input/output
wires are shielded.
> > > > > > > >
> > > > > > > > Are you running the outputs of the PPB directly into an amp, or
re-routed back into the amp in the SK? Mine is re-routed to the SK amp.
> > > > > > > >
> > > > > > > > Try using it outside of the sk, if it isn't already, and see if
it changes the hum issue. At the worst case scenario, unhook it completely from
the sk and test it as a standalone filter, powered by it's own battery and test
each channel input for noise. Also, try mounting it inside a metal enclosure to
see if this shields it from hum.
> > > > > > > >
> > > > > > > > Regarding the 4th channel being louder than the others - I'm not
sure about it, but one of the SK lines might be a bit louder than the others.
Increase the PPB input resistor to that channel to balance it out with the
others is my suggestion.
> > > > > > > >
> > > > > > > > Regarding the sk shutting down, are you powering the PPB
directly off the sk, or from its own separate battery? It sounds like you've
connected it to the Sk internally at a certain place and it's draining the +5V
processor power rail and making it think that the batteries are flat. Is this
correct? The PPB best runs off the 7.5V audio power rail inside the SK, which is
separate from the proccesor power rail.
> > > > > > > >
> > > > > > > > Hope that helps, if nothing helps it, disconnect the PPB from
the SK completely and check it, and then reconnect it in stages, checking each
channel and the hum, and the power issue.
> > > > > > > >
> > > > > > > > Cheers, Graham
> > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > > > --- In CasioSK@yahoogroups.com, "luke" <icanfeelmyselfrotting@>
wrote:
> > > > > > > > >
> > > > > > > > > The keys cut out after approx. 400 strokes. Which is rubbish.
> > > > > > > > > Any advice on this one?
> > > > > > > > >
> > > > > > > > > On the PPB, I replaced the 741s with 5534s and it has cut the
squealing completely, I am now experiencing a great deal of hum instead, which
is as annoying as the squeal but not as deafening.
> > > > > > > > > I imagine it's a loose ground somewhere or some additional
caps are needed or something. The key issue is more vexing.
> > > > > > > > >
> > > > > > > > > Sorry for the double post btw.
> > > > > > > > > Luke
> > > > > > > > >
> > > > > > > > >
> > > > > > > > > --- In CasioSK@yahoogroups.com, "luke"
<icanfeelmyselfrotting@> wrote:
> > > > > > > > > >
> > > > > > > > > > There's an APO mod on Electri-Fire's site which works a
treat. I've had the demo going for about 20 minutes and the crazy is setting in
now...
> > > > > > > > > >
> > > > > > > > > > I don't think my issues are APO related.
> > > > > > > > > > What seems to be happening is the keyboard becomes
unresponsive after about 2-3 minutes of playing. If I up the volume, I can hear
some matrix noise, but no key sounds. The drums are still audible and hitting
the demo button brings the keys back to life. It's strange and annoying.
> > > > > > > > > >
> > > > > > > > > > You should try the PPB. It's really nice. Gives the SK1 a
whole new dimension. I think the layout could be made less cramped, but for
space saving GMeredith's layout is as packed as could be.
> > > > > > > > > >
> > > > > > > > > > I'll be putting an LTC1799 in too for pitchability.
> > > > > > > > > >
> > > > > > > > > > I'll chuck a vid up when she's finished.
> > > > > > > > > > Thanks again Tanner
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > > --- In CasioSK@yahoogroups.com, "noystois" <noystoise@>
wrote:
> > > > > > > > > > >
> > > > > > > > > > > i dont know, ive never built it. it only turns off 10
minutes after you last touched the sk1 right? not while youre still playing? ive
heard of people trying to modify the sleep circuit on the sk1 but with no
success. seems like all you would need to do is find a redundant i/o that resets
the sleep circuit and hook it up to an lfo or something. i've done this with
other toy keyboards but never an sk1. it might be kind of hard to find
considering you would have to wait 10 minutes to see if it even works. might be
worth it to try and overclock the sk1 so that the sleep circuit only takes like
1 minute or something. just some ideas. glad to hear you got the filter working
though.
> > > > > > > > > > >
> > > > > > > > > > > --- In CasioSK@yahoogroups.com, "luke"
<icanfeelmyselfrotting@> wrote:
> > > > > > > > > > > >
> > > > > > > > > > > > Thanks for that Tanner.
> > > > > > > > > > > > I actually found the source of the problem... I'd placed
all of the res pot wires after a trace cut instead of before it. A rookie
mistake indeed.
> > > > > > > > > > > > SO now I've relocated the wires and it works, but it's
still not great as the 4th module's signal is much hotter than the others.
> > > > > > > > > > > >
> > > > > > > > > > > > I just wish I had quad gang pots. I'm using 2 pairs of
dual gang and it's not ideal.
> > > > > > > > > > > >
> > > > > > > > > > > > Other than a few minor issues, the PPB is brilliant.
> > > > > > > > > > > >
> > > > > > > > > > > > One major problem I'm having is that the SK stops
working after about 10 minutes. The 'on' LED is still lit but no sound can be
made. Does the PPB affect the auto power off function, or is there a way to
disable the APO?
> > > > > > > > > > > >
> > > > > > > > > > > > Thanks again for the advice.
> > > > > > > > > > > > Luke
> > > > > > > > > > > >
> > > > > > > > > > > > --- In CasioSK@yahoogroups.com, "noystois" <noystoise@>
wrote:
> > > > > > > > > > > > >
> > > > > > > > > > > > > i dont think the values of those caps are too
critical, they will just change the tone of the filter. the first thing you
could try is adding a decoupling cap say 100mf from the positve power to the
ground. but i think what the real problem might be is that the signal coming in
is too high. you should try replacing the 470k resistor with a 100k pot with one
outer lug going to the .01mf cap, the other lug going to GND and the wiper going
to the signal. its hard for me to understand the stripboard layout but
fortunately i have the original schematic here. it says to set the cutoff all
the way up and the resonance all the way down and then adjust the volume to the
filter so that the output from the filter is only as loud as the original
signal. if you are still getting too much gain, there may be too much resistance
between the -in and the out but i doubt it, its only 200k. good luck. -tanner
> > > > > > > > > > > > >
> > > > > > > > > > > > > --- In CasioSK@yahoogroups.com, "luke"
<icanfeelmyselfrotting@> wrote:
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > I've just finished a phat Philter for my SK-1. It
seems to be working reasonably well. However, it squeals like crazy.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > I didn't have any NE5443AN op-amps, so I used 741s
instead. Could this be the root of the problem?
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Also, I had no 470pf caps so I used 560pf as an
alternative and have also tried 390pf, which alters the tone of the squeal but
does not remedy it completely.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Any ideas or thoughts would be greatly appreciated.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > I'm guessing that changing op-amps would probably be
the biggest help.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Luke
> > > > > > > > > > > > > >
> > > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > >
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
>

I tried the Slo-Ad and it's great. Unfortunately, I didn't have the space to
include this mod. I had to use center-off switches to get the most out of the
added bends. If only I had the quad-gangs.
Still, I love the mods I installed.
This SK1 is actually for a friend, so I can always add the extras to my own
personal SK :)
It was a cool arrangement. In return for modding her SK1, I got 3 heavily
abused, broken keyed SK1's... ripe for recasing and expanding!!!

Anyway, I've recorded a video and I'll have it up on Youtube in an hour or two.
You'll have to excuse my terrible playing though.
Just search 'wrongbot' and 'phat philter' and it should come up with the video.

oh yeah, the hum was from the adaptor. With batteries, she's more or less free
from background noise. WOO.

Thanks again for your help.
Luke

--- In CasioSK@yahoogroups.com, "gmeredith1" <gmeredith1@...> wrote:
>
> Hey Luke, that's great news! Glad you liked it. It really turns the SK into a
synthesizer, doesn't it!
>
> For the next mod, you really gotta try my "Slo-AD mod" - for a variable attack
and decay on the sounds. Add this effect to the PPB and it really does sound
like a full blown synth. The preset sounds become completely different
instruments. And it's really simple and easy to do - much much simpler than the
PPB. The plans are in the FILES section here.
>
> Cheers, graham
>
>
>
> --- In CasioSK@yahoogroups.com, "luke" <icanfeelmyselfrotting@> wrote:
> >
> > Hey Graham.
> > It's finished!!!
> > I've not got any fresh batteries at the mo to test the PPB. It works well
enough with an adaptor. The hum is only overpowering when the cut-off pots are
fully juiced & when the CV input is in use.
> > I'll get a recording done at some point over this weekend.
> >
> > I hooked the audio out into the internal amp with success. There is a bit of
a pop when it's swithched on/off, but it's not that bad.
> >
> > Again, thanks for the help.
> > It's a beautiful mod that I need to add to everything now!!!!
> >
> > Luke
> >
> > --- In CasioSK@yahoogroups.com, "gmeredith1" <gmeredith1@> wrote:
> > >
> > > Haha, well, I always think it's better to feel like a dumbass and have a
working keyboard than the other way around!
> > >
> > > Regarding the insert point, yes, it is just before the volume slider and
amplifier circuit. On the SK-8, there is a wire link that you can cut and
connect the PPB output to the volume control and amp side of the link. I'm
almost certain that there will be a similar link in the SK-1.
> > >
> > > I also put in a PPB bypass switch that used the other side of the link
(the normal SK output side) and used it to toggle between it and the PPB out.
Very useful. In the PPB guide it shows this at the very end of the guide.
> > >
> > > I've been thinking about your hum problem. After trying it with batteries
and if you still get it, I wonder if it is a ground loop with the PPB, SK-1 and
your amp? Try disconnecting the ground wire to the amp input from the PPB out.
When you do install the PPB into the SK-1 circuit as mentioned above, you don't
need to use a ground wire - only the PPB signal out - as the ground is already
connected through the hooking up of the PPB to the power rails of the SK-1.
> > >
> > > Maybe, after all else fails, that may work if you were hooking the PPB
directly up to an amp. OR, I suspect that the impedance of the output is all
wrong for certain amp inputs. Is the amp a line input, or a guitar input, or
mic? Line is best I think. Do you have to have the amp volume way down or way up
to get a good level?
> > >
> > > I'm pretty sure that when you hook it up internally to the internal SK amp
it will be better, even with a power pack connected.
> > >
> > > Also, just keep in mind that you may have to balance the output volume of
the PPB before the insert point, so that when you bypass it or switch it in, the
volume level is matched ok. To do this, you may have to explore along the insert
point circuit track at various places before or after resistors or caps to get
it right. Or maybe add a resistor to the PPB output if it's too hot, so that it
balances with the bypassed level. On the PPB guide for the SK8 I have chosen the
spot that does this, so I think the SK-1 will also have an optimal spot.
> > >
> > > If you attach the PPB output wire to a multimeter probe (without the
multimeter), you can have the keyboard playing and use the probed-output to tap
along the SK amp line for this optimum spot. It works a treat for exploring
audio circuits and saves doing temporary soldering.
> > >
> > > Cheers, Graham
> > >
> > >
> > >
> > > --- In CasioSK@yahoogroups.com, "luke" <icanfeelmyselfrotting@> wrote:
> > > >
> > > > Hey Graham.
> > > > Thanks for all the help thus far.
> > > > the item number for the hex gang is; 290366887977
> > > > Hongkongsuperseller is the traders name.
> > > > They're very cheap.
> > > >
> > > > I'm just in the process of refitting the ppb. I cracked the first
replacement speaker panel so had to make a replacement replacement panel. Such
are the perils of perspex drilling.
> > > >
> > > > I reversed the APO mod and counted my keystrokes again and it still cut
off after roughly 400 strokes. I had a rhythm playing too and noticed the notes
interrupted the drums. Then I set the sk to 'play' instead of 'record' and
everything is now fine and I feel a bit of a chump :)
> > > >
> > > > The APO mod for the sk1 seems to leave all other functions intact, but I
don't think it allows the sk to turn off fully manually. I may return this back
to factory as it's probably surplus to my needs.
> > > >
> > > > To have the PPB going through the internal speaker, does it pass through
the volume slider to the power amp (LA4138)and then to the speaker?
> > > >
> > > > Thanks again.
> > > > Luke
> > > >
> > > > --- In CasioSK@yahoogroups.com, "gmeredith1" <gmeredith1@> wrote:
> > > > >
> > > > > Hi Luke,
> > > > >
> > > > > I'm glad you resolved the hot 4th line, that's great! Perhaps when you
get time you could show the connect points for the SK1 in a photo or something
for those with an SK1.
> > > > >
> > > > > Regarding powering it, running it off the 7.5V amp line like you had
is the best place to run it for a number of reasons - the main one is that this
voltage line completely powers down when you switch the SK1 off, whereas the 5V
line is always on, even with the power turned off - to retain the processors
settings. On the SK8 it remains powered to also retain the 4 sample memories
when switched off. Hooking the PPB up to the 5V rail will cause the PPB to not
switch off and so drain your batteries whilst switched off.
> > > > >
> > > > > If you were running it off the power pack it might make the PPB hum a
little if the power pack is a bit rough in its AC smoothing. That's just a guess
- you could try running the SK-1 off batteries to see if this helps. If it
doesn't, try the pot wire shielding - it can only help. The other thing you
could do is try wrapping the whole PPB in foil, with a connection from the foil
to a ground point on the PPB board (Make sure you wrap the board in plastic wrap
first to insulate it from the foil). It's worth a try. Maybe you could email me
a mp3 of the hum whilst, say, playing a rhythm so I can see how much there is.
> > > > >
> > > > > The other hum source could be the SK1 circuit board itself - namely
the processor - being a computer, it emits electromagnetic radiation that can
interfere with unshielded audio circuits. Mine hummed more or less in certain
parts of the casing, even when running everything off batteries. Not much, and
only when turned up a lot, but you could hear that it was more than the SK1 by
itself. I seem to recall testing the PPB externally before fitting it, running
it off batteries and also the sk off batteries and hearing no hum - I only
noticed the hum when I finally mounted it in the casing and recalled not hearing
it before.
> > > > >
> > > > > The SK1 shutdown problem - I suspect it's related to the shutdown mod.
Try reversing the mod and put the SK back to stock condition and try it first.
> > > > >
> > > > > I've never been totally convinced that this mod works on the SK-1. On
the SK-8, it is impossible to implement, because the SK-8 processor itself will
shut down after 7 mins even if you do the mod to it - I tried and tried and
bought the service manual and tried but to no avail. You can get the analog
section to stay awake, and everything LOOKS like its still awake, but the
proceesor goes to sleep and the keyboard becomes unresponsive even though all
the lights are on and you can hear hiss from the speaker. On the SK-8, this is
because the shutdown timer is built-in to the processor chip itself - it's not
an external device disabled by cutting a trace. And somehow, I think that the
SK-1 is the same, although i've heard of elusive reports saying that it does
work. But how much working? ALL functions, or only some?
> > > > >
> > > > > Hex-gang pots?? Have you got a link to the supplier? That sounds
interesting. The DIY-trimpot setup is woth doing but is a royal pain in the
arse. I stuffed up a couple of sets of trimpots before I got them working. I
DID, however, get an email from someone who was going to use a DIGITAL 4-gang
pot setup. This to me sounds like the best way of all - I'll look into it
sometime. Going digital means you can have as many "gangs" as you like, and
control them all simultaneously off a SINGLE analog pot - and all using a small
chip! I'll post a topic on the Circuitbenders.co.uk forum asking about them - I
think it was someone there who mentioned it.
> > > > >
> > > > > Keep it happening - let me know how you get on! The PPB is definitely
worth it!
> > > > >
> > > > > Cheers, Graham
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > --- In CasioSK@yahoogroups.com, "luke" <icanfeelmyselfrotting@> wrote:
> > > > > >
> > > > > > Hi Graham.
> > > > > > Thanks for your numerous replies :)
> > > > > > The PPB is great and I'm glad of it's size. If it were much bigger,
it just wouldn't fit into the sk1.
> > > > > >
> > > > > > I'm running the sk and PPB from an adaptor. It's set to 6volts but
puts out close to 8v. I've not tried with batteries as of yet but I'll give it a
whirl.
> > > > > > I'm hoping to internally mount the PPB in the speaker cavity as it
is the most spacious and isolated area in the SK1.
> > > > > >
> > > > > > I need to replace some wires with shielded cable and tidy up the
under-board jumpers. Will shielding the cutoff pot wires be necessary?
> > > > > >
> > > > > > The output from the PPB is just hooked up to a jack socket and fed
into my mixer. I'd prefer to have it internally mixed but I'm unsure how to
achieve this.
> > > > > >
> > > > > > The 4th channel issue was solved. I had hooked it up to the point
labelled in the Files section. I measured the output with my multimeter and it
was 1-2v hotter than the other signals, so I connected it to a point closer to
the main IC and that fixed it :)
> > > > > >
> > > > > > I've disconnected the PPB entirely for further testing today.
> > > > > > The SK only semi-shuts down. The drums can still be heard, but no
keyboard can be heard. This is aslo true without the PPB connected.
> > > > > > I'm not overly sure if this particular SK was faulty before I opened
her up.
> > > > > > I had the PPB wired to the 7.5 of the amp IC... perhaps this would
this cause more hum...
> > > > > >
> > > > > > I contemplated stacking trimpots for a crude 4-gang. I'm still
tempted. With the 5534s, the 2 dual gangs are a lot more usable than the 741s.
I've seen some hex-gang pots on ebay for cheap from China. They're triple-deck,
apparently and look like 3 dual-gang pots piggybacking. They're also cheap at £3
a pot.
> > > > > > Cogs n' gears had crossed my mind, but I'm not sure I have the
skills or tools for the job. It would be beautiful though.
> > > > > >
> > > > > > Thanks for all your help and advice Graham. I'll post my results
soon.
> > > > > > Cheers!
> > > > > > Luke
> > > > > >
> > > > > > --- In CasioSK@yahoogroups.com, "gmeredith1" <gmeredith1@> wrote:
> > > > > > >
> > > > > > > Hi Luke,
> > > > > > >
> > > > > > > Graham here, the designer of the Phat philter Bank. Sorry I missed
your posts, gosh, I go away for a few days and this place gets exciting :D
> > > > > > >
> > > > > > > Glad you got the PPB working, I apologise for making it so cramped
a board layout - I did this so I could mount the full quad board internally
without having to ditch the speaker. One day I'll do a larger, more
mistake-proof layout.
> > > > > > >
> > > > > > > Regarding the squeal - I found that the 741's did exactly that,
too - they are sensitive to the resonant point on the res pot much more than the
5534's. The 5534's are much cleaner sounding as well, so thy're better all
round. They are also more sensitive and have higher gain - and so they'll pick
up hum more than the 741.
> > > > > > >
> > > > > > > Mine does hum but only ever so slightly, and you only notice it
when you turn up the volume past half-way. Mine is mounted in an SK-8
internally. Are you running the SK on batteries or an AC plug pack? The AC plug
pack is possibly making the PPB hum, if you are. Try it on batteries and see if
it still does it.
> > > > > > >
> > > > > > > Is yours internally mounted or separate? Moving mine around inside
to various places created more/less hum. Make sure all your input/output wires
are shielded.
> > > > > > >
> > > > > > > Are you running the outputs of the PPB directly into an amp, or
re-routed back into the amp in the SK? Mine is re-routed to the SK amp.
> > > > > > >
> > > > > > > Try using it outside of the sk, if it isn't already, and see if it
changes the hum issue. At the worst case scenario, unhook it completely from the
sk and test it as a standalone filter, powered by it's own battery and test each
channel input for noise. Also, try mounting it inside a metal enclosure to see
if this shields it from hum.
> > > > > > >
> > > > > > > Regarding the 4th channel being louder than the others - I'm not
sure about it, but one of the SK lines might be a bit louder than the others.
Increase the PPB input resistor to that channel to balance it out with the
others is my suggestion.
> > > > > > >
> > > > > > > Regarding the sk shutting down, are you powering the PPB directly
off the sk, or from its own separate battery? It sounds like you've connected it
to the Sk internally at a certain place and it's draining the +5V processor
power rail and making it think that the batteries are flat. Is this correct? The
PPB best runs off the 7.5V audio power rail inside the SK, which is separate
from the proccesor power rail.
> > > > > > >
> > > > > > > Hope that helps, if nothing helps it, disconnect the PPB from the
SK completely and check it, and then reconnect it in stages, checking each
channel and the hum, and the power issue.
> > > > > > >
> > > > > > > Cheers, Graham
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > --- In CasioSK@yahoogroups.com, "luke" <icanfeelmyselfrotting@>
wrote:
> > > > > > > >
> > > > > > > > The keys cut out after approx. 400 strokes. Which is rubbish.
> > > > > > > > Any advice on this one?
> > > > > > > >
> > > > > > > > On the PPB, I replaced the 741s with 5534s and it has cut the
squealing completely, I am now experiencing a great deal of hum instead, which
is as annoying as the squeal but not as deafening.
> > > > > > > > I imagine it's a loose ground somewhere or some additional caps
are needed or something. The key issue is more vexing.
> > > > > > > >
> > > > > > > > Sorry for the double post btw.
> > > > > > > > Luke
> > > > > > > >
> > > > > > > >
> > > > > > > > --- In CasioSK@yahoogroups.com, "luke" <icanfeelmyselfrotting@>
wrote:
> > > > > > > > >
> > > > > > > > > There's an APO mod on Electri-Fire's site which works a treat.
I've had the demo going for about 20 minutes and the crazy is setting in now...
> > > > > > > > >
> > > > > > > > > I don't think my issues are APO related.
> > > > > > > > > What seems to be happening is the keyboard becomes
unresponsive after about 2-3 minutes of playing. If I up the volume, I can hear
some matrix noise, but no key sounds. The drums are still audible and hitting
the demo button brings the keys back to life. It's strange and annoying.
> > > > > > > > >
> > > > > > > > > You should try the PPB. It's really nice. Gives the SK1 a
whole new dimension. I think the layout could be made less cramped, but for
space saving GMeredith's layout is as packed as could be.
> > > > > > > > >
> > > > > > > > > I'll be putting an LTC1799 in too for pitchability.
> > > > > > > > >
> > > > > > > > > I'll chuck a vid up when she's finished.
> > > > > > > > > Thanks again Tanner
> > > > > > > > >
> > > > > > > > >
> > > > > > > > > --- In CasioSK@yahoogroups.com, "noystois" <noystoise@> wrote:
> > > > > > > > > >
> > > > > > > > > > i dont know, ive never built it. it only turns off 10
minutes after you last touched the sk1 right? not while youre still playing? ive
heard of people trying to modify the sleep circuit on the sk1 but with no
success. seems like all you would need to do is find a redundant i/o that resets
the sleep circuit and hook it up to an lfo or something. i've done this with
other toy keyboards but never an sk1. it might be kind of hard to find
considering you would have to wait 10 minutes to see if it even works. might be
worth it to try and overclock the sk1 so that the sleep circuit only takes like
1 minute or something. just some ideas. glad to hear you got the filter working
though.
> > > > > > > > > >
> > > > > > > > > > --- In CasioSK@yahoogroups.com, "luke"
<icanfeelmyselfrotting@> wrote:
> > > > > > > > > > >
> > > > > > > > > > > Thanks for that Tanner.
> > > > > > > > > > > I actually found the source of the problem... I'd placed
all of the res pot wires after a trace cut instead of before it. A rookie
mistake indeed.
> > > > > > > > > > > SO now I've relocated the wires and it works, but it's
still not great as the 4th module's signal is much hotter than the others.
> > > > > > > > > > >
> > > > > > > > > > > I just wish I had quad gang pots. I'm using 2 pairs of
dual gang and it's not ideal.
> > > > > > > > > > >
> > > > > > > > > > > Other than a few minor issues, the PPB is brilliant.
> > > > > > > > > > >
> > > > > > > > > > > One major problem I'm having is that the SK stops working
after about 10 minutes. The 'on' LED is still lit but no sound can be made. Does
the PPB affect the auto power off function, or is there a way to disable the
APO?
> > > > > > > > > > >
> > > > > > > > > > > Thanks again for the advice.
> > > > > > > > > > > Luke
> > > > > > > > > > >
> > > > > > > > > > > --- In CasioSK@yahoogroups.com, "noystois" <noystoise@>
wrote:
> > > > > > > > > > > >
> > > > > > > > > > > > i dont think the values of those caps are too critical,
they will just change the tone of the filter. the first thing you could try is
adding a decoupling cap say 100mf from the positve power to the ground. but i
think what the real problem might be is that the signal coming in is too high.
you should try replacing the 470k resistor with a 100k pot with one outer lug
going to the .01mf cap, the other lug going to GND and the wiper going to the
signal. its hard for me to understand the stripboard layout but fortunately i
have the original schematic here. it says to set the cutoff all the way up and
the resonance all the way down and then adjust the volume to the filter so that
the output from the filter is only as loud as the original signal. if you are
still getting too much gain, there may be too much resistance between the -in
and the out but i doubt it, its only 200k. good luck. -tanner
> > > > > > > > > > > >
> > > > > > > > > > > > --- In CasioSK@yahoogroups.com, "luke"
<icanfeelmyselfrotting@> wrote:
> > > > > > > > > > > > >
> > > > > > > > > > > > > I've just finished a phat Philter for my SK-1. It
seems to be working reasonably well. However, it squeals like crazy.
> > > > > > > > > > > > >
> > > > > > > > > > > > > I didn't have any NE5443AN op-amps, so I used 741s
instead. Could this be the root of the problem?
> > > > > > > > > > > > >
> > > > > > > > > > > > > Also, I had no 470pf caps so I used 560pf as an
alternative and have also tried 390pf, which alters the tone of the squeal but
does not remedy it completely.
> > > > > > > > > > > > >
> > > > > > > > > > > > > Any ideas or thoughts would be greatly appreciated.
> > > > > > > > > > > > >
> > > > > > > > > > > > > I'm guessing that changing op-amps would probably be
the biggest help.
> > > > > > > > > > > > >
> > > > > > > > > > > > > Luke
> > > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > >
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
>

Hey Luke, that's great news! Glad you liked it. It really turns the SK into a
synthesizer, doesn't it!

For the next mod, you really gotta try my "Slo-AD mod" - for a variable attack
and decay on the sounds. Add this effect to the PPB and it really does sound
like a full blown synth. The preset sounds become completely different
instruments. And it's really simple and easy to do - much much simpler than the
PPB. The plans are in the FILES section here.

Cheers, graham



--- In CasioSK@yahoogroups.com, "luke" <icanfeelmyselfrotting@...> wrote:
>
> Hey Graham.
> It's finished!!!
> I've not got any fresh batteries at the mo to test the PPB. It works well
enough with an adaptor. The hum is only overpowering when the cut-off pots are
fully juiced & when the CV input is in use.
> I'll get a recording done at some point over this weekend.
>
> I hooked the audio out into the internal amp with success. There is a bit of a
pop when it's swithched on/off, but it's not that bad.
>
> Again, thanks for the help.
> It's a beautiful mod that I need to add to everything now!!!!
>
> Luke
>
> --- In CasioSK@yahoogroups.com, "gmeredith1" <gmeredith1@> wrote:
> >
> > Haha, well, I always think it's better to feel like a dumbass and have a
working keyboard than the other way around!
> >
> > Regarding the insert point, yes, it is just before the volume slider and
amplifier circuit. On the SK-8, there is a wire link that you can cut and
connect the PPB output to the volume control and amp side of the link. I'm
almost certain that there will be a similar link in the SK-1.
> >
> > I also put in a PPB bypass switch that used the other side of the link (the
normal SK output side) and used it to toggle between it and the PPB out. Very
useful. In the PPB guide it shows this at the very end of the guide.
> >
> > I've been thinking about your hum problem. After trying it with batteries
and if you still get it, I wonder if it is a ground loop with the PPB, SK-1 and
your amp? Try disconnecting the ground wire to the amp input from the PPB out.
When you do install the PPB into the SK-1 circuit as mentioned above, you don't
need to use a ground wire - only the PPB signal out - as the ground is already
connected through the hooking up of the PPB to the power rails of the SK-1.
> >
> > Maybe, after all else fails, that may work if you were hooking the PPB
directly up to an amp. OR, I suspect that the impedance of the output is all
wrong for certain amp inputs. Is the amp a line input, or a guitar input, or
mic? Line is best I think. Do you have to have the amp volume way down or way up
to get a good level?
> >
> > I'm pretty sure that when you hook it up internally to the internal SK amp
it will be better, even with a power pack connected.
> >
> > Also, just keep in mind that you may have to balance the output volume of
the PPB before the insert point, so that when you bypass it or switch it in, the
volume level is matched ok. To do this, you may have to explore along the insert
point circuit track at various places before or after resistors or caps to get
it right. Or maybe add a resistor to the PPB output if it's too hot, so that it
balances with the bypassed level. On the PPB guide for the SK8 I have chosen the
spot that does this, so I think the SK-1 will also have an optimal spot.
> >
> > If you attach the PPB output wire to a multimeter probe (without the
multimeter), you can have the keyboard playing and use the probed-output to tap
along the SK amp line for this optimum spot. It works a treat for exploring
audio circuits and saves doing temporary soldering.
> >
> > Cheers, Graham
> >
> >
> >
> > --- In CasioSK@yahoogroups.com, "luke" <icanfeelmyselfrotting@> wrote:
> > >
> > > Hey Graham.
> > > Thanks for all the help thus far.
> > > the item number for the hex gang is; 290366887977
> > > Hongkongsuperseller is the traders name.
> > > They're very cheap.
> > >
> > > I'm just in the process of refitting the ppb. I cracked the first
replacement speaker panel so had to make a replacement replacement panel. Such
are the perils of perspex drilling.
> > >
> > > I reversed the APO mod and counted my keystrokes again and it still cut
off after roughly 400 strokes. I had a rhythm playing too and noticed the notes
interrupted the drums. Then I set the sk to 'play' instead of 'record' and
everything is now fine and I feel a bit of a chump :)
> > >
> > > The APO mod for the sk1 seems to leave all other functions intact, but I
don't think it allows the sk to turn off fully manually. I may return this back
to factory as it's probably surplus to my needs.
> > >
> > > To have the PPB going through the internal speaker, does it pass through
the volume slider to the power amp (LA4138)and then to the speaker?
> > >
> > > Thanks again.
> > > Luke
> > >
> > > --- In CasioSK@yahoogroups.com, "gmeredith1" <gmeredith1@> wrote:
> > > >
> > > > Hi Luke,
> > > >
> > > > I'm glad you resolved the hot 4th line, that's great! Perhaps when you
get time you could show the connect points for the SK1 in a photo or something
for those with an SK1.
> > > >
> > > > Regarding powering it, running it off the 7.5V amp line like you had is
the best place to run it for a number of reasons - the main one is that this
voltage line completely powers down when you switch the SK1 off, whereas the 5V
line is always on, even with the power turned off - to retain the processors
settings. On the SK8 it remains powered to also retain the 4 sample memories
when switched off. Hooking the PPB up to the 5V rail will cause the PPB to not
switch off and so drain your batteries whilst switched off.
> > > >
> > > > If you were running it off the power pack it might make the PPB hum a
little if the power pack is a bit rough in its AC smoothing. That's just a guess
- you could try running the SK-1 off batteries to see if this helps. If it
doesn't, try the pot wire shielding - it can only help. The other thing you
could do is try wrapping the whole PPB in foil, with a connection from the foil
to a ground point on the PPB board (Make sure you wrap the board in plastic wrap
first to insulate it from the foil). It's worth a try. Maybe you could email me
a mp3 of the hum whilst, say, playing a rhythm so I can see how much there is.
> > > >
> > > > The other hum source could be the SK1 circuit board itself - namely the
processor - being a computer, it emits electromagnetic radiation that can
interfere with unshielded audio circuits. Mine hummed more or less in certain
parts of the casing, even when running everything off batteries. Not much, and
only when turned up a lot, but you could hear that it was more than the SK1 by
itself. I seem to recall testing the PPB externally before fitting it, running
it off batteries and also the sk off batteries and hearing no hum - I only
noticed the hum when I finally mounted it in the casing and recalled not hearing
it before.
> > > >
> > > > The SK1 shutdown problem - I suspect it's related to the shutdown mod.
Try reversing the mod and put the SK back to stock condition and try it first.
> > > >
> > > > I've never been totally convinced that this mod works on the SK-1. On
the SK-8, it is impossible to implement, because the SK-8 processor itself will
shut down after 7 mins even if you do the mod to it - I tried and tried and
bought the service manual and tried but to no avail. You can get the analog
section to stay awake, and everything LOOKS like its still awake, but the
proceesor goes to sleep and the keyboard becomes unresponsive even though all
the lights are on and you can hear hiss from the speaker. On the SK-8, this is
because the shutdown timer is built-in to the processor chip itself - it's not
an external device disabled by cutting a trace. And somehow, I think that the
SK-1 is the same, although i've heard of elusive reports saying that it does
work. But how much working? ALL functions, or only some?
> > > >
> > > > Hex-gang pots?? Have you got a link to the supplier? That sounds
interesting. The DIY-trimpot setup is woth doing but is a royal pain in the
arse. I stuffed up a couple of sets of trimpots before I got them working. I
DID, however, get an email from someone who was going to use a DIGITAL 4-gang
pot setup. This to me sounds like the best way of all - I'll look into it
sometime. Going digital means you can have as many "gangs" as you like, and
control them all simultaneously off a SINGLE analog pot - and all using a small
chip! I'll post a topic on the Circuitbenders.co.uk forum asking about them - I
think it was someone there who mentioned it.
> > > >
> > > > Keep it happening - let me know how you get on! The PPB is definitely
worth it!
> > > >
> > > > Cheers, Graham
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > --- In CasioSK@yahoogroups.com, "luke" <icanfeelmyselfrotting@> wrote:
> > > > >
> > > > > Hi Graham.
> > > > > Thanks for your numerous replies :)
> > > > > The PPB is great and I'm glad of it's size. If it were much bigger, it
just wouldn't fit into the sk1.
> > > > >
> > > > > I'm running the sk and PPB from an adaptor. It's set to 6volts but
puts out close to 8v. I've not tried with batteries as of yet but I'll give it a
whirl.
> > > > > I'm hoping to internally mount the PPB in the speaker cavity as it is
the most spacious and isolated area in the SK1.
> > > > >
> > > > > I need to replace some wires with shielded cable and tidy up the
under-board jumpers. Will shielding the cutoff pot wires be necessary?
> > > > >
> > > > > The output from the PPB is just hooked up to a jack socket and fed
into my mixer. I'd prefer to have it internally mixed but I'm unsure how to
achieve this.
> > > > >
> > > > > The 4th channel issue was solved. I had hooked it up to the point
labelled in the Files section. I measured the output with my multimeter and it
was 1-2v hotter than the other signals, so I connected it to a point closer to
the main IC and that fixed it :)
> > > > >
> > > > > I've disconnected the PPB entirely for further testing today.
> > > > > The SK only semi-shuts down. The drums can still be heard, but no
keyboard can be heard. This is aslo true without the PPB connected.
> > > > > I'm not overly sure if this particular SK was faulty before I opened
her up.
> > > > > I had the PPB wired to the 7.5 of the amp IC... perhaps this would
this cause more hum...
> > > > >
> > > > > I contemplated stacking trimpots for a crude 4-gang. I'm still
tempted. With the 5534s, the 2 dual gangs are a lot more usable than the 741s.
I've seen some hex-gang pots on ebay for cheap from China. They're triple-deck,
apparently and look like 3 dual-gang pots piggybacking. They're also cheap at £3
a pot.
> > > > > Cogs n' gears had crossed my mind, but I'm not sure I have the skills
or tools for the job. It would be beautiful though.
> > > > >
> > > > > Thanks for all your help and advice Graham. I'll post my results soon.
> > > > > Cheers!
> > > > > Luke
> > > > >
> > > > > --- In CasioSK@yahoogroups.com, "gmeredith1" <gmeredith1@> wrote:
> > > > > >
> > > > > > Hi Luke,
> > > > > >
> > > > > > Graham here, the designer of the Phat philter Bank. Sorry I missed
your posts, gosh, I go away for a few days and this place gets exciting :D
> > > > > >
> > > > > > Glad you got the PPB working, I apologise for making it so cramped a
board layout - I did this so I could mount the full quad board internally
without having to ditch the speaker. One day I'll do a larger, more
mistake-proof layout.
> > > > > >
> > > > > > Regarding the squeal - I found that the 741's did exactly that, too
- they are sensitive to the resonant point on the res pot much more than the
5534's. The 5534's are much cleaner sounding as well, so thy're better all
round. They are also more sensitive and have higher gain - and so they'll pick
up hum more than the 741.
> > > > > >
> > > > > > Mine does hum but only ever so slightly, and you only notice it when
you turn up the volume past half-way. Mine is mounted in an SK-8 internally. Are
you running the SK on batteries or an AC plug pack? The AC plug pack is possibly
making the PPB hum, if you are. Try it on batteries and see if it still does it.
> > > > > >
> > > > > > Is yours internally mounted or separate? Moving mine around inside
to various places created more/less hum. Make sure all your input/output wires
are shielded.
> > > > > >
> > > > > > Are you running the outputs of the PPB directly into an amp, or
re-routed back into the amp in the SK? Mine is re-routed to the SK amp.
> > > > > >
> > > > > > Try using it outside of the sk, if it isn't already, and see if it
changes the hum issue. At the worst case scenario, unhook it completely from the
sk and test it as a standalone filter, powered by it's own battery and test each
channel input for noise. Also, try mounting it inside a metal enclosure to see
if this shields it from hum.
> > > > > >
> > > > > > Regarding the 4th channel being louder than the others - I'm not
sure about it, but one of the SK lines might be a bit louder than the others.
Increase the PPB input resistor to that channel to balance it out with the
others is my suggestion.
> > > > > >
> > > > > > Regarding the sk shutting down, are you powering the PPB directly
off the sk, or from its own separate battery? It sounds like you've connected it
to the Sk internally at a certain place and it's draining the +5V processor
power rail and making it think that the batteries are flat. Is this correct? The
PPB best runs off the 7.5V audio power rail inside the SK, which is separate
from the proccesor power rail.
> > > > > >
> > > > > > Hope that helps, if nothing helps it, disconnect the PPB from the SK
completely and check it, and then reconnect it in stages, checking each channel
and the hum, and the power issue.
> > > > > >
> > > > > > Cheers, Graham
> > > > > >
> > > > > >
> > > > > >
> > > > > > --- In CasioSK@yahoogroups.com, "luke" <icanfeelmyselfrotting@>
wrote:
> > > > > > >
> > > > > > > The keys cut out after approx. 400 strokes. Which is rubbish.
> > > > > > > Any advice on this one?
> > > > > > >
> > > > > > > On the PPB, I replaced the 741s with 5534s and it has cut the
squealing completely, I am now experiencing a great deal of hum instead, which
is as annoying as the squeal but not as deafening.
> > > > > > > I imagine it's a loose ground somewhere or some additional caps
are needed or something. The key issue is more vexing.
> > > > > > >
> > > > > > > Sorry for the double post btw.
> > > > > > > Luke
> > > > > > >
> > > > > > >
> > > > > > > --- In CasioSK@yahoogroups.com, "luke" <icanfeelmyselfrotting@>
wrote:
> > > > > > > >
> > > > > > > > There's an APO mod on Electri-Fire's site which works a treat.
I've had the demo going for about 20 minutes and the crazy is setting in now...
> > > > > > > >
> > > > > > > > I don't think my issues are APO related.
> > > > > > > > What seems to be happening is the keyboard becomes unresponsive
after about 2-3 minutes of playing. If I up the volume, I can hear some matrix
noise, but no key sounds. The drums are still audible and hitting the demo
button brings the keys back to life. It's strange and annoying.
> > > > > > > >
> > > > > > > > You should try the PPB. It's really nice. Gives the SK1 a whole
new dimension. I think the layout could be made less cramped, but for space
saving GMeredith's layout is as packed as could be.
> > > > > > > >
> > > > > > > > I'll be putting an LTC1799 in too for pitchability.
> > > > > > > >
> > > > > > > > I'll chuck a vid up when she's finished.
> > > > > > > > Thanks again Tanner
> > > > > > > >
> > > > > > > >
> > > > > > > > --- In CasioSK@yahoogroups.com, "noystois" <noystoise@> wrote:
> > > > > > > > >
> > > > > > > > > i dont know, ive never built it. it only turns off 10 minutes
after you last touched the sk1 right? not while youre still playing? ive heard
of people trying to modify the sleep circuit on the sk1 but with no success.
seems like all you would need to do is find a redundant i/o that resets the
sleep circuit and hook it up to an lfo or something. i've done this with other
toy keyboards but never an sk1. it might be kind of hard to find considering you
would have to wait 10 minutes to see if it even works. might be worth it to try
and overclock the sk1 so that the sleep circuit only takes like 1 minute or
something. just some ideas. glad to hear you got the filter working though.
> > > > > > > > >
> > > > > > > > > --- In CasioSK@yahoogroups.com, "luke"
<icanfeelmyselfrotting@> wrote:
> > > > > > > > > >
> > > > > > > > > > Thanks for that Tanner.
> > > > > > > > > > I actually found the source of the problem... I'd placed all
of the res pot wires after a trace cut instead of before it. A rookie mistake
indeed.
> > > > > > > > > > SO now I've relocated the wires and it works, but it's still
not great as the 4th module's signal is much hotter than the others.
> > > > > > > > > >
> > > > > > > > > > I just wish I had quad gang pots. I'm using 2 pairs of dual
gang and it's not ideal.
> > > > > > > > > >
> > > > > > > > > > Other than a few minor issues, the PPB is brilliant.
> > > > > > > > > >
> > > > > > > > > > One major problem I'm having is that the SK stops working
after about 10 minutes. The 'on' LED is still lit but no sound can be made. Does
the PPB affect the auto power off function, or is there a way to disable the
APO?
> > > > > > > > > >
> > > > > > > > > > Thanks again for the advice.
> > > > > > > > > > Luke
> > > > > > > > > >
> > > > > > > > > > --- In CasioSK@yahoogroups.com, "noystois" <noystoise@>
wrote:
> > > > > > > > > > >
> > > > > > > > > > > i dont think the values of those caps are too critical,
they will just change the tone of the filter. the first thing you could try is
adding a decoupling cap say 100mf from the positve power to the ground. but i
think what the real problem might be is that the signal coming in is too high.
you should try replacing the 470k resistor with a 100k pot with one outer lug
going to the .01mf cap, the other lug going to GND and the wiper going to the
signal. its hard for me to understand the stripboard layout but fortunately i
have the original schematic here. it says to set the cutoff all the way up and
the resonance all the way down and then adjust the volume to the filter so that
the output from the filter is only as loud as the original signal. if you are
still getting too much gain, there may be too much resistance between the -in
and the out but i doubt it, its only 200k. good luck. -tanner
> > > > > > > > > > >
> > > > > > > > > > > --- In CasioSK@yahoogroups.com, "luke"
<icanfeelmyselfrotting@> wrote:
> > > > > > > > > > > >
> > > > > > > > > > > > I've just finished a phat Philter for my SK-1. It seems
to be working reasonably well. However, it squeals like crazy.
> > > > > > > > > > > >
> > > > > > > > > > > > I didn't have any NE5443AN op-amps, so I used 741s
instead. Could this be the root of the problem?
> > > > > > > > > > > >
> > > > > > > > > > > > Also, I had no 470pf caps so I used 560pf as an
alternative and have also tried 390pf, which alters the tone of the squeal but
does not remedy it completely.
> > > > > > > > > > > >
> > > > > > > > > > > > Any ideas or thoughts would be greatly appreciated.
> > > > > > > > > > > >
> > > > > > > > > > > > I'm guessing that changing op-amps would probably be the
biggest help.
> > > > > > > > > > > >
> > > > > > > > > > > > Luke
> > > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > >
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
>

Hey Graham.
It's finished!!!
I've not got any fresh batteries at the mo to test the PPB. It works well enough
with an adaptor. The hum is only overpowering when the cut-off pots are fully
juiced & when the CV input is in use.
I'll get a recording done at some point over this weekend.

I hooked the audio out into the internal amp with success. There is a bit of a
pop when it's swithched on/off, but it's not that bad.

Again, thanks for the help.
It's a beautiful mod that I need to add to everything now!!!!

Luke

--- In CasioSK@yahoogroups.com, "gmeredith1" <gmeredith1@...> wrote:
>
> Haha, well, I always think it's better to feel like a dumbass and have a
working keyboard than the other way around!
>
> Regarding the insert point, yes, it is just before the volume slider and
amplifier circuit. On the SK-8, there is a wire link that you can cut and
connect the PPB output to the volume control and amp side of the link. I'm
almost certain that there will be a similar link in the SK-1.
>
> I also put in a PPB bypass switch that used the other side of the link (the
normal SK output side) and used it to toggle between it and the PPB out. Very
useful. In the PPB guide it shows this at the very end of the guide.
>
> I've been thinking about your hum problem. After trying it with batteries and
if you still get it, I wonder if it is a ground loop with the PPB, SK-1 and your
amp? Try disconnecting the ground wire to the amp input from the PPB out. When
you do install the PPB into the SK-1 circuit as mentioned above, you don't need
to use a ground wire - only the PPB signal out - as the ground is already
connected through the hooking up of the PPB to the power rails of the SK-1.
>
> Maybe, after all else fails, that may work if you were hooking the PPB
directly up to an amp. OR, I suspect that the impedance of the output is all
wrong for certain amp inputs. Is the amp a line input, or a guitar input, or
mic? Line is best I think. Do you have to have the amp volume way down or way up
to get a good level?
>
> I'm pretty sure that when you hook it up internally to the internal SK amp it
will be better, even with a power pack connected.
>
> Also, just keep in mind that you may have to balance the output volume of the
PPB before the insert point, so that when you bypass it or switch it in, the
volume level is matched ok. To do this, you may have to explore along the insert
point circuit track at various places before or after resistors or caps to get
it right. Or maybe add a resistor to the PPB output if it's too hot, so that it
balances with the bypassed level. On the PPB guide for the SK8 I have chosen the
spot that does this, so I think the SK-1 will also have an optimal spot.
>
> If you attach the PPB output wire to a multimeter probe (without the
multimeter), you can have the keyboard playing and use the probed-output to tap
along the SK amp line for this optimum spot. It works a treat for exploring
audio circuits and saves doing temporary soldering.
>
> Cheers, Graham
>
>
>
> --- In CasioSK@yahoogroups.com, "luke" <icanfeelmyselfrotting@> wrote:
> >
> > Hey Graham.
> > Thanks for all the help thus far.
> > the item number for the hex gang is; 290366887977
> > Hongkongsuperseller is the traders name.
> > They're very cheap.
> >
> > I'm just in the process of refitting the ppb. I cracked the first
replacement speaker panel so had to make a replacement replacement panel. Such
are the perils of perspex drilling.
> >
> > I reversed the APO mod and counted my keystrokes again and it still cut off
after roughly 400 strokes. I had a rhythm playing too and noticed the notes
interrupted the drums. Then I set the sk to 'play' instead of 'record' and
everything is now fine and I feel a bit of a chump :)
> >
> > The APO mod for the sk1 seems to leave all other functions intact, but I
don't think it allows the sk to turn off fully manually. I may return this back
to factory as it's probably surplus to my needs.
> >
> > To have the PPB going through the internal speaker, does it pass through the
volume slider to the power amp (LA4138)and then to the speaker?
> >
> > Thanks again.
> > Luke
> >
> > --- In CasioSK@yahoogroups.com, "gmeredith1" <gmeredith1@> wrote:
> > >
> > > Hi Luke,
> > >
> > > I'm glad you resolved the hot 4th line, that's great! Perhaps when you get
time you could show the connect points for the SK1 in a photo or something for
those with an SK1.
> > >
> > > Regarding powering it, running it off the 7.5V amp line like you had is
the best place to run it for a number of reasons - the main one is that this
voltage line completely powers down when you switch the SK1 off, whereas the 5V
line is always on, even with the power turned off - to retain the processors
settings. On the SK8 it remains powered to also retain the 4 sample memories
when switched off. Hooking the PPB up to the 5V rail will cause the PPB to not
switch off and so drain your batteries whilst switched off.
> > >
> > > If you were running it off the power pack it might make the PPB hum a
little if the power pack is a bit rough in its AC smoothing. That's just a guess
- you could try running the SK-1 off batteries to see if this helps. If it
doesn't, try the pot wire shielding - it can only help. The other thing you
could do is try wrapping the whole PPB in foil, with a connection from the foil
to a ground point on the PPB board (Make sure you wrap the board in plastic wrap
first to insulate it from the foil). It's worth a try. Maybe you could email me
a mp3 of the hum whilst, say, playing a rhythm so I can see how much there is.
> > >
> > > The other hum source could be the SK1 circuit board itself - namely the
processor - being a computer, it emits electromagnetic radiation that can
interfere with unshielded audio circuits. Mine hummed more or less in certain
parts of the casing, even when running everything off batteries. Not much, and
only when turned up a lot, but you could hear that it was more than the SK1 by
itself. I seem to recall testing the PPB externally before fitting it, running
it off batteries and also the sk off batteries and hearing no hum - I only
noticed the hum when I finally mounted it in the casing and recalled not hearing
it before.
> > >
> > > The SK1 shutdown problem - I suspect it's related to the shutdown mod. Try
reversing the mod and put the SK back to stock condition and try it first.
> > >
> > > I've never been totally convinced that this mod works on the SK-1. On the
SK-8, it is impossible to implement, because the SK-8 processor itself will shut
down after 7 mins even if you do the mod to it - I tried and tried and bought
the service manual and tried but to no avail. You can get the analog section to
stay awake, and everything LOOKS like its still awake, but the proceesor goes to
sleep and the keyboard becomes unresponsive even though all the lights are on
and you can hear hiss from the speaker. On the SK-8, this is because the
shutdown timer is built-in to the processor chip itself - it's not an external
device disabled by cutting a trace. And somehow, I think that the SK-1 is the
same, although i've heard of elusive reports saying that it does work. But how
much working? ALL functions, or only some?
> > >
> > > Hex-gang pots?? Have you got a link to the supplier? That sounds
interesting. The DIY-trimpot setup is woth doing but is a royal pain in the
arse. I stuffed up a couple of sets of trimpots before I got them working. I
DID, however, get an email from someone who was going to use a DIGITAL 4-gang
pot setup. This to me sounds like the best way of all - I'll look into it
sometime. Going digital means you can have as many "gangs" as you like, and
control them all simultaneously off a SINGLE analog pot - and all using a small
chip! I'll post a topic on the Circuitbenders.co.uk forum asking about them - I
think it was someone there who mentioned it.
> > >
> > > Keep it happening - let me know how you get on! The PPB is definitely
worth it!
> > >
> > > Cheers, Graham
> > >
> > >
> > >
> > >
> > >
> > > --- In CasioSK@yahoogroups.com, "luke" <icanfeelmyselfrotting@> wrote:
> > > >
> > > > Hi Graham.
> > > > Thanks for your numerous replies :)
> > > > The PPB is great and I'm glad of it's size. If it were much bigger, it
just wouldn't fit into the sk1.
> > > >
> > > > I'm running the sk and PPB from an adaptor. It's set to 6volts but puts
out close to 8v. I've not tried with batteries as of yet but I'll give it a
whirl.
> > > > I'm hoping to internally mount the PPB in the speaker cavity as it is
the most spacious and isolated area in the SK1.
> > > >
> > > > I need to replace some wires with shielded cable and tidy up the
under-board jumpers. Will shielding the cutoff pot wires be necessary?
> > > >
> > > > The output from the PPB is just hooked up to a jack socket and fed into
my mixer. I'd prefer to have it internally mixed but I'm unsure how to achieve
this.
> > > >
> > > > The 4th channel issue was solved. I had hooked it up to the point
labelled in the Files section. I measured the output with my multimeter and it
was 1-2v hotter than the other signals, so I connected it to a point closer to
the main IC and that fixed it :)
> > > >
> > > > I've disconnected the PPB entirely for further testing today.
> > > > The SK only semi-shuts down. The drums can still be heard, but no
keyboard can be heard. This is aslo true without the PPB connected.
> > > > I'm not overly sure if this particular SK was faulty before I opened her
up.
> > > > I had the PPB wired to the 7.5 of the amp IC... perhaps this would this
cause more hum...
> > > >
> > > > I contemplated stacking trimpots for a crude 4-gang. I'm still tempted.
With the 5534s, the 2 dual gangs are a lot more usable than the 741s. I've seen
some hex-gang pots on ebay for cheap from China. They're triple-deck, apparently
and look like 3 dual-gang pots piggybacking. They're also cheap at £3 a pot.
> > > > Cogs n' gears had crossed my mind, but I'm not sure I have the skills or
tools for the job. It would be beautiful though.
> > > >
> > > > Thanks for all your help and advice Graham. I'll post my results soon.
> > > > Cheers!
> > > > Luke
> > > >
> > > > --- In CasioSK@yahoogroups.com, "gmeredith1" <gmeredith1@> wrote:
> > > > >
> > > > > Hi Luke,
> > > > >
> > > > > Graham here, the designer of the Phat philter Bank. Sorry I missed
your posts, gosh, I go away for a few days and this place gets exciting :D
> > > > >
> > > > > Glad you got the PPB working, I apologise for making it so cramped a
board layout - I did this so I could mount the full quad board internally
without having to ditch the speaker. One day I'll do a larger, more
mistake-proof layout.
> > > > >
> > > > > Regarding the squeal - I found that the 741's did exactly that, too -
they are sensitive to the resonant point on the res pot much more than the
5534's. The 5534's are much cleaner sounding as well, so thy're better all
round. They are also more sensitive and have higher gain - and so they'll pick
up hum more than the 741.
> > > > >
> > > > > Mine does hum but only ever so slightly, and you only notice it when
you turn up the volume past half-way. Mine is mounted in an SK-8 internally. Are
you running the SK on batteries or an AC plug pack? The AC plug pack is possibly
making the PPB hum, if you are. Try it on batteries and see if it still does it.
> > > > >
> > > > > Is yours internally mounted or separate? Moving mine around inside to
various places created more/less hum. Make sure all your input/output wires are
shielded.
> > > > >
> > > > > Are you running the outputs of the PPB directly into an amp, or
re-routed back into the amp in the SK? Mine is re-routed to the SK amp.
> > > > >
> > > > > Try using it outside of the sk, if it isn't already, and see if it
changes the hum issue. At the worst case scenario, unhook it completely from the
sk and test it as a standalone filter, powered by it's own battery and test each
channel input for noise. Also, try mounting it inside a metal enclosure to see
if this shields it from hum.
> > > > >
> > > > > Regarding the 4th channel being louder than the others - I'm not sure
about it, but one of the SK lines might be a bit louder than the others.
Increase the PPB input resistor to that channel to balance it out with the
others is my suggestion.
> > > > >
> > > > > Regarding the sk shutting down, are you powering the PPB directly off
the sk, or from its own separate battery? It sounds like you've connected it to
the Sk internally at a certain place and it's draining the +5V processor power
rail and making it think that the batteries are flat. Is this correct? The PPB
best runs off the 7.5V audio power rail inside the SK, which is separate from
the proccesor power rail.
> > > > >
> > > > > Hope that helps, if nothing helps it, disconnect the PPB from the SK
completely and check it, and then reconnect it in stages, checking each channel
and the hum, and the power issue.
> > > > >
> > > > > Cheers, Graham
> > > > >
> > > > >
> > > > >
> > > > > --- In CasioSK@yahoogroups.com, "luke" <icanfeelmyselfrotting@> wrote:
> > > > > >
> > > > > > The keys cut out after approx. 400 strokes. Which is rubbish.
> > > > > > Any advice on this one?
> > > > > >
> > > > > > On the PPB, I replaced the 741s with 5534s and it has cut the
squealing completely, I am now experiencing a great deal of hum instead, which
is as annoying as the squeal but not as deafening.
> > > > > > I imagine it's a loose ground somewhere or some additional caps are
needed or something. The key issue is more vexing.
> > > > > >
> > > > > > Sorry for the double post btw.
> > > > > > Luke
> > > > > >
> > > > > >
> > > > > > --- In CasioSK@yahoogroups.com, "luke" <icanfeelmyselfrotting@>
wrote:
> > > > > > >
> > > > > > > There's an APO mod on Electri-Fire's site which works a treat.
I've had the demo going for about 20 minutes and the crazy is setting in now...
> > > > > > >
> > > > > > > I don't think my issues are APO related.
> > > > > > > What seems to be happening is the keyboard becomes unresponsive
after about 2-3 minutes of playing. If I up the volume, I can hear some matrix
noise, but no key sounds. The drums are still audible and hitting the demo
button brings the keys back to life. It's strange and annoying.
> > > > > > >
> > > > > > > You should try the PPB. It's really nice. Gives the SK1 a whole
new dimension. I think the layout could be made less cramped, but for space
saving GMeredith's layout is as packed as could be.
> > > > > > >
> > > > > > > I'll be putting an LTC1799 in too for pitchability.
> > > > > > >
> > > > > > > I'll chuck a vid up when she's finished.
> > > > > > > Thanks again Tanner
> > > > > > >
> > > > > > >
> > > > > > > --- In CasioSK@yahoogroups.com, "noystois" <noystoise@> wrote:
> > > > > > > >
> > > > > > > > i dont know, ive never built it. it only turns off 10 minutes
after you last touched the sk1 right? not while youre still playing? ive heard
of people trying to modify the sleep circuit on the sk1 but with no success.
seems like all you would need to do is find a redundant i/o that resets the
sleep circuit and hook it up to an lfo or something. i've done this with other
toy keyboards but never an sk1. it might be kind of hard to find considering you
would have to wait 10 minutes to see if it even works. might be worth it to try
and overclock the sk1 so that the sleep circuit only takes like 1 minute or
something. just some ideas. glad to hear you got the filter working though.
> > > > > > > >
> > > > > > > > --- In CasioSK@yahoogroups.com, "luke" <icanfeelmyselfrotting@>
wrote:
> > > > > > > > >
> > > > > > > > > Thanks for that Tanner.
> > > > > > > > > I actually found the source of the problem... I'd placed all
of the res pot wires after a trace cut instead of before it. A rookie mistake
indeed.
> > > > > > > > > SO now I've relocated the wires and it works, but it's still
not great as the 4th module's signal is much hotter than the others.
> > > > > > > > >
> > > > > > > > > I just wish I had quad gang pots. I'm using 2 pairs of dual
gang and it's not ideal.
> > > > > > > > >
> > > > > > > > > Other than a few minor issues, the PPB is brilliant.
> > > > > > > > >
> > > > > > > > > One major problem I'm having is that the SK stops working
after about 10 minutes. The 'on' LED is still lit but no sound can be made. Does
the PPB affect the auto power off function, or is there a way to disable the
APO?
> > > > > > > > >
> > > > > > > > > Thanks again for the advice.
> > > > > > > > > Luke
> > > > > > > > >
> > > > > > > > > --- In CasioSK@yahoogroups.com, "noystois" <noystoise@> wrote:
> > > > > > > > > >
> > > > > > > > > > i dont think the values of those caps are too critical, they
will just change the tone of the filter. the first thing you could try is adding
a decoupling cap say 100mf from the positve power to the ground. but i think
what the real problem might be is that the signal coming in is too high. you
should try replacing the 470k resistor with a 100k pot with one outer lug going
to the .01mf cap, the other lug going to GND and the wiper going to the signal.
its hard for me to understand the stripboard layout but fortunately i have the
original schematic here. it says to set the cutoff all the way up and the
resonance all the way down and then adjust the volume to the filter so that the
output from the filter is only as loud as the original signal. if you are still
getting too much gain, there may be too much resistance between the -in and the
out but i doubt it, its only 200k. good luck. -tanner
> > > > > > > > > >
> > > > > > > > > > --- In CasioSK@yahoogroups.com, "luke"
<icanfeelmyselfrotting@> wrote:
> > > > > > > > > > >
> > > > > > > > > > > I've just finished a phat Philter for my SK-1. It seems to
be working reasonably well. However, it squeals like crazy.
> > > > > > > > > > >
> > > > > > > > > > > I didn't have any NE5443AN op-amps, so I used 741s
instead. Could this be the root of the problem?
> > > > > > > > > > >
> > > > > > > > > > > Also, I had no 470pf caps so I used 560pf as an
alternative and have also tried 390pf, which alters the tone of the squeal but
does not remedy it completely.
> > > > > > > > > > >
> > > > > > > > > > > Any ideas or thoughts would be greatly appreciated.
> > > > > > > > > > >
> > > > > > > > > > > I'm guessing that changing op-amps would probably be the
biggest help.
> > > > > > > > > > >
> > > > > > > > > > > Luke
> > > > > > > > > > >
> > > > > > > > > >
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
>

Haha, well, I always think it's better to feel like a dumbass and have a working
keyboard than the other way around!

Regarding the insert point, yes, it is just before the volume slider and
amplifier circuit. On the SK-8, there is a wire link that you can cut and
connect the PPB output to the volume control and amp side of the link. I'm
almost certain that there will be a similar link in the SK-1.

I also put in a PPB bypass switch that used the other side of the link (the
normal SK output side) and used it to toggle between it and the PPB out. Very
useful. In the PPB guide it shows this at the very end of the guide.

I've been thinking about your hum problem. After trying it with batteries and if
you still get it, I wonder if it is a ground loop with the PPB, SK-1 and your
amp? Try disconnecting the ground wire to the amp input from the PPB out. When
you do install the PPB into the SK-1 circuit as mentioned above, you don't need
to use a ground wire - only the PPB signal out - as the ground is already
connected through the hooking up of the PPB to the power rails of the SK-1.

Maybe, after all else fails, that may work if you were hooking the PPB directly
up to an amp. OR, I suspect that the impedance of the output is all wrong for
certain amp inputs. Is the amp a line input, or a guitar input, or mic? Line is
best I think. Do you have to have the amp volume way down or way up to get a
good level?

I'm pretty sure that when you hook it up internally to the internal SK amp it
will be better, even with a power pack connected.

Also, just keep in mind that you may have to balance the output volume of the
PPB before the insert point, so that when you bypass it or switch it in, the
volume level is matched ok. To do this, you may have to explore along the insert
point circuit track at various places before or after resistors or caps to get
it right. Or maybe add a resistor to the PPB output if it's too hot, so that it
balances with the bypassed level. On the PPB guide for the SK8 I have chosen the
spot that does this, so I think the SK-1 will also have an optimal spot.

If you attach the PPB output wire to a multimeter probe (without the
multimeter), you can have the keyboard playing and use the probed-output to tap
along the SK amp line for this optimum spot. It works a treat for exploring
audio circuits and saves doing temporary soldering.

Cheers, Graham



--- In CasioSK@yahoogroups.com, "luke" <icanfeelmyselfrotting@...> wrote:
>
> Hey Graham.
> Thanks for all the help thus far.
> the item number for the hex gang is; 290366887977
> Hongkongsuperseller is the traders name.
> They're very cheap.
>
> I'm just in the process of refitting the ppb. I cracked the first replacement
speaker panel so had to make a replacement replacement panel. Such are the
perils of perspex drilling.
>
> I reversed the APO mod and counted my keystrokes again and it still cut off
after roughly 400 strokes. I had a rhythm playing too and noticed the notes
interrupted the drums. Then I set the sk to 'play' instead of 'record' and
everything is now fine and I feel a bit of a chump :)
>
> The APO mod for the sk1 seems to leave all other functions intact, but I don't
think it allows the sk to turn off fully manually. I may return this back to
factory as it's probably surplus to my needs.
>
> To have the PPB going through the internal speaker, does it pass through the
volume slider to the power amp (LA4138)and then to the speaker?
>
> Thanks again.
> Luke
>
> --- In CasioSK@yahoogroups.com, "gmeredith1" <gmeredith1@> wrote:
> >
> > Hi Luke,
> >
> > I'm glad you resolved the hot 4th line, that's great! Perhaps when you get
time you could show the connect points for the SK1 in a photo or something for
those with an SK1.
> >
> > Regarding powering it, running it off the 7.5V amp line like you had is the
best place to run it for a number of reasons - the main one is that this voltage
line completely powers down when you switch the SK1 off, whereas the 5V line is
always on, even with the power turned off - to retain the processors settings.
On the SK8 it remains powered to also retain the 4 sample memories when switched
off. Hooking the PPB up to the 5V rail will cause the PPB to not switch off and
so drain your batteries whilst switched off.
> >
> > If you were running it off the power pack it might make the PPB hum a little
if the power pack is a bit rough in its AC smoothing. That's just a guess - you
could try running the SK-1 off batteries to see if this helps. If it doesn't,
try the pot wire shielding - it can only help. The other thing you could do is
try wrapping the whole PPB in foil, with a connection from the foil to a ground
point on the PPB board (Make sure you wrap the board in plastic wrap first to
insulate it from the foil). It's worth a try. Maybe you could email me a mp3 of
the hum whilst, say, playing a rhythm so I can see how much there is.
> >
> > The other hum source could be the SK1 circuit board itself - namely the
processor - being a computer, it emits electromagnetic radiation that can
interfere with unshielded audio circuits. Mine hummed more or less in certain
parts of the casing, even when running everything off batteries. Not much, and
only when turned up a lot, but you could hear that it was more than the SK1 by
itself. I seem to recall testing the PPB externally before fitting it, running
it off batteries and also the sk off batteries and hearing no hum - I only
noticed the hum when I finally mounted it in the casing and recalled not hearing
it before.
> >
> > The SK1 shutdown problem - I suspect it's related to the shutdown mod. Try
reversing the mod and put the SK back to stock condition and try it first.
> >
> > I've never been totally convinced that this mod works on the SK-1. On the
SK-8, it is impossible to implement, because the SK-8 processor itself will shut
down after 7 mins even if you do the mod to it - I tried and tried and bought
the service manual and tried but to no avail. You can get the analog section to
stay awake, and everything LOOKS like its still awake, but the proceesor goes to
sleep and the keyboard becomes unresponsive even though all the lights are on
and you can hear hiss from the speaker. On the SK-8, this is because the
shutdown timer is built-in to the processor chip itself - it's not an external
device disabled by cutting a trace. And somehow, I think that the SK-1 is the
same, although i've heard of elusive reports saying that it does work. But how
much working? ALL functions, or only some?
> >
> > Hex-gang pots?? Have you got a link to the supplier? That sounds
interesting. The DIY-trimpot setup is woth doing but is a royal pain in the
arse. I stuffed up a couple of sets of trimpots before I got them working. I
DID, however, get an email from someone who was going to use a DIGITAL 4-gang
pot setup. This to me sounds like the best way of all - I'll look into it
sometime. Going digital means you can have as many "gangs" as you like, and
control them all simultaneously off a SINGLE analog pot - and all using a small
chip! I'll post a topic on the Circuitbenders.co.uk forum asking about them - I
think it was someone there who mentioned it.
> >
> > Keep it happening - let me know how you get on! The PPB is definitely worth
it!
> >
> > Cheers, Graham
> >
> >
> >
> >
> >
> > --- In CasioSK@yahoogroups.com, "luke" <icanfeelmyselfrotting@> wrote:
> > >
> > > Hi Graham.
> > > Thanks for your numerous replies :)
> > > The PPB is great and I'm glad of it's size. If it were much bigger, it
just wouldn't fit into the sk1.
> > >
> > > I'm running the sk and PPB from an adaptor. It's set to 6volts but puts
out close to 8v. I've not tried with batteries as of yet but I'll give it a
whirl.
> > > I'm hoping to internally mount the PPB in the speaker cavity as it is the
most spacious and isolated area in the SK1.
> > >
> > > I need to replace some wires with shielded cable and tidy up the
under-board jumpers. Will shielding the cutoff pot wires be necessary?
> > >
> > > The output from the PPB is just hooked up to a jack socket and fed into my
mixer. I'd prefer to have it internally mixed but I'm unsure how to achieve
this.
> > >
> > > The 4th channel issue was solved. I had hooked it up to the point labelled
in the Files section. I measured the output with my multimeter and it was 1-2v
hotter than the other signals, so I connected it to a point closer to the main
IC and that fixed it :)
> > >
> > > I've disconnected the PPB entirely for further testing today.
> > > The SK only semi-shuts down. The drums can still be heard, but no keyboard
can be heard. This is aslo true without the PPB connected.
> > > I'm not overly sure if this particular SK was faulty before I opened her
up.
> > > I had the PPB wired to the 7.5 of the amp IC... perhaps this would this
cause more hum...
> > >
> > > I contemplated stacking trimpots for a crude 4-gang. I'm still tempted.
With the 5534s, the 2 dual gangs are a lot more usable than the 741s. I've seen
some hex-gang pots on ebay for cheap from China. They're triple-deck, apparently
and look like 3 dual-gang pots piggybacking. They're also cheap at £3 a pot.
> > > Cogs n' gears had crossed my mind, but I'm not sure I have the skills or
tools for the job. It would be beautiful though.
> > >
> > > Thanks for all your help and advice Graham. I'll post my results soon.
> > > Cheers!
> > > Luke
> > >
> > > --- In CasioSK@yahoogroups.com, "gmeredith1" <gmeredith1@> wrote:
> > > >
> > > > Hi Luke,
> > > >
> > > > Graham here, the designer of the Phat philter Bank. Sorry I missed your
posts, gosh, I go away for a few days and this place gets exciting :D
> > > >
> > > > Glad you got the PPB working, I apologise for making it so cramped a
board layout - I did this so I could mount the full quad board internally
without having to ditch the speaker. One day I'll do a larger, more
mistake-proof layout.
> > > >
> > > > Regarding the squeal - I found that the 741's did exactly that, too -
they are sensitive to the resonant point on the res pot much more than the
5534's. The 5534's are much cleaner sounding as well, so thy're better all
round. They are also more sensitive and have higher gain - and so they'll pick
up hum more than the 741.
> > > >
> > > > Mine does hum but only ever so slightly, and you only notice it when you
turn up the volume past half-way. Mine is mounted in an SK-8 internally. Are you
running the SK on batteries or an AC plug pack? The AC plug pack is possibly
making the PPB hum, if you are. Try it on batteries and see if it still does it.
> > > >
> > > > Is yours internally mounted or separate? Moving mine around inside to
various places created more/less hum. Make sure all your input/output wires are
shielded.
> > > >
> > > > Are you running the outputs of the PPB directly into an amp, or
re-routed back into the amp in the SK? Mine is re-routed to the SK amp.
> > > >
> > > > Try using it outside of the sk, if it isn't already, and see if it
changes the hum issue. At the worst case scenario, unhook it completely from the
sk and test it as a standalone filter, powered by it's own battery and test each
channel input for noise. Also, try mounting it inside a metal enclosure to see
if this shields it from hum.
> > > >
> > > > Regarding the 4th channel being louder than the others - I'm not sure
about it, but one of the SK lines might be a bit louder than the others.
Increase the PPB input resistor to that channel to balance it out with the
others is my suggestion.
> > > >
> > > > Regarding the sk shutting down, are you powering the PPB directly off
the sk, or from its own separate battery? It sounds like you've connected it to
the Sk internally at a certain place and it's draining the +5V processor power
rail and making it think that the batteries are flat. Is this correct? The PPB
best runs off the 7.5V audio power rail inside the SK, which is separate from
the proccesor power rail.
> > > >
> > > > Hope that helps, if nothing helps it, disconnect the PPB from the SK
completely and check it, and then reconnect it in stages, checking each channel
and the hum, and the power issue.
> > > >
> > > > Cheers, Graham
> > > >
> > > >
> > > >
> > > > --- In CasioSK@yahoogroups.com, "luke" <icanfeelmyselfrotting@> wrote:
> > > > >
> > > > > The keys cut out after approx. 400 strokes. Which is rubbish.
> > > > > Any advice on this one?
> > > > >
> > > > > On the PPB, I replaced the 741s with 5534s and it has cut the
squealing completely, I am now experiencing a great deal of hum instead, which
is as annoying as the squeal but not as deafening.
> > > > > I imagine it's a loose ground somewhere or some additional caps are
needed or something. The key issue is more vexing.
> > > > >
> > > > > Sorry for the double post btw.
> > > > > Luke
> > > > >
> > > > >
> > > > > --- In CasioSK@yahoogroups.com, "luke" <icanfeelmyselfrotting@> wrote:
> > > > > >
> > > > > > There's an APO mod on Electri-Fire's site which works a treat. I've
had the demo going for about 20 minutes and the crazy is setting in now...
> > > > > >
> > > > > > I don't think my issues are APO related.
> > > > > > What seems to be happening is the keyboard becomes unresponsive
after about 2-3 minutes of playing. If I up the volume, I can hear some matrix
noise, but no key sounds. The drums are still audible and hitting the demo
button brings the keys back to life. It's strange and annoying.
> > > > > >
> > > > > > You should try the PPB. It's really nice. Gives the SK1 a whole new
dimension. I think the layout could be made less cramped, but for space saving
GMeredith's layout is as packed as could be.
> > > > > >
> > > > > > I'll be putting an LTC1799 in too for pitchability.
> > > > > >
> > > > > > I'll chuck a vid up when she's finished.
> > > > > > Thanks again Tanner
> > > > > >
> > > > > >
> > > > > > --- In CasioSK@yahoogroups.com, "noystois" <noystoise@> wrote:
> > > > > > >
> > > > > > > i dont know, ive never built it. it only turns off 10 minutes
after you last touched the sk1 right? not while youre still playing? ive heard
of people trying to modify the sleep circuit on the sk1 but with no success.
seems like all you would need to do is find a redundant i/o that resets the
sleep circuit and hook it up to an lfo or something. i've done this with other
toy keyboards but never an sk1. it might be kind of hard to find considering you
would have to wait 10 minutes to see if it even works. might be worth it to try
and overclock the sk1 so that the sleep circuit only takes like 1 minute or
something. just some ideas. glad to hear you got the filter working though.
> > > > > > >
> > > > > > > --- In CasioSK@yahoogroups.com, "luke" <icanfeelmyselfrotting@>
wrote:
> > > > > > > >
> > > > > > > > Thanks for that Tanner.
> > > > > > > > I actually found the source of the problem... I'd placed all of
the res pot wires after a trace cut instead of before it. A rookie mistake
indeed.
> > > > > > > > SO now I've relocated the wires and it works, but it's still not
great as the 4th module's signal is much hotter than the others.
> > > > > > > >
> > > > > > > > I just wish I had quad gang pots. I'm using 2 pairs of dual gang
and it's not ideal.
> > > > > > > >
> > > > > > > > Other than a few minor issues, the PPB is brilliant.
> > > > > > > >
> > > > > > > > One major problem I'm having is that the SK stops working after
about 10 minutes. The 'on' LED is still lit but no sound can be made. Does the
PPB affect the auto power off function, or is there a way to disable the APO?
> > > > > > > >
> > > > > > > > Thanks again for the advice.
> > > > > > > > Luke
> > > > > > > >
> > > > > > > > --- In CasioSK@yahoogroups.com, "noystois" <noystoise@> wrote:
> > > > > > > > >
> > > > > > > > > i dont think the values of those caps are too critical, they
will just change the tone of the filter. the first thing you could try is adding
a decoupling cap say 100mf from the positve power to the ground. but i think
what the real problem might be is that the signal coming in is too high. you
should try replacing the 470k resistor with a 100k pot with one outer lug going
to the .01mf cap, the other lug going to GND and the wiper going to the signal.
its hard for me to understand the stripboard layout but fortunately i have the
original schematic here. it says to set the cutoff all the way up and the
resonance all the way down and then adjust the volume to the filter so that the
output from the filter is only as loud as the original signal. if you are still
getting too much gain, there may be too much resistance between the -in and the
out but i doubt it, its only 200k. good luck. -tanner
> > > > > > > > >
> > > > > > > > > --- In CasioSK@yahoogroups.com, "luke"
<icanfeelmyselfrotting@> wrote:
> > > > > > > > > >
> > > > > > > > > > I've just finished a phat Philter for my SK-1. It seems to
be working reasonably well. However, it squeals like crazy.
> > > > > > > > > >
> > > > > > > > > > I didn't have any NE5443AN op-amps, so I used 741s instead.
Could this be the root of the problem?
> > > > > > > > > >
> > > > > > > > > > Also, I had no 470pf caps so I used 560pf as an alternative
and have also tried 390pf, which alters the tone of the squeal but does not
remedy it completely.
> > > > > > > > > >
> > > > > > > > > > Any ideas or thoughts would be greatly appreciated.
> > > > > > > > > >
> > > > > > > > > > I'm guessing that changing op-amps would probably be the
biggest help.
> > > > > > > > > >
> > > > > > > > > > Luke
> > > > > > > > > >
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
>

Hey Graham.
Thanks for all the help thus far.
the item number for the hex gang is; 290366887977
Hongkongsuperseller is the traders name.
They're very cheap.

I'm just in the process of refitting the ppb. I cracked the first replacement
speaker panel so had to make a replacement replacement panel. Such are the
perils of perspex drilling.

I reversed the APO mod and counted my keystrokes again and it still cut off
after roughly 400 strokes. I had a rhythm playing too and noticed the notes
interrupted the drums. Then I set the sk to 'play' instead of 'record' and
everything is now fine and I feel a bit of a chump :)

The APO mod for the sk1 seems to leave all other functions intact, but I don't
think it allows the sk to turn off fully manually. I may return this back to
factory as it's probably surplus to my needs.

To have the PPB going through the internal speaker, does it pass through the
volume slider to the power amp (LA4138)and then to the speaker?

Thanks again.
Luke

--- In CasioSK@yahoogroups.com, "gmeredith1" <gmeredith1@...> wrote:
>
> Hi Luke,
>
> I'm glad you resolved the hot 4th line, that's great! Perhaps when you get
time you could show the connect points for the SK1 in a photo or something for
those with an SK1.
>
> Regarding powering it, running it off the 7.5V amp line like you had is the
best place to run it for a number of reasons - the main one is that this voltage
line completely powers down when you switch the SK1 off, whereas the 5V line is
always on, even with the power turned off - to retain the processors settings.
On the SK8 it remains powered to also retain the 4 sample memories when switched
off. Hooking the PPB up to the 5V rail will cause the PPB to not switch off and
so drain your batteries whilst switched off.
>
> If you were running it off the power pack it might make the PPB hum a little
if the power pack is a bit rough in its AC smoothing. That's just a guess - you
could try running the SK-1 off batteries to see if this helps. If it doesn't,
try the pot wire shielding - it can only help. The other thing you could do is
try wrapping the whole PPB in foil, with a connection from the foil to a ground
point on the PPB board (Make sure you wrap the board in plastic wrap first to
insulate it from the foil). It's worth a try. Maybe you could email me a mp3 of
the hum whilst, say, playing a rhythm so I can see how much there is.
>
> The other hum source could be the SK1 circuit board itself - namely the
processor - being a computer, it emits electromagnetic radiation that can
interfere with unshielded audio circuits. Mine hummed more or less in certain
parts of the casing, even when running everything off batteries. Not much, and
only when turned up a lot, but you could hear that it was more than the SK1 by
itself. I seem to recall testing the PPB externally before fitting it, running
it off batteries and also the sk off batteries and hearing no hum - I only
noticed the hum when I finally mounted it in the casing and recalled not hearing
it before.
>
> The SK1 shutdown problem - I suspect it's related to the shutdown mod. Try
reversing the mod and put the SK back to stock condition and try it first.
>
> I've never been totally convinced that this mod works on the SK-1. On the
SK-8, it is impossible to implement, because the SK-8 processor itself will shut
down after 7 mins even if you do the mod to it - I tried and tried and bought
the service manual and tried but to no avail. You can get the analog section to
stay awake, and everything LOOKS like its still awake, but the proceesor goes to
sleep and the keyboard becomes unresponsive even though all the lights are on
and you can hear hiss from the speaker. On the SK-8, this is because the
shutdown timer is built-in to the processor chip itself - it's not an external
device disabled by cutting a trace. And somehow, I think that the SK-1 is the
same, although i've heard of elusive reports saying that it does work. But how
much working? ALL functions, or only some?
>
> Hex-gang pots?? Have you got a link to the supplier? That sounds interesting.
The DIY-trimpot setup is woth doing but is a royal pain in the arse. I stuffed
up a couple of sets of trimpots before I got them working. I DID, however, get
an email from someone who was going to use a DIGITAL 4-gang pot setup. This to
me sounds like the best way of all - I'll look into it sometime. Going digital
means you can have as many "gangs" as you like, and control them all
simultaneously off a SINGLE analog pot - and all using a small chip! I'll post a
topic on the Circuitbenders.co.uk forum asking about them - I think it was
someone there who mentioned it.
>
> Keep it happening - let me know how you get on! The PPB is definitely worth
it!
>
> Cheers, Graham
>
>
>
>
>
> --- In CasioSK@yahoogroups.com, "luke" <icanfeelmyselfrotting@> wrote:
> >
> > Hi Graham.
> > Thanks for your numerous replies :)
> > The PPB is great and I'm glad of it's size. If it were much bigger, it just
wouldn't fit into the sk1.
> >
> > I'm running the sk and PPB from an adaptor. It's set to 6volts but puts out
close to 8v. I've not tried with batteries as of yet but I'll give it a whirl.
> > I'm hoping to internally mount the PPB in the speaker cavity as it is the
most spacious and isolated area in the SK1.
> >
> > I need to replace some wires with shielded cable and tidy up the under-board
jumpers. Will shielding the cutoff pot wires be necessary?
> >
> > The output from the PPB is just hooked up to a jack socket and fed into my
mixer. I'd prefer to have it internally mixed but I'm unsure how to achieve
this.
> >
> > The 4th channel issue was solved. I had hooked it up to the point labelled
in the Files section. I measured the output with my multimeter and it was 1-2v
hotter than the other signals, so I connected it to a point closer to the main
IC and that fixed it :)
> >
> > I've disconnected the PPB entirely for further testing today.
> > The SK only semi-shuts down. The drums can still be heard, but no keyboard
can be heard. This is aslo true without the PPB connected.
> > I'm not overly sure if this particular SK was faulty before I opened her up.
> > I had the PPB wired to the 7.5 of the amp IC... perhaps this would this
cause more hum...
> >
> > I contemplated stacking trimpots for a crude 4-gang. I'm still tempted. With
the 5534s, the 2 dual gangs are a lot more usable than the 741s. I've seen some
hex-gang pots on ebay for cheap from China. They're triple-deck, apparently and
look like 3 dual-gang pots piggybacking. They're also cheap at £3 a pot.
> > Cogs n' gears had crossed my mind, but I'm not sure I have the skills or
tools for the job. It would be beautiful though.
> >
> > Thanks for all your help and advice Graham. I'll post my results soon.
> > Cheers!
> > Luke
> >
> > --- In CasioSK@yahoogroups.com, "gmeredith1" <gmeredith1@> wrote:
> > >
> > > Hi Luke,
> > >
> > > Graham here, the designer of the Phat philter Bank. Sorry I missed your
posts, gosh, I go away for a few days and this place gets exciting :D
> > >
> > > Glad you got the PPB working, I apologise for making it so cramped a board
layout - I did this so I could mount the full quad board internally without
having to ditch the speaker. One day I'll do a larger, more mistake-proof
layout.
> > >
> > > Regarding the squeal - I found that the 741's did exactly that, too - they
are sensitive to the resonant point on the res pot much more than the 5534's.
The 5534's are much cleaner sounding as well, so thy're better all round. They
are also more sensitive and have higher gain - and so they'll pick up hum more
than the 741.
> > >
> > > Mine does hum but only ever so slightly, and you only notice it when you
turn up the volume past half-way. Mine is mounted in an SK-8 internally. Are you
running the SK on batteries or an AC plug pack? The AC plug pack is possibly
making the PPB hum, if you are. Try it on batteries and see if it still does it.
> > >
> > > Is yours internally mounted or separate? Moving mine around inside to
various places created more/less hum. Make sure all your input/output wires are
shielded.
> > >
> > > Are you running the outputs of the PPB directly into an amp, or re-routed
back into the amp in the SK? Mine is re-routed to the SK amp.
> > >
> > > Try using it outside of the sk, if it isn't already, and see if it changes
the hum issue. At the worst case scenario, unhook it completely from the sk and
test it as a standalone filter, powered by it's own battery and test each
channel input for noise. Also, try mounting it inside a metal enclosure to see
if this shields it from hum.
> > >
> > > Regarding the 4th channel being louder than the others - I'm not sure
about it, but one of the SK lines might be a bit louder than the others.
Increase the PPB input resistor to that channel to balance it out with the
others is my suggestion.
> > >
> > > Regarding the sk shutting down, are you powering the PPB directly off the
sk, or from its own separate battery? It sounds like you've connected it to the
Sk internally at a certain place and it's draining the +5V processor power rail
and making it think that the batteries are flat. Is this correct? The PPB best
runs off the 7.5V audio power rail inside the SK, which is separate from the
proccesor power rail.
> > >
> > > Hope that helps, if nothing helps it, disconnect the PPB from the SK
completely and check it, and then reconnect it in stages, checking each channel
and the hum, and the power issue.
> > >
> > > Cheers, Graham
> > >
> > >
> > >
> > > --- In CasioSK@yahoogroups.com, "luke" <icanfeelmyselfrotting@> wrote:
> > > >
> > > > The keys cut out after approx. 400 strokes. Which is rubbish.
> > > > Any advice on this one?
> > > >
> > > > On the PPB, I replaced the 741s with 5534s and it has cut the squealing
completely, I am now experiencing a great deal of hum instead, which is as
annoying as the squeal but not as deafening.
> > > > I imagine it's a loose ground somewhere or some additional caps are
needed or something. The key issue is more vexing.
> > > >
> > > > Sorry for the double post btw.
> > > > Luke
> > > >
> > > >
> > > > --- In CasioSK@yahoogroups.com, "luke" <icanfeelmyselfrotting@> wrote:
> > > > >
> > > > > There's an APO mod on Electri-Fire's site which works a treat. I've
had the demo going for about 20 minutes and the crazy is setting in now...
> > > > >
> > > > > I don't think my issues are APO related.
> > > > > What seems to be happening is the keyboard becomes unresponsive after
about 2-3 minutes of playing. If I up the volume, I can hear some matrix noise,
but no key sounds. The drums are still audible and hitting the demo button
brings the keys back to life. It's strange and annoying.
> > > > >
> > > > > You should try the PPB. It's really nice. Gives the SK1 a whole new
dimension. I think the layout could be made less cramped, but for space saving
GMeredith's layout is as packed as could be.
> > > > >
> > > > > I'll be putting an LTC1799 in too for pitchability.
> > > > >
> > > > > I'll chuck a vid up when she's finished.
> > > > > Thanks again Tanner
> > > > >
> > > > >
> > > > > --- In CasioSK@yahoogroups.com, "noystois" <noystoise@> wrote:
> > > > > >
> > > > > > i dont know, ive never built it. it only turns off 10 minutes after
you last touched the sk1 right? not while youre still playing? ive heard of
people trying to modify the sleep circuit on the sk1 but with no success. seems
like all you would need to do is find a redundant i/o that resets the sleep
circuit and hook it up to an lfo or something. i've done this with other toy
keyboards but never an sk1. it might be kind of hard to find considering you
would have to wait 10 minutes to see if it even works. might be worth it to try
and overclock the sk1 so that the sleep circuit only takes like 1 minute or
something. just some ideas. glad to hear you got the filter working though.
> > > > > >
> > > > > > --- In CasioSK@yahoogroups.com, "luke" <icanfeelmyselfrotting@>
wrote:
> > > > > > >
> > > > > > > Thanks for that Tanner.
> > > > > > > I actually found the source of the problem... I'd placed all of
the res pot wires after a trace cut instead of before it. A rookie mistake
indeed.
> > > > > > > SO now I've relocated the wires and it works, but it's still not
great as the 4th module's signal is much hotter than the others.
> > > > > > >
> > > > > > > I just wish I had quad gang pots. I'm using 2 pairs of dual gang
and it's not ideal.
> > > > > > >
> > > > > > > Other than a few minor issues, the PPB is brilliant.
> > > > > > >
> > > > > > > One major problem I'm having is that the SK stops working after
about 10 minutes. The 'on' LED is still lit but no sound can be made. Does the
PPB affect the auto power off function, or is there a way to disable the APO?
> > > > > > >
> > > > > > > Thanks again for the advice.
> > > > > > > Luke
> > > > > > >
> > > > > > > --- In CasioSK@yahoogroups.com, "noystois" <noystoise@> wrote:
> > > > > > > >
> > > > > > > > i dont think the values of those caps are too critical, they
will just change the tone of the filter. the first thing you could try is adding
a decoupling cap say 100mf from the positve power to the ground. but i think
what the real problem might be is that the signal coming in is too high. you
should try replacing the 470k resistor with a 100k pot with one outer lug going
to the .01mf cap, the other lug going to GND and the wiper going to the signal.
its hard for me to understand the stripboard layout but fortunately i have the
original schematic here. it says to set the cutoff all the way up and the
resonance all the way down and then adjust the volume to the filter so that the
output from the filter is only as loud as the original signal. if you are still
getting too much gain, there may be too much resistance between the -in and the
out but i doubt it, its only 200k. good luck. -tanner
> > > > > > > >
> > > > > > > > --- In CasioSK@yahoogroups.com, "luke" <icanfeelmyselfrotting@>
wrote:
> > > > > > > > >
> > > > > > > > > I've just finished a phat Philter for my SK-1. It seems to be
working reasonably well. However, it squeals like crazy.
> > > > > > > > >
> > > > > > > > > I didn't have any NE5443AN op-amps, so I used 741s instead.
Could this be the root of the problem?
> > > > > > > > >
> > > > > > > > > Also, I had no 470pf caps so I used 560pf as an alternative
and have also tried 390pf, which alters the tone of the squeal but does not
remedy it completely.
> > > > > > > > >
> > > > > > > > > Any ideas or thoughts would be greatly appreciated.
> > > > > > > > >
> > > > > > > > > I'm guessing that changing op-amps would probably be the
biggest help.
> > > > > > > > >
> > > > > > > > > Luke
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
>

Hi Luke,

I'm glad you resolved the hot 4th line, that's great! Perhaps when you get time
you could show the connect points for the SK1 in a photo or something for those
with an SK1.

Regarding powering it, running it off the 7.5V amp line like you had is the best
place to run it for a number of reasons - the main one is that this voltage line
completely powers down when you switch the SK1 off, whereas the 5V line is
always on, even with the power turned off - to retain the processors settings.
On the SK8 it remains powered to also retain the 4 sample memories when switched
off. Hooking the PPB up to the 5V rail will cause the PPB to not switch off and
so drain your batteries whilst switched off.

If you were running it off the power pack it might make the PPB hum a little if
the power pack is a bit rough in its AC smoothing. That's just a guess - you
could try running the SK-1 off batteries to see if this helps. If it doesn't,
try the pot wire shielding - it can only help. The other thing you could do is
try wrapping the whole PPB in foil, with a connection from the foil to a ground
point on the PPB board (Make sure you wrap the board in plastic wrap first to
insulate it from the foil). It's worth a try. Maybe you could email me a mp3 of
the hum whilst, say, playing a rhythm so I can see how much there is.

The other hum source could be the SK1 circuit board itself - namely the
processor - being a computer, it emits electromagnetic radiation that can
interfere with unshielded audio circuits. Mine hummed more or less in certain
parts of the casing, even when running everything off batteries. Not much, and
only when turned up a lot, but you could hear that it was more than the SK1 by
itself. I seem to recall testing the PPB externally before fitting it, running
it off batteries and also the sk off batteries and hearing no hum - I only
noticed the hum when I finally mounted it in the casing and recalled not hearing
it before.

The SK1 shutdown problem - I suspect it's related to the shutdown mod. Try
reversing the mod and put the SK back to stock condition and try it first.

I've never been totally convinced that this mod works on the SK-1. On the SK-8,
it is impossible to implement, because the SK-8 processor itself will shut down
after 7 mins even if you do the mod to it - I tried and tried and bought the
service manual and tried but to no avail. You can get the analog section to stay
awake, and everything LOOKS like its still awake, but the proceesor goes to
sleep and the keyboard becomes unresponsive even though all the lights are on
and you can hear hiss from the speaker. On the SK-8, this is because the
shutdown timer is built-in to the processor chip itself - it's not an external
device disabled by cutting a trace. And somehow, I think that the SK-1 is the
same, although i've heard of elusive reports saying that it does work. But how
much working? ALL functions, or only some?

Hex-gang pots?? Have you got a link to the supplier? That sounds interesting.
The DIY-trimpot setup is woth doing but is a royal pain in the arse. I stuffed
up a couple of sets of trimpots before I got them working. I DID, however, get
an email from someone who was going to use a DIGITAL 4-gang pot setup. This to
me sounds like the best way of all - I'll look into it sometime. Going digital
means you can have as many "gangs" as you like, and control them all
simultaneously off a SINGLE analog pot - and all using a small chip! I'll post a
topic on the Circuitbenders.co.uk forum asking about them - I think it was
someone there who mentioned it.

Keep it happening - let me know how you get on! The PPB is definitely worth it!

Cheers, Graham





--- In CasioSK@yahoogroups.com, "luke" <icanfeelmyselfrotting@...> wrote:
>
> Hi Graham.
> Thanks for your numerous replies :)
> The PPB is great and I'm glad of it's size. If it were much bigger, it just
wouldn't fit into the sk1.
>
> I'm running the sk and PPB from an adaptor. It's set to 6volts but puts out
close to 8v. I've not tried with batteries as of yet but I'll give it a whirl.
> I'm hoping to internally mount the PPB in the speaker cavity as it is the most
spacious and isolated area in the SK1.
>
> I need to replace some wires with shielded cable and tidy up the under-board
jumpers. Will shielding the cutoff pot wires be necessary?
>
> The output from the PPB is just hooked up to a jack socket and fed into my
mixer. I'd prefer to have it internally mixed but I'm unsure how to achieve
this.
>
> The 4th channel issue was solved. I had hooked it up to the point labelled in
the Files section. I measured the output with my multimeter and it was 1-2v
hotter than the other signals, so I connected it to a point closer to the main
IC and that fixed it :)
>
> I've disconnected the PPB entirely for further testing today.
> The SK only semi-shuts down. The drums can still be heard, but no keyboard can
be heard. This is aslo true without the PPB connected.
> I'm not overly sure if this particular SK was faulty before I opened her up.
> I had the PPB wired to the 7.5 of the amp IC... perhaps this would this cause
more hum...
>
> I contemplated stacking trimpots for a crude 4-gang. I'm still tempted. With
the 5534s, the 2 dual gangs are a lot more usable than the 741s. I've seen some
hex-gang pots on ebay for cheap from China. They're triple-deck, apparently and
look like 3 dual-gang pots piggybacking. They're also cheap at £3 a pot.
> Cogs n' gears had crossed my mind, but I'm not sure I have the skills or tools
for the job. It would be beautiful though.
>
> Thanks for all your help and advice Graham. I'll post my results soon.
> Cheers!
> Luke
>
> --- In CasioSK@yahoogroups.com, "gmeredith1" <gmeredith1@> wrote:
> >
> > Hi Luke,
> >
> > Graham here, the designer of the Phat philter Bank. Sorry I missed your
posts, gosh, I go away for a few days and this place gets exciting :D
> >
> > Glad you got the PPB working, I apologise for making it so cramped a board
layout - I did this so I could mount the full quad board internally without
having to ditch the speaker. One day I'll do a larger, more mistake-proof
layout.
> >
> > Regarding the squeal - I found that the 741's did exactly that, too - they
are sensitive to the resonant point on the res pot much more than the 5534's.
The 5534's are much cleaner sounding as well, so thy're better all round. They
are also more sensitive and have higher gain - and so they'll pick up hum more
than the 741.
> >
> > Mine does hum but only ever so slightly, and you only notice it when you
turn up the volume past half-way. Mine is mounted in an SK-8 internally. Are you
running the SK on batteries or an AC plug pack? The AC plug pack is possibly
making the PPB hum, if you are. Try it on batteries and see if it still does it.
> >
> > Is yours internally mounted or separate? Moving mine around inside to
various places created more/less hum. Make sure all your input/output wires are
shielded.
> >
> > Are you running the outputs of the PPB directly into an amp, or re-routed
back into the amp in the SK? Mine is re-routed to the SK amp.
> >
> > Try using it outside of the sk, if it isn't already, and see if it changes
the hum issue. At the worst case scenario, unhook it completely from the sk and
test it as a standalone filter, powered by it's own battery and test each
channel input for noise. Also, try mounting it inside a metal enclosure to see
if this shields it from hum.
> >
> > Regarding the 4th channel being louder than the others - I'm not sure about
it, but one of the SK lines might be a bit louder than the others. Increase the
PPB input resistor to that channel to balance it out with the others is my
suggestion.
> >
> > Regarding the sk shutting down, are you powering the PPB directly off the
sk, or from its own separate battery? It sounds like you've connected it to the
Sk internally at a certain place and it's draining the +5V processor power rail
and making it think that the batteries are flat. Is this correct? The PPB best
runs off the 7.5V audio power rail inside the SK, which is separate from the
proccesor power rail.
> >
> > Hope that helps, if nothing helps it, disconnect the PPB from the SK
completely and check it, and then reconnect it in stages, checking each channel
and the hum, and the power issue.
> >
> > Cheers, Graham
> >
> >
> >
> > --- In CasioSK@yahoogroups.com, "luke" <icanfeelmyselfrotting@> wrote:
> > >
> > > The keys cut out after approx. 400 strokes. Which is rubbish.
> > > Any advice on this one?
> > >
> > > On the PPB, I replaced the 741s with 5534s and it has cut the squealing
completely, I am now experiencing a great deal of hum instead, which is as
annoying as the squeal but not as deafening.
> > > I imagine it's a loose ground somewhere or some additional caps are needed
or something. The key issue is more vexing.
> > >
> > > Sorry for the double post btw.
> > > Luke
> > >
> > >
> > > --- In CasioSK@yahoogroups.com, "luke" <icanfeelmyselfrotting@> wrote:
> > > >
> > > > There's an APO mod on Electri-Fire's site which works a treat. I've had
the demo going for about 20 minutes and the crazy is setting in now...
> > > >
> > > > I don't think my issues are APO related.
> > > > What seems to be happening is the keyboard becomes unresponsive after
about 2-3 minutes of playing. If I up the volume, I can hear some matrix noise,
but no key sounds. The drums are still audible and hitting the demo button
brings the keys back to life. It's strange and annoying.
> > > >
> > > > You should try the PPB. It's really nice. Gives the SK1 a whole new
dimension. I think the layout could be made less cramped, but for space saving
GMeredith's layout is as packed as could be.
> > > >
> > > > I'll be putting an LTC1799 in too for pitchability.
> > > >
> > > > I'll chuck a vid up when she's finished.
> > > > Thanks again Tanner
> > > >
> > > >
> > > > --- In CasioSK@yahoogroups.com, "noystois" <noystoise@> wrote:
> > > > >
> > > > > i dont know, ive never built it. it only turns off 10 minutes after
you last touched the sk1 right? not while youre still playing? ive heard of
people trying to modify the sleep circuit on the sk1 but with no success. seems
like all you would need to do is find a redundant i/o that resets the sleep
circuit and hook it up to an lfo or something. i've done this with other toy
keyboards but never an sk1. it might be kind of hard to find considering you
would have to wait 10 minutes to see if it even works. might be worth it to try
and overclock the sk1 so that the sleep circuit only takes like 1 minute or
something. just some ideas. glad to hear you got the filter working though.
> > > > >
> > > > > --- In CasioSK@yahoogroups.com, "luke" <icanfeelmyselfrotting@> wrote:
> > > > > >
> > > > > > Thanks for that Tanner.
> > > > > > I actually found the source of the problem... I'd placed all of the
res pot wires after a trace cut instead of before it. A rookie mistake indeed.
> > > > > > SO now I've relocated the wires and it works, but it's still not
great as the 4th module's signal is much hotter than the others.
> > > > > >
> > > > > > I just wish I had quad gang pots. I'm using 2 pairs of dual gang and
it's not ideal.
> > > > > >
> > > > > > Other than a few minor issues, the PPB is brilliant.
> > > > > >
> > > > > > One major problem I'm having is that the SK stops working after
about 10 minutes. The 'on' LED is still lit but no sound can be made. Does the
PPB affect the auto power off function, or is there a way to disable the APO?
> > > > > >
> > > > > > Thanks again for the advice.
> > > > > > Luke
> > > > > >
> > > > > > --- In CasioSK@yahoogroups.com, "noystois" <noystoise@> wrote:
> > > > > > >
> > > > > > > i dont think the values of those caps are too critical, they will
just change the tone of the filter. the first thing you could try is adding a
decoupling cap say 100mf from the positve power to the ground. but i think what
the real problem might be is that the signal coming in is too high. you should
try replacing the 470k resistor with a 100k pot with one outer lug going to the
.01mf cap, the other lug going to GND and the wiper going to the signal. its
hard for me to understand the stripboard layout but fortunately i have the
original schematic here. it says to set the cutoff all the way up and the
resonance all the way down and then adjust the volume to the filter so that the
output from the filter is only as loud as the original signal. if you are still
getting too much gain, there may be too much resistance between the -in and the
out but i doubt it, its only 200k. good luck. -tanner
> > > > > > >
> > > > > > > --- In CasioSK@yahoogroups.com, "luke" <icanfeelmyselfrotting@>
wrote:
> > > > > > > >
> > > > > > > > I've just finished a phat Philter for my SK-1. It seems to be
working reasonably well. However, it squeals like crazy.
> > > > > > > >
> > > > > > > > I didn't have any NE5443AN op-amps, so I used 741s instead.
Could this be the root of the problem?
> > > > > > > >
> > > > > > > > Also, I had no 470pf caps so I used 560pf as an alternative and
have also tried 390pf, which alters the tone of the squeal but does not remedy
it completely.
> > > > > > > >
> > > > > > > > Any ideas or thoughts would be greatly appreciated.
> > > > > > > >
> > > > > > > > I'm guessing that changing op-amps would probably be the biggest
help.
> > > > > > > >
> > > > > > > > Luke
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
>