Re: [yamahablackboxes] Need newer rom version for tx802
Hello,
I believe that I'm a previous owner of this TX802. I don't have the serial number, but I think that it was 1877. I recently sold a TX802 that had the same condition and the person that I sold it to recently resold it about two weeks ago on eBay.
I toyed with fixing the power-on issue. With an oscilloscope, I noticed that the CL1 (4MHz ceramic resonator) on the Master CPU had no 4MHz square wave when power cycling the switch would not turn on the unit. When the unit turned on right after pressing the power switch, there was always a 4MHz clock signal on the EXTAL (pin 3 of IC1 Master CPU). Possibly replacing this 4MHz ceramic resonator and the two 22pF capacitors would fix it. Or making an external 4MHz clock source, such as a 4MHz crystal with a 74HC14 inverter used as a oscillator, or
the clock out of an inexpensive 8MHz AVR CPU divided by a flip-flop. Then connect this external 4MHz square wave to the EXTAL pin 3 of the Master CPU.
A 32K EPROM such an old 27C256 should work, as might a 32K EEPROM for the OS upgrade. An EEPROM if one could be found for cheap that fit into the original pinout, would be better because it is much easier to make an EEPROM programmer than a EPROM dev system (which needs an ultra-violet eraser as well as a device programmer).
I used to get a lot of 1Mbit (128K bytes) EEPROMs from discarded very old PC motherboards. They held the BIOS code and were in sockets. I built a EEPROM reprogrammer from an AVR Mega162 microcontroller. This might be a cheap alternative to a ExPROM development system. The pins of a 1Mbit EEPROM are the same as a 27C256 in the region between pins 3 and 30. A 1Mbit EEPROM would fit into the socket of a
27C256 but there would have to be a wire jump betweens pins 30 and 32. I'll try this if I needed a 27C256 and only had a 1Mbit EEPROM. But I'm cheap and crazy.
Alan Probandt Portland, OR USA alan_probandt@...
--- On Fri, 6/26/09, Nick Terlesky <Nickster777@...> wrote:
From: Nick Terlesky <Nickster777@...> Subject: [yamahablackboxes] Need newer rom version for tx802 To: yamahablackboxes@yahoogroups.com Date: Friday, June 26, 2009, 10:43 PM
Hi, all.
I just got a TX802 on ebay that has the original rom in it. It will not accept performances 33 through 64 from my G10c (the Yamaha synth-guitar controller unit)... this was a known issue with the v1.0 firmware.
I don't own a Prom burner, so my 1st choice (best hope) is that someone out there has a v1.5 or v1.6 burned onto a chip which they could sell.
Failing that, If anyone has (or can point me to) the latest firmware image, I guess I could buy or build a burner.
Thanks in advance.
Nick.
p.s. Also,this particular unit (tx802),if left turned off for more than a day, doesn't want to bootup until 6-12 tries. I just get black block across the width of the 1st line of the display. Any info on this would be welcome, indeed.
Hi, all. I just got a TX802 on ebay that has the original rom in it. It will not accept performances 33 through 64 from my G10c (the Yamaha synth-guitar...
Thanks, Loscha ! Oddly, I couldn't click on filesuntil I started this reply. Now I can. I am in west-central New Jersey, USA, on the border of Pennsylvania. ...
Hello,  I believe that I'm a previous owner of this TX802. I don't have the serial number, but I think that it was 1877.  I recently sold a TX802 that...
HOLY SMOKES! It's a small world inside these black boxes! Yes, I do have your (ex)TX802 S/N:TMO1877 I'm impressed (not that easy) and grateful (rare) for all...
Greetings: I suspect you have a dead or low battery. Two things to try. One reset the system -- instructions follow. Secondly, turn it on, if it does not...
Greetings again: It looks like V1.5 and it is a three chip set. Again, I don't recall why off hand, but I think there are four total, but for some reason, one...
Hi Peter, ... TX802 OS is stored in three eproms: XB223 - IC11 (Slave) XB224 - IC6 (Main) XB536 - IC10 (Wave) If XB223 (Slave) and XB536 (Wave) are labeled...
HI Peter, There is a message from a once removed previous owner of this exact TX802, down the thread 2 or 3 messages. It looks like a clock doesn't always want...
Please tell Trogdor... No worries. Peter Bye cooked a couple up today & is sending them in the morning. I think he is a couple'a 10-thousand miles closer too....
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