Yamaha DX100 ROM/Firmware image?

[Krankenhaus]

Hi all,

Today I decided to dig out the DX100 that has spent the last 20 years stashed away and have a go at trying to repair it. Basically, it stopped working after I was using it with my Atari ST (yes, it was that long ago!), the ST had a slightly dodgy power cable and would sometimes crackle a bit. Anyway, it did this one day and ever since the DX has refused to work.

It turns on with the power LED but the first 8 characters in the display are just black boxes and nothing else, no sound, nothing.

I have changed the CR2032 battery but that made no difference so it leads me to believe that somehow the EEPROM has gotten fried or the data has been corrupted. I was under the impression that there were measures in place to protect ICs from being damaged with the TLP552 optocoupler? Looking at the schematic the ROM chip is directly below the MIDI in socket.

This is a long shot, but does anyone happen to have the firmware image from a DX100 available? I can source the replacement EEPROM and burn a new one no problem. Or even still, would someone be willing to extract the image from their machine? It' s a big ask I know, especially from a n00b but I do expect to be participating a lot from now on since I have started the electronics again.

Thanks in advance for any info or help.

Edit to add, I can attach the schematic as an attachment if anyone wants a look, as long as I am allowed to do that?

Cheers.

[Circuitbenders]

I can pretty much guarantee that its not a problem with the OS eprom. Its possible, but its extremely rare for something in the OS to be corrupted.
I think it might have been coincidence that it died while your ST was having problems. I suspect that any issue that could send any damaging voltage down a midi cable, would have fried the ST completely before it even got to that point.

have you tired a factory reset? On some machines you'll have to do a reset after replacing the battery.

Check the power rails are showing the right voltage.