Yamaha DX7 Mk1 Cart Write Issues

Hi, I’m new to synths and I’m having some trouble with my DX7 Mk1- it works and sounds fine, but I need help troubleshooting a problem with a RAM cartridge.

I bought this particular keyboard about eight months ago on FB marketplace; it had been imported from Japan (so it’s 100V for what that’s worth) and the seller had told me that the RAM was corrupted among other things but didn’t provide me with any more details than that. I took it home and reloaded factory patches from my computer and it’s been fine ever since. Battery voltage reads 2.8V so I don’t believe that will be a problem any time soon.

Flash forward to about a month ago and I decided to order a RAM cartridge from a vintage synth retailer just to have a larger library of voices without relying on having my computer nearby. It’s an MAARTISTS M128-X 128 voice cartridge (I really just liked the way it looked, what can I say) but when I finally got my hands on it, my keyboard can’t reformat it- I just get a “WRITE ERROR.” Since I don’t know anyone else with a DX7 (or anything in the same family) I haven’t been able to fully test the cartridge. I already tried cleaning the contacts on the cartridge board and the synth with some rubbing alcohol on a cotton swab to no success.

Are there any good ways to troubleshoot this issue without testing the cartridge on another keyboard? I’ve got a multimeter and some basic soldering experience so I’m not afraid to dig into the guts of either the cartridge or the synth to root out the cause.

Thank you for any help!

At 2.8V the coin cell on the motherboard will need changing.

Second the power supply will need investigating for electrolytic cap replacement. All caps in a DX7 are time expired.

Third, if you are using a 100V unit on a 120V power system - the power supply is being overcooked unless you are using it with an external transformer.

or

If the power supply has not been converted, take it to a tech who can do that.

If there is already a data card fault that happened from its time in Japan, that requires the bus and virtually every logic chip in the synth to be examined and fault tested. Mos tech’s will admit defeat when it comes to a bus/ logic failure as it takes too much time to be an economical repair.

If you want to try get a logic probe and a schematic and look for missing logic you can try it, BUT you will never understand how the bus works, you can only look for missing logic operations, or what should be there and isn’t to diagnose faulty parts.

and no, spare motherboards are not available.

Thanks for your response and sorry for the delay in mine, I have been working on other projects for the past couple of months.

I thought the battery would be fine but I knew that the power supply cap needs to be replaced, so I’ll be sure to add a battery upgrade kit to my list and make it easier next time the battery goes dead on me.

I’m using a 100V external transformer that was given to me when I purchased the synth. That works fine with me, and if it doesn’t I might order a power supply conversion kit since it seems like a modification I should be able to handle.

If the cartridge write issue is more likely than not due to a logic problem then it’s not worth fixing for me. I paid almost as much for the RAM cartridge as I did for the keyboard itself, so if it’s a fully functional DX7 that can’t read cartridges I’m fine leaving it at that and maybe buying one in better shape down the line. I just wasn’t sure if this was a semi-common problem with a usual fix or a more unique ghost to chase which is why I came here to ask.