YAMAHA DX7s schematic


Just fixed lots of broken tracks in my DX7s.
The data rom cartridge was pushed to hard into the slot which resulted in a hairline crack between the two pin rows.
Guess the keybord has been upside down with the cartridge insterted.
Have tried to fix this but some of the banks doesn't work so I probably missed somewere.
Layout of the pcb where the slot is located would be excellent.
Anyone had same problem?

Best regards

The schematic is huge, a large folded thing like a map. No way I could scan it in. It really would be worth your effort to order the service manual from Yamaha. They might charge you $15-25, but you get the complete schematics, the board layouts, the parts lists, the diagnostics, mechanical blowups, test procedures, and whatever else you might need to service them. Yamaha documentation is first rate.
Hi Enzo and thank's for reply!

Yes I know that the schematic is big, got one for the DX7 at work.
15-25$ is not much money I'm not greedy :) , the only thing needed is the layout of the double sided board where the cartridge slot is.
I wouldn' ask anyone to scan the manual if they don't already have it scanned.
The fact is they don't even have the service manual at YAMAHA in Sweden but ofcourse they will probably order one from YAMAHA.
I'll check with them again it's always best to have the complete service manual on hand.
Thank's for your help Enzo.

I know it's been a while since this took place, but I am having a similar problem of my own.
I recently bought a Yamaha DX7s, and assumed it maintaned working condition. Which it hadn't. And that peice of information didn't get to me until I plugged it in.....nothing. So I opened it up, and spent the last 12 hours researching information and clicking a volt-meter to each individual wire to find what works and what dosn't(the problen is in the power supply).
What would really help is the schematic for the power supply for the DX7s. I have found PLENTY of shematics, for the power supply, of the Yamaha DX7, DX7 *Speacial edition Rom*, ect. But not the DX7s. And I couldn't find it on Yamaha's site either. Any suggestions?
Same advice I gave several years ago. It may not be posted on Yamaha's site, but if you contact them in California, they should be able to sell you a manual. Worth the price really.

It's been a while, but I ended up buying it from Yamaha(took nearly a month to ship) and fixed it. The real problem is(I don't know if you can help me with this) but, there are no programed sounds. out of the 64 presets, only 10 of them make a real noise, and that noise is, more often than not, annoying. When I called customer service and all that jazz, they told me,"buy a MIDI cable, that will solve all your problems". At the time I had no idea what that was, so I bought one(of course It wasn't compatible with Vista at the time), but what I really want to do, is to take it with me places and be able to use it, opposed to lugging around computer. Suggestions?
I haven't seen one of those in maybe 20 years. But it sounds like memory is empty and you need to reinitialize it - "restore factory settings." If re-init is not in the service manual, it should be in the owners' manual. And that might be what they meant by using a MIDI cord. They might have been suggesting to download the memory content and then dump it into the DX via MIDI.

Seems to me on the DX7 that running the diagnostics ended with putting memory back to ROM content. Have you run the self-test on this model?
re-init wasn't in the owners manual, and I can't find the service manual online. But I'm curious, how would one use MIDI to fix this problem? I'm still new to the idea of MIDI but I didn't know a stunt like that was possible. Also, how do you preform the 'self-test'?
Your time is appreciated and I thank you for your contribution :)
Self test is in the service manual, not the owners. And if there is a reinit, it should be in that as well. Either of those functions in most things is a matter of holding 2 or 3 buttons while powering up. No, I don;t recall which ones.

MIDI is just a communication protocol. If your instrument needs to communicate with another, MIDI is the universal standard. Some boards cam dump their memory content through MIDI.

For example, the Korg M-1 if initialized comes up with no patches - no sounds. But you can connect it to another M-1 via MIDI and dump the contents of the one into the empty one. And sometomes you can download the data needed into a computer, then using a MIDI interface, transfer that to the keyboard.

Your owner manual should cover sending and receiveing such bulk. It has been awhile, but I seem to recall "system exclusive" as the term. Look for "loading sounds."

ANother route is the plug in card. The regular DX7 has a slot on the panel for a plastic plug in sound card. A plastic thing the size of a couple 9v batteries side by side.
I thought it would be worth mentioning that earlier today when I turned it on, the LCD screen showed "Performance ! Change Battery". Next to the, the voiced number display said '9'. Just a few minutes ago the LCD shows "Voice Change Battery !" and the display show '52'. This gets more confusing by the minute.
I looked into that site more, and it says this about MIDI "If you're looking for a way to send SYSEX files from a PC to a DX7, there is a very cheap fully featured commercial sequencer with SYSEX capabilities called Power Tracks Pro Audio available for US$29. "
Is that 'the only way'?
SYSEX = system exclusive

Only way? No, just one of the ways we discussed. Your DX7 has no idea what is on the other end of a MIDI cord. COuld be another DX7, could be a computer, could be a little Yamaha disc storage unit. All it knows is that if you tel lit to accept a SYSEX dump through the MIDI port, it will take it. Or get a sound card and plug in the slot. They are saying the program they referenced is cheap and would serve the purpose.

performance and voice are sections of memory, and it is detecting a low battery in the memory, so when you access one of those, it warns you. There is a coin cell sodlered to the board inside, and it is likely getting low. Gee, after 20 years, you'd think the battery would still be OK... Voice #52 refers to a particular sound patch. performance #9 refers to a performance setup.
SYSEX = system exclusive


You've been more help than anyone or anything on the internet! but, nothing I found is any help with how to make the 'SYSEX' exchange. I've downloaded the original 64 voices. And it mentions that you need a ' musical sequencer' to make the exchange? What is an example of a program that would serve that purpose? Would FL Studio, Propeller Head Reason 4, or Ableton Live work in that way? Or something else? I thought I could just open -my computer, find the keyboard, drop the patches, and be on my way. It seems it's a bit more complicated than I thought, but nothing out of my reach!


2010-04-24 1:52 am
I think the programs you mention, while they may work for this purpose, are severe overkill for this task. I think what you want is called a patch librarian for the DX7, though this may well be a part of a larger program (such as a MIDI sequencer, which thesedays may be part of a digital audio recording package). Patch librarians work by transferring patches (synth tone and whatnot settings) between the PC and the synth through SYSEX messages over MIDI.

And yeah it looks like you need to replace the battery that powers the RAM that holds patches and things. This is much like the "CMOS RAM" powered by a battery in PC's from decades ago, before EEPROM/EAROM/FLASH memory became common for memory that keeps its contents through computer powerdowns.
I fixed the keyboard using SYSEX! It took hours of researching, downloading the right software and patches, but it worked! Bulk Dump'd it, and it was an amazing moment. Only problem: When I unplugged it, it all got erased. No surprise, battery is dead. Next step is too replace it........how'd you do that?
You look on the coin cell. Is there a number like CR3023 on it? I forget which cell is in there, but it is a common type found at Radio Shack EXCEPT it has solder tabs welded to it.

You cannot solder to the battery. But places like Digikey sell batteries with solder tabs. Just look up the battery type and in the search parameters select one with solder terminals.

There may be more than one pattern of solder terminals, so look over the dead battery first. SOme have two legs and some three.


Get a coin cell socket of the size for the battery and solder it to the board, then plain old vanilla coin cells from the store will snap into that.

Either way, that main board has to come out to change the part.