Hello, I’m repairing a DX7IIfd which has a dead lowest octave. Taking it apart, I can see corrosion has aided in the breaking of the C1 key’s contact. The metal piece has a clean cut through it near the plastic molding. Would that be the culprit for the while range of keys not working? I was wondering if simply resoldering that piece of metal would solve the problem (doesn’t look like a fun task) or if there was any other work arounds apart from trying to source a whole new key assembly board. Has anyone dealt with this before? Thanks for any help!
Hello, were you able to repair the dead octave? I’m working on a DX7IIFD with 12 dead keys from C#3 up to C4.
Hi, it’s been a while since this took place but if I remember correctly the broken metal piece was connecting that octave to ground and cleaning the corrosion with sandpaper and resoldering this connection fixed problem. I think I actually had to solder a wire between the two metal points because the corrosion was so bad but it did work afterwards.
Thank you for the reply. Did this require disassembling the keyboard assembly itself (removing individual keys, etc)? Or were you able to repair the contacts just by detaching the keyboard assembly from the chassis and working on it intact? I’m wondering if the corroded contact you found is one of those little metal tabs on the underside of the keys.
I’m curious to know whether you managed to get the keys working again.
I have a yamaha keyboard here (not worth repairing) that has groups of keys not working. but was wondering what the problem was, and if it is indeed a small fix or not…
In my case the lowest octave was dead so I only had to remove the keybed from the chassis to access the corroded bit. I think each octave has this metal tab and I’m not sure how easy those would be to get to without removing each portion but reattaching that connection did bring the keys back to life.
If you have groups of dead keys I would remove the keybed and check for corrosion and severed connections. I think I took some photos when I was working on mine - I see if I can find those.
I just dealt with the same problem and successfully repaired it. The only difference is that my dead octave was middle C# to C4. Here’s a summary:
The 61 keys are grouped into five “switch assemblies” (parts 8-2 and 8-3 on the DX7II parts list, page 5), which connect to the keyboard circuit board (part 8-1). There are four 12-key assemblies and one 13-key (the lowest C to C octave. Subsequent ones start at C#). Each one has two metal prongs (one at each end) that are through-hole soldered to the board. I was checking for continuity when I discovered that one of those prongs was detached. The solder joint still looked solid, but when I was attempting to reflow it, the prong fell away. Removing the switch assembly from the board, I discovered that corrosion had eaten right through the prong, cutting it in half. I soldered it back together, reinstalled the keyboard, and the dead keys were back! One flaw remains with the key nearest that prong (middle C#): the output is low. I suspect it’s due to corrosion in that area, which is difficult to remove without completely disassembling the switch assembly.