I have like 6 dead keys from middle c down only the white keys don’t work. I think it’s the TMM2365 chip if I replace it does it have programmed? Has anybody had any issues with this?
I have almost the exact same issue. approx. 8 keys are dead. I took it apart, removed all the keys cleaned them. Then I removed all of the Rubber Sound Button Strips. I cleaned all of the contacts with an Eraser first then wiped it all down with Alcohol. I then replaced all of the Rubber Contact Buttons and the issue with the 7-8 keys in the first Octave are still Dead. However 2 of them in the 2nd Octave now work. So cleaning the Contacts works, but I fear there is something electronically wrong now with the 7-or 8 keys that are still not working.
I would clean all of your contacts first. Then re-assemble. Be very cautious when removing the rubber buttons since they are very fragile. There is a YouTube video about this which is helpful.
From Dis-assembly to Cleaning to Re-Assembly, should take about 2 hours. If it still does not work and you need to take it into an electronics repair place you will save approx. 2hours of labor cost since they will not have to clean the contacts. I’m on Long Island and the going rate is $95.00 per hour with a $95.00 bench charge if you do not have them do the work after the estimate, of course they do not charge you if you have them complete the estimated work.
If you come across what your issue is with your JX-3P please let me know. I have had mine since 1988 or 1989… It’s been a while… LOL…
if you have it down to clean,pull the key contact board under the bad keys.Get a well lighted large 5x 10x mag glass and look at the traces closely.its may be dmn hard to see em,but if you find any shiny copper spots, or black discoloration,the traces have been compromised and whil you can run jumpers to fix the traces ,the proper way to fix is replace the board,especially if you dont have soldering skills,which you will need if you expect to fix boards in the future…