Yamaha MOX8 Detuning Issue

Synth Repair
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1

Problem: The MOX8 (without user intervention) drops pitch from time to time in the same session!

Temporary Fix: The player can tape the the Pitch Bar at the position it is in tune with the current song.

Solution(s): The signal does not drop out, it only detunes itself on temporally.

Has anyone seen a similar problem on a Yamaha MOX8? It is not the MOX8 Plus model.

Where should I start? PCB suggestions? Could the Pitch Joy Stick act this way faulty? There is no crackle or lost of signal, just pitch change.

Where would request the Service Manual for the MOX8, i.e., including schematics, signal flow charts, Parts List, etc.?

Thanks for your input,

Billy

2

Faulty pot in the pitch wheel mechanism - get a new one at it’ll fix it. You won’t hear any crackle noises - it’s done digitally by reading a voltage across the pot and wiper. Have seen many pots that go faulty and the voltage across it becoming unstable - I think it’s a problem caused by the pot’s substrate material going bad.