Korg Odyssey PPC LFO stuck at near full "ON"

Synth Repair
#1

Hi fellas,

New to the forum. I own many, many vintage and new synths and recently my bought as new, 4 year old Korg Odyssey began behaving strangely with the PPC pad.

In particular the LFO pad. While playing some lead sounds I became aware the PPC LFO began adding vibrato to both OSC’s without pushing the pad.

All switches to LFO are either off or set to the zero position. FM sliders also set to zero. The pad is “Stuck” open and I can’t play anything without the vibrato now. They synth has always been in my studio. Never gigged. Also I usually use the FM sliders for vibrato versus the PPC pad…This happened without warning as there was no detectable “PPC LFO bleed through” prior to.

I’m fairly savvy on my synth maintenance skills. I know these pads work on electrical resistance. Could they possibly just have some oxidation between the pad and the resistor or perhaps the small assembly under the pad is touching the resistor thus leaving it turned on?

Any thoughts would be awesome.

#2

I’m not real familiar with that unit but could It be possible that the middle button between the proportional buttons is hanging?

#3

My thoughts were the same. There is a small, metallic disc encased in the pad. I’m going to open her up later today and see if its causing the problem. To be honest I prefer using the FM sliders to introduce modulation manually versus the PPC so I don’t mind just disabling that disc if possible. Thanks again.