Korg Polysix Effects speed/intesity knob problem

[mgbs70]

Hello, On the Effects section, my unit's phase/chorus/ensemble selector works fine. However, the knob that adjust the rare/speed has stopped working. All of the effects now just work at the same quick rate - very annoying. Is this an easy fix? Any suggestions would be appreciated. Regards, Jim

[Synthaholic]

It could be as simple as a bad solder joint or a bad pot (the control the knob turns). Or it could be a more serious problem with the circuitry. Have you ever had the battery serviced on your Polysix? If not, it could be leaking and destroying the circuits.

Have you opened it up to take a look yet?

[mgbs70]

Yes...the knob turns and nothing looks out of order inside. there doesn't look to be much that could go wrong here other than the pot, but it seems to turn normally. How would you test this? It does have a new battery which is working fine.

[pflosi]

check IC 30 and 31 on KLM 367. they're responsible to assign the parameters to the knobs, and they're just next to the battery... so they can be easy destroyed by a leaking one

[sam]

Change those chips anyway. I always replace these even if they look ok.

They can be tricky to get out ..Take time for this..

[mgbs70]

Thanks for the help! I think I'm going to have a pro take a look at it. Regards, Jim

[rhino]

chiming in too late maybe.
just finished a Poly repair with a similar (not exact) problem: EG INTENSITY stuck on max. Turned out ot be a shorted cap on the output of IC-18 (1-to-8 demux). This forces the output of the op-amp follower to stay high.
Replaced the IC and no joy. Was ohming traces with both IC-18 and IC-7 (new op-amp) out of their sockets and found the run was a dead short... only thing left was the 0.047 cap. BINGO! Have your tech check C-27 on pin 13 of IC-18.