Discussion about the Korg PolySix synthesizer

Hi, i\ufffdm Stefan from Germany.

I have just a electronic question to you. I\ufffdve got a few days ago a Korg Polysix with already 
done Battery replacement and a new IC31 (74LS08). Now, the programmer works fine, no duplicate 
lighting LED\ufffds or something else but the Knobs won\ufffdt work anymore. The only which works are 
Octave set, waveform, effect mode, tune, bend and volume and the modulators left from te 
keyboard. The other knobs with variable resistors won\ufffdt work anymore.

So i\ufffdve taken another dead polysix and removed his KLM 369+370 and connected it to the other 
one, exact the same Problem. The MG-LED also is flushing but doesn\ufffdt recognize any MG-
Frequency setting. So i\ufffdve thought i have to replace IC30 which i\ufffdve done and after it exact 
the same problem. Now i\ufffdve taken from the old KLM-367-Board the 8048, still the same.

The Internal variable resistors (offset and so on) on the KLM-367 works but the variable 
resistor for "reset" does not working. AFAIK if i tweak him counterwise then normally the 
Board must perform a Reset and all led\ufffds should lighting, but he doesn\ufffdt do that. On the red 
cables are all voltages what the board should get and i also see no destroyed lines.

If i switch the board into "test" mode then the Programmer\ufffds LEDs 4 and 8 Light instead of 1 
and 8, even when i try to correct it with the offset and with resistor. I believe it\ufffds because 
KLM 369 and 370 won\ufffdt work. 

I have at the moment -no- Idea what\ufffds the matter. I study the schematics but can\ufffdt find any 
error on the board-maybe another IC is defective (note: Also the two socked LM13600 were 
replaced).

Do you have any Idea what or which IC can be defect. I can guarantee that the two LS7408 are 
correctly working.

Thanks for your halp!

Stef