Archive of the former Yahoo!Groups mailing list: Discussion about the Korg PolySix synthesizer

Hi,

   New member here who has been struggling for years to get a P6 working that was not stored well, and had the typical battery leakage.

It's in good shape, without extensive damage to the KLM 367 board, but all of my attempts to get it working correctly have failed.

    Symptoms are:

1. Does not power up properly with A and 1 buttons lit.

 2.  It is possible to get sound from it, but adjusting any parameters from the MG, EG ,VCO, VCF, Effects or VGA sections causes random Bank, Programmer, Write, and Manual LEDs to light, which produces patches, noises, and sometimes nothing. I can find no pattern to this, except that D4 usually seems to produce a patch of some kind.

3. The Arpeggiator and Key Assign modes seem to work just fine.

   I recently got the mod wheels, and tuning functions working again when I found problems with the traces associated with CN05 pin 12, and its connection to R10 and other components.

   Also pulled VRs 2, 3, 4, 5, 6, and 7, and found more corrosion under them, but fixing that did not seem to change it's behavior much. 

PSU voltages check out fine and are adjustable.

  I have replaced IC 31, and checked all traces to it, as well as IC30 (though I did not replace IC30), and most other ICs on the board. All bad traces I can find were repaired.

Battery was replaced with coin cell holder, as per the Old Crow site.

Based on reading here, I have repeatedly checked all data, and "P" lines for continuity and have not found any problems or shorts.

Everything connected to IC 22 has been checked several times compared to the schematic, and I have noted the errors found in the schematic, as listed on this group.

I would also add that it appears that R83 should switch positions with VR6 on the schematic.

Board has been cleaned and brushed with alcohol to remove any corrosion found.

Multi-pin connectors to the other boards have been tested for continuity and found to be fine.

My questions would be: 

     Can anybody recommend a good way to test ICs 18 and 19? It seems most of the wrong-working controls are connected to these two ICs in some way. They seem to have proper power and ground connections. 

   Same goes for IC 30. Do the symptoms make it suspect? Should I replace it? 

   I've seen folks here recommend the D/A calibration for people with similar problems, but I can't get it to step 2 of the Reset adjustment, where Bank A and number 1 LEDs are lit.

   I'm happy to hear any suggestions of other tests to try, or places to look for a solution. Would love to get this working, and start using it. I DO have an oscilloscope, but am not well versed on it's use, though I am happy to learn.

Thanks in advance for keeping this group going, and any responses.

Jim