Intermittent Korg DW-6000

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Intermittent Korg DW-6000

Post by JHatzia » Thu Dec 07, 2017 5:43 pm

Patient: Korg DW-6000.

Symptoms: Came into possession with no factory patches, nor sound except for sweeping resonant filter and noise sounds.

Attempted Resolution: Restored patches via sysex (and TAPE just to make sure). Both methods worked and the synth was alive again. After flipping the power the patches were lost. Easy peasy, just a battery replacement. Did the replacement, resent the patches via sysex and now all the waveforms were barely heard. Any key I pressed wouldn't waveforms properly. Only a faint tone very quietly that seemed to play the same tone regardless of which key was pressed. Oddly enough, the filter resonance and noise was still tracking to the keyboard.

I reopened the unit, looked for loose connectors and checked all the +5VDC rails on the second CPU board with the DWGS chips. All chips were getting +5VDC just fine and all connectors seemed legit.

Now after maybe an hour of leaving the unit on, the oscillators came back! Random, but I'll take it.

I decided to leave the unit on all night and this morning the Oscillators were out again. I can tell the patches are still saved because patches like "Thunder" or "Break Dance" which use noise and resonance are working.

Somethings to note with the DW-6000 is that on the Main Voice board there are three ROHM BX7114A board designator chips that are covered in resin just like the JU-106. Possibly these are starting to die after all these years? And on top of it all, I have worked on a different Korg DW-6000 where these chips were not covered in resin as if Korg made an adjustment with later DW-6000s.

This all leaves me wondering if my issue would be coming from the CPU board with the DWGS ICs that generate the waveforms, or if it's occurring on the Main Voice Mixer Board with these resin coated chips, even though noise and resonance are fine. Literally all parameters react fine, but from time to time the waveforms reappear and work.

Info on repairing Korg DW-6000/8000 is few and far in-between, so hopefully we can get solid info gathered with this thread.

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