[sdiy] broken oberheim matrix 6r

[Danjel van Tijn]

Hi Guys,

I tried to send this out a while ago but the list was onbiously down.
I recently took a gamble to buy a broken Oberheim matrix 6r.
The unit turns on, receives midi but no sound out. I thought it might
be a problem with corrupt memory data but no amounts of resets or self
callibration have worked (nor has re-programming voices from a PC).
When I run callibration I get the following errors:
Bad Wave 63
Bad Res 63
Bad VcF 63
which basically means that all the voice chips are failing the callibration.

I have tried re-seating all connectors, cleaning the pins of the
cem3396 chips (in case of oxidation), I checked all power rails and
have tried to trace through signals with a scope.
It looks like the CEM3396 chips are receiving the appropriae
corresponding signal changes (e.g. if I edit a parameter I see changes
at the inputs of a voice chip). However, the refference signal to the
chip is very very low amplitude and saw haped. Also I get no audio out
of the voice chips.

What are the chances that all 6 voice chips spontaneously died? I have
ordered a sigle replacement chip to see if that makes a difference for
a single voice.

Any other clues as to what may be wrong???

thanks!
Danjel

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