[sdiy] Fixing a jupiter 8

[MTG]

>Looking at the service manual, I am thinking it is one of the module
>boards, probaly the GH one? Is there a common failure mode so I can
>just take the board and fix that rather than making him leave his
>synth. It would make me less nervous to take the repaired board back &
>test there, but if the problem is not common I will have to take it
>home to run the full battery of tests.

You are probably right with your guess.  I can't recall for sure, but
some of those synths either had LEDs on the inside indicating the
voice and/or there was a test mode to force the ordering.  In any
event you are going to want a known good channel to compare to,
as well as the power supplies, so take the whole thing.  Get your
hands on an oscilloscope.  It should be fairly easy to follow the 
audio path through the voice and see what's what.

GB