Jupiter 4 problem - constant sound - can you help?

The Roland Jupiter-4 and ProMars Compuphonic Analogue Synthesizer
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Joined: Mon Jun 20, 2011 10:22 am

Jupiter 4 problem - constant sound - can you help?

Postby Basshoven » Mon Jun 20, 2011 1:18 pm

Hi -

I just dusted off my Dads old Jupiter 4. Thinking it wouldn't work at all it turned out to make a sound, although the hold button was busted so it wouldn't stop. I fixed the hold switch and now it turns out that one of the oscillators basically constantly produces a tone. At first I thought it was a dodgy key but I am sure the problem is within the oscillator.

To explain, when the synth is turned on it is always holding one very high note. when in Unison mode, when the key is released the tone continues to play, albeit weaker, so 3 oscillators are turning off and one isn't' In poly mode, the tone of the broken held note changes every time a fourth key is pressed, effectively going thought the other three oscillators before resetting the tone of the broken one as and when it is needed.

Basically I hope this makes sense and was wondering if anyone knew what the problem could be and if it is easily fixable?

How would one go about disabling the oscillators one by one in order to determine which is the dodgy one?

I hope someone can help!

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