Found a jp4 (3 voices working)

The Roland Jupiter-4 and ProMars Compuphonic Analogue Synthesizer
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Joined: Wed Mar 11, 2009 11:23 pm

Found a jp4 (3 voices working)

Postby Composition86 » Wed Mar 11, 2009 11:29 pm

Hi, I have found an half priced Jupiter 4 in very good cosmetic conditions, but seller says that:
by pushing the same key for 4 times, there are 3 notes which are ok and the 4th sounds around an octave lower. It also happens in poly mode.

The synth, in these conditions, should be a full working 3-phonic synthesizer, isn't it?

Which could be the damage? Is it just a question of properly setting the tune's potentiometers on the back (may be with a voltmeter or an oscilloscope) or is there the possibility to have a serious damage? Thanks.

Posts: 11
Joined: Sun Nov 04, 2007 5:53 pm

Postby futility » Sat May 30, 2009 12:51 am

Could be as simple as reseating the offending voice card. The octave of the oscs is stored digitally, so there could be a problem with some specific logic chips on the offending voice card (sorry, can't remember exactly how it works.) Mine had an Osc. out when I got it & it just needed a 555 timer from Radio Shack to bring it back.

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