Juno 6 'voice' issue

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JFunc
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Posts: 9
Joined: Sat Feb 06, 2016 1:26 pm
Gear: Juno 106, Juno-6, JP-4, A-Juno-2, DX21, CZ-101, 01/Wfd, SY85, X3, XV3080, M1, M3R, D110, MPC1k, S950, Prophecy, Plugiator, TR-8, MFB-522, Volcas

Juno 6 'voice' issue

Post by JFunc » Thu May 19, 2016 3:27 pm

Howdy!

I'm restoring an old Juno 6 at the mo - thanks for all of the help thus far! I have now rebuilt the PSU, and it's now all working bar one voice (voice 3).

When I scope/meter Voice 3 at TP4 (in Test Mode UP - Hold engaged - Note A4) it's not appearing. This led me to check the schematics around this area. After checking the voltages across the pins of a working IR3109 (voice 1) and the IR3109 in voice 3, they're way off. So I assume that the voice 3 IR3109 must be buggered. Damn.

I'm kinda hoping that the BA662 in the VCA stage is OK, but it seems that until I replace the IR3109, I won't be able to check the BA662, as the output of the IR3109 feeds into a BA662. Blast.

There is another BA662 used in tandem with the IR3109 used to control VCF Resonance - but if that had went, then I take it that that voice would stop responding to the Resonance slider?

Anyways, if anyone has had any experience with these old girls, and would be kind enough to chip in with any solid experience - i'd be a very happy chappie!

All the best!

AJ.


Juno 6 CPU Board Schematic (Part) - Image

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