OB-Xa Voice Card Problem

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Jacob Hunt
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OB-Xa Voice Card Problem

Post by Jacob Hunt » Wed Aug 24, 2016 2:21 am

Hey all, I'm experiencing a small, (usually tougher to figure aren't they?) but annoying problem with my OB-Xa. One voice card has a problem with VCO 1. I have moved the card around, it is certainly only on one board, one VCO, problem follows the card.

Anyway, the problem is an unsteady, and too low pitch only on VCO1. It consistently tunes significantly too low, different amounts depending on vco tune trimmer (usually between a fifth and an octave), and just has a bit of a "warble" to it. I have already tried swapping all the ICs, no luck. I've also tried recalibrating to no luck.

I was just curious if others have experienced a similar problem and may be able to give some insight before I start searching for the bad part. Thanks in advance for any help.
Last edited by Jacob Hunt on Sat Aug 27, 2016 1:43 am, edited 1 time in total.

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Broadwave
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Re: OB-Xa Voice Card Problem

Post by Broadwave » Wed Aug 24, 2016 9:20 am

If you've swapped the CEM3340 on VCO 1 and you still have the problem, I would check the back of the PCB and clean off any dirt/gunk that may have built up, then turn my attention to trimmers T1, T2 & T3 and R12 (the 1M resistor from the +15 supply)

There's no other active components in that part of the circuit, and passive components rarely fail.

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Jacob Hunt
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Posts: 76
Joined: Wed Mar 09, 2011 10:54 pm
Gear: An old Polymoog that's on it's way.
Location: The Backwoods of Georgia...

Re: OB-Xa Voice Card Problem

Post by Jacob Hunt » Sat Aug 27, 2016 1:42 am

Good call on R12! I pulled it, and measured it, and it was conducting nothing whatsoever. Replaced it, and back to new :D

My OB-Xa and I thank you very much Broadwave!!

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Broadwave
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Posts: 413
Joined: Wed Sep 14, 2011 10:50 am
Gear: Kronos 2-88, Fantom 6, Novation Summit, Modal Argon8X, Yamaha MODX6, Behringer Odyssey, Behringer Poly D, BroadWAVE ARP 2600EX.
Location: Manchester UK
Contact:

Re: OB-Xa Voice Card Problem

Post by Broadwave » Sun Aug 28, 2016 11:13 am

Jacob Hunt wrote:Good call on R12! I pulled it, and measured it, and it was conducting nothing whatsoever. Replaced it, and back to new :D

My OB-Xa and I thank you very much Broadwave!!
Always glad to help ;)

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