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Moog Source stuck patch
Old 31st January 2016
Gear Head

Moog Source stuck patch

Hi all,

I recently bought a (known faulty) Moog Source that, after a few minutes, changes to patch 7. At this point, you can select another patch, but it immediately switches back.

I'm looking at the schematic, and I'm assuming that something is going wrong with the membrane switch input logic; I haven't had time to probe yet, but that would point to the 74LS378 or the two 4502Bs (and I know 4000 series CMOS has a bad rep for failure). I'm assuming there's a matrix that's scanned by the CPU, but I'm not entirely sure how this works, since there are references to Top Left, Bottom Left, and Bottom Right - can anyone help? Otherwise, I've cleaned the regulator (on the offchance it was the Crazy Source issue), and that hasn't helped.


Old 4 weeks ago
Here for the gear

I'm having the same problem- but with patch 5in my case. It really behaves like a defective membrane switch. Ever have any luck with your repair?
Old 4 weeks ago
Gear Head

Sorry to hear of your problem. IIRC, I bought one of the replica membranes from eBay and that solved the issue in this case.

Assuming the fault is the same, the membranes are fairly rare and expensive at this point (maybe there's one here: If you have a choice, though, eyeball the 'PROGRAMS' font - mine is slightly off compared to the original, and other replacements were closer.
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