Moog Rouge sound output

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ColinMcIntyre
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Joined: Sat Jan 22, 2022 1:11 pm

Moog Rouge sound output

Post by ColinMcIntyre » Sat Jan 22, 2022 1:15 pm

Have resurrected a Moog Rougue after sitting for 30 years in a garage. Was working perfectly until this afternoon when the sound output failed. Can hear the sound very faintly through the amp, but almost imperceptible. Power is fine.
Any ideas as to what may have gone wrong?

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analogmonster
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Re: Moog Rouge sound output

Post by analogmonster » Tue Jan 25, 2022 2:49 am

I assume a dead opamp, and the thin sound is a side effect. I had this effect when playing a certain time on a prodigy which was retired for a long time and was reactivated by me.
If you want to repair it yourself (and you know what you do, eletrically spoken!): Obtain a service manual from the net and check the input and ouput signals of the opamps of the signal path with a scope back to to the saw core (U7, CA3046), meaning the output buffer (OUT U17E, 4556) <= (VCA U16, 3080) <= VCF etc.
The circuit is quite similar to the prodigy circuit, so this should work to find the problem location.

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