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My pre-amp overloads my amp

I just bought a used Conrad Johnson PF-R pre-amp. I hooked it up to my Citation 7.1 amp and everything was fine for the first 10 minutes or so. Then my amp clicked off, the red protection indicator light glowed, then the amp came back on. After a while the same thing happened. I stopped playing music and the same thing happens even when no music is playing. Tried it again the next day (not playing anything) and the same thing happens, the amp goes off, then comes back on. The amp works fine with both my other pre-amps so I know the problem is with the CJ. There are no switches or adjustments of any kind that I can see other than the input and output jacks. I'd like to get some idea as to what is going on before I call the seller (Audiogon member)

Thanks,

Steve
say811

Showing 1 response by jcbtubes

jcbtubes
400 posts
 
811- Sean is probably correct in his assumption that the offset voltage on one or both channels of the pre-amp is just high enough to trigger the protection circuit of the Citation. I'm not familiar with the CJ PF-R pre-amp. If it is capacitively coupled on the output, then it is possible that at least one of the output caps needs replacement. If it is DC coupled on the output, then the driver circuit needs to be adjusted or repaired.

Very low-frequency oscillation can also produce this situation. On one occasion, I had a very odd situation where the input circuit protection was responding to low frequency junk caused by a ground loop in a system. However, this is extremely rare.
Good luck.
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