2. amps-preamps
  3. 994958408

Humming Noise

I have a pair of Don Cochran mono amps. One of them is causing the humming noise to speaker (B&W 801/3). I think one of the caps is leaking but not sure. How do I fix it? Don was out of business. Where do I send the unit for service? I have manual user and schematic. Please help. Thanks so lot in advance.
oanhu

Showing 1 response by bob_bundus

bob_bundus
1,834 posts
 
The first step in this diagnosis is to disconnect all inputs, power back on, then check for the hum. If you still have it then try an AC polarity change &/or temporarily lift the ground with a cheater adapter. If all that fails then you do very likely have an actual problem. Get out your oscilloscope & check the AC ripple on your supply rails, comparing one amp to the other. Suspect the caps at that point if there are radical differences. It could also be a rectifier. Mod guru Andy Bartha can probably take care of this for you.
Andy Bartha Mods
4680 SW 74th Terr
Davie FL 33314
954.583.7866
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