Muse amplifier issue

[wkjeffers]

Hello,

I have a muse stereo amp that has an issue. One half of the output sin wave is distorted on one channel. My local tech spent weeks with it testing output transistors, caps, etc with no luck. He couldn’t find any info about Muse amps so handed it back to me. Anyone here have experience with these amplifiers?

 

[chazix]

No experience, I'm afraid. Mostly sympathy, and regret that nobody with a real clue has come along. Nevertheless, here's a wild guess based on the symptoms and the tech's frustrating hunt:

If this amp features a more-or-less-conventional output current limiting circuit, it may be that that's where the problem lies. I have a case like that "in flight" now, where the output transistors and other high-power parts had been repaired by a previous worker, but the current limiter circuit was faulty and was shutting down the positive-going half of output voltage when the output was loaded with a typical loudspeaker.

It will be hard to know if your amp has a current limiting circuit if there is no schematic available. An uber-tech might be able to figure that out by tracing what is connected to the emitter terminals of the output transistors. (I'm making some major and unfounded assumptions about the design of the output stage.) If there are any connections to the emitter terminals besides some very-small-ohm-value resistors, then there may be a current limiting feature.

In the slim hope that this may help,

chazix

 

[wkjeffers]

I have read this hey had some weird hybrid feedback scheme but not sure about the current limiting. Thanks for the reply.