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CD-R and Audio Hardware => Audio Hardware => Topic started by: ChronoSphere on 2019-01-19 09:58:20

Title: Old amplifier: low humming on one output, "bleeds through" to others too
Post by: ChronoSphere on 2019-01-19 09:58:20
It's been 5 years since I was able to get my old Soviet amplifier (https://www.dropbox.com/s/g6cxnqiooz2vrus/amp_speakers.jpg?dl=0) working with your help (https://hydrogenaud.io/index.php/topic,100351.0.html). It hasn't popped a fuse since, but recently I noticed a low humming noise on the left channel. This hum is always present on all input channels to a certain degree except one, where the noise is much louder and is present on both channels.

I have tried disconnecting everything but the speakers, but the hum is still present. If anything, disconnecting the input cables actually makes the hum louder. What could be causing this?

I have the full schematic here (https://www.dropbox.com/s/nf320uu0h1xgnu3/amp_scheme_full.jpg?dl=0). I've marked the input selector part of the schematic, do tell if you need more info.
Title: Re: Old amplifier: low humming on one output, "bleeds through" to others too
Post by: Elohe on 2019-01-19 15:50:53
On possible reason and the most probable is dry electrolytic caps. You ned to test them.
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