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There is some strange noise I have a problem with.It maintains same low level and does not respond to the change in the volume.Let us just say we are between the stations and raise the volume. There will be certain noises, crackling and others. That would be the best comparison to it. It is not loud, and when the set is tuned to the station I can't heat it at all, but with a volume level way down it is heard pretty well. I was told it was the driver tr-r, I tried another one with no positive result.The radio's performance is outstanding otherwise. Do not think it is a band switch. Any ideas? Thanks.
http://www.nostalgiaair.org/PagesByModel...013139.pdf
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Let us know if you have replaced all the electrolytic and paper capacitors and cleaned all controls, switches and tube sockets and tube pins. Could also be a failing carbon resistor, I'd replace all in the audio amplifier section to start.
Then if you have same noise with volume control all the way down, problem is almost certainly after the volume control in the audio amplifier/speaker or voltage divider areas.
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Transformers do not generate noise.
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You might try pulling tubes one at a time, start at the detector and move toward the output and see where the noise stops.
Steve
M R Radios C M Tubes
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Done all of the above, except of sockets and pins. I will checked that, and resistors in the audio.Forgot to mention that it is intermittent, it comes and goes during operation without any external interference.Also,it does not sound as there is a loose contact somewhere,but much softer.
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Codefox,
It was a 1st AF dirty socket pin. Thanks.
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The tube socket pins that go to the plate of the audio output are the highest rate of intermittent noise since these are the hottest pins in the radio with the exception of the rectifier tube.
The Philco phenolic sockets from the early 1930's are terrible; they need to be cleaned and bent for tight contact. Don't rely on contact cleaners when dealing with audio plate contacts; they must be cleaned manually.
Pete AI2V
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Pete,
Thanks. How and what do you clean them with?
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