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MJ1035 sings again...
...but very weakly. I worked on the set for about an hour yesterday (11.13.08) and decided to test it, just to see if the signal circuits were working. When I was tuning across the FM band to check the multiplex circuits (was looking for the indicator to come on when the radio was tuned to a stereo station), I put my ear to the speaker and heard very faint audio from a Cleveland station, in addition to the stereo indicator illuminating. This tells me the volume control must be working well enough to complete the audio output circuit, but there are still issues with the wiper contact as the volume level will not change when I turn the shaft. I'm thinking perhaps the wiper isn't making contact with the resistance element (as old1625 mentioned in a reply to one of my previous posts a few months ago regarding this issue). I have not yet run the ohmmeter test on the control that Chad mentioned in his reply to my last post; perhaps I'd better make that my next step in trying to find this problem. However, I think there is also a defective electrolytic filter cap in the radio's power supply, as there is a 60-Hz AC hum that is much louder than the audio output. If I could get rid of that hum I'd probably find the audio is a bit louder than it seems right now. The MJ1035 has a can-type electrolytic, with three sections. Are replacements for this cap still available after 43 years (my MJ1035 was made in 1965), and if not, is it possible to use one or more caps connected in parallel to replace it? There seems to be plenty of room under the chassis.
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Jeff, WB8NHV
Collecting, restoring and enjoying vintage Zenith radios since 2002
Zenith. Gone, but not forgotten.
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