Zenith AM/FM radio loses signal.

[Chad Hauris]

I would replace the selenium rectifier in the power supply with a silicon diode with a 50-100 ohm 10 watt resistor in series with it. Was working on a Magnavox 50's FM set that would not tune above 98 mhz and the FM sensitivity was really poor: replaced the selenium with new silicon diode and performance is much better.

[Nick_the_'Nole]

I have one with the same chassis that was doing the same thing. I replaced one of the tubes, I think it was the 12AT7, and the problem went away completely. Also seems to pick up stations clearer now, but that might be my imagination...

Originally Posted by Nick_the_'Nole

I have one with the same chassis that was doing the same thing. I replaced one of the tubes, I think it was the 12AT7, and the problem went away completely. Also seems to pick up stations clearer now, but that might be my imagination...

Thanks for the suggestion. I replaced it with a new production Ei 12AT7 tube and the problem has gone away completely.


Looks like I'm back in business.



Joe

[Jeffhs]

Originally Posted by Chad Hauris

I would replace the selenium rectifier in the power supply with a silicon diode with a 50-100 ohm 10 watt resistor in series with it. Was working on a Magnavox 50's FM set that would not tune above 98 mhz and the FM sensitivity was really poor: replaced the selenium with new silicon diode and performance is much better.

Chad, I have a 1963 Zenith radio with a selenium rectifier. The set still works well, no problems (yet) with the rectifier or anything else. Sensitivity is great, it sounds fantastic, so I really don't want to go into it unless I have to. What could go wrong with a selenium that has been working well for 41 years, no problems? I would think if the thing hasn't shorted by now, it should go for years. I always thought the only way seleniums ever went bad was if they were accidentally shorted (as you once mentioned happened to a Zenith radio you had, in which a headphone jack worked loose and fell on the stack); never thought they could short or open on their own.

I have heard when they start to go bad they smell like rotten eggs or burning sulfur. Never smelt one this bad, but I do agree they should be upgraded with silicon.