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I posted this message on Radio Road but am also posting it here because I think I may get more replies. I hope that I'm not too grossly violating the forum code of ethics by doing this.I've acquired a Grundig 2220U tube radio.
Though I have some experience building tube amplifiers, I have no experience repairing tube radios. Any suggestions on where to start or for good sources on the subject are appreciated.The radio produces no sound or static at all, however:
The radio turns on and all tubes glow (I also tested the EL84 output tube in an amp and it functions properly). The speakers work when plugged in to another source. The tuner dial moves the variable capacitor as it sould.I could perform any other tests required if any repair paths are recommended. I have some tools for testing electronics.
Thanks for your input!
Follow Ups:
Probably a B+ power supply problem. Leaky caps, open HV winding in XFMR or both, etc.Here is a link for a great place to hang out for antique radio discussion.
Thanks for the suggestion and the link. I'll check out the B+ supply...makes sense...
If so test it. Usually the caps start to go and take out the rectifier. An old analog voltmeter like a simpson 260 can often put out enough volts to test old caps for leakage.Personally I'm a shotgun approach type and just replace all caps other then ceramic and mica.
I've checked the HV circuit. It appears OK. So far, the Rectifier holds steady at 335V, the quad cap takes forever to discharge and all of the plates are within range. The rectifier, by the way, is a bridge package that is silver and about the size of a cel phone battery.
Yes - the caps should be replaced regardless, so that's where I'll start. I don't remember seeing a rectifier but I'll check again.
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