Quote:
Originally Posted by earlyfilm
Daave,
In addition to potentially bad condensers, also visually check for other problems, like this apparent cold soldered joint.
This Elmenco capacitor may be a replacement, as bad soldering is rather rare on the hand wired Zeniths.
James
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As they say, "Good Catch!" Yes, it could be a cold solder joint and I would replace the cap whilst I was visiting that capacitor.
As for mica capacitors, I would not replace them unless you have a good reason to. They are usually very stable and often still good. Yes, I know that some are starting to cause problems. Important word, "some". They are 50 years old.
Replace those tubular capacitors, one at a time. Test again, do the next one. Test again. You will most likely be rewarded with a good result. Mica caps are usually very low values, not something like .01 µFD. If the markings indicate that it really is .01 µFD then it is a paper capacitor in disguise, not mica and should be replaced. Micamold comes to mind!
If you still have problems, then you may need to trouble shoot and see if a mica cap is causing a problem. Disc capacitors are in the same arena.
I know the temptation is there to replace them all and then test. Trust me, I have done it and regretted it. It is a pain to power up after each replacement. But you can stay out of trouble that way.