Quote:
Originally Posted by old_coot88
Bridging simply means "connect in parallel with", using a pair of clip leads. So bridge (jumper) each individual electrolytic (one at a time) with a single unit of equivalent or higher ratings. Note correct polarity.
The caps in question would be C19 and C20 (main power supply filters). You could jumper each with something like a 20mf 450V unit and see if it affects the hum.
EDIT. Those two caps should be replaced as a matter of course anyway. If they're the original cans they could be left in place for aesthetics, but out of circuit. There's also C26, a low voltage electrolytic across the cathode resistor of the 6F6. It won't cause a hum problem, but will cause reduced volume if it's gone open. It should be replaced anyway.
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Its already been done, none of the electrolytics in the radio are original to the set, that was the first thing I did when I got this set, was replace the old electrolytics, which I left the old cans in place for aesthetics and wired in some new electrolytics which I installed onto some isolated terminal strips that I soldered ontop of the old electrolytic can's positive terminal (the terminal strip's attachment lug was isolated from the terminals so the original cans are still out of the circuit but are being used as an attachment point for the terminal strip for the new electrolytics without affecting the circuit, its a trick I learned from Mr. Carlson's Lab.)
I checked the capacitors that I installed in the radio and they still test good yet on my ESR Meter, (they mesured about 4-6 ohms ESR and they both are 2 4.7 MFD 450V axial lead electrolytics paralleled together to make 10 MFD at 450V).
And then the low voltage electrolytic is a 10/10 @ 160V Firecracker type electrolytic cap like the original was, and that one tests fine as well.
So unless one of these caps failed in a manner I'm not aware of, or that the ESR meter wasn't able to detect (dead shorted) then I don't think the electrolytics are to blame here.