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Philco 71B Code 125 speaker thumping
#21

Checked all the voltages and they are within specifications. Rebuilt the tone control with new capacitors and there was no change other than it works now at least for toggling tones.
Cleaned tube sockets with Deoxit and pipe cleaners. Again, no improvement. Tested all tubes and they all tested strong. Resistors were in spec as well.
I had planned next to restuff the Bakelites. I had already done the safety capacitors earlier on.
I started with the filter caps in the metal box. Changed all of these out and routed new wires. Eureka, this fixed the noise and brought in volume and reception.
Not that it would have made much difference, I put the new caps on the scope to find the outer foil and put those leads to ground

I want to thank everyone for their ideas and assistance with this radio. Truly it was a learning experience


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RE: Philco 71B Code 125 speaker thumping - by dmblackburn - 02-18-2026, 01:52 PM



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