02-09-2023, 11:49 AM
Let's take a dive in and see what we can find. Here's the service info: https://philcoradio.com/library/download...%2085A.pdf so we can be on the same page.
Starting at the p/s check #'s 48 and 51 the + side goes the filter choke & #50. The - side to the hv center tap. Did you replace or remove #50? If it's original it's probably shorted. This does no damage but will make the filter choke of no effect in the circuit. This will cause hum as will a grounding - side of the filter caps.
Never power the chassis up without the speaker plugged in. You can easily damage the filter caps. If you have to remove the 80 tube this prevents any hv dc voltage. With the spkr plugged in measure the dc voltage from B- (- side of one of the filter caps) to one of the filament pins of the 80 tube. Should see about 275v or so. Then check the voltage over on pin 2 of each the 47 tubes.
Starting at the p/s check #'s 48 and 51 the + side goes the filter choke & #50. The - side to the hv center tap. Did you replace or remove #50? If it's original it's probably shorted. This does no damage but will make the filter choke of no effect in the circuit. This will cause hum as will a grounding - side of the filter caps.
Never power the chassis up without the speaker plugged in. You can easily damage the filter caps. If you have to remove the 80 tube this prevents any hv dc voltage. With the spkr plugged in measure the dc voltage from B- (- side of one of the filter caps) to one of the filament pins of the 80 tube. Should see about 275v or so. Then check the voltage over on pin 2 of each the 47 tubes.
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got it!
Terry
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