10-13-2025, 01:20 PM
If you want to do a little troubleshooting here's what I'd do. Unplug the set and turn the volume full up. Measure the resistance from the ANT post to chassis ground. Should see a low resistance like 3 or 4 ohms. Higher than that indicates an open primary winding on the ant coil.
Unsolder the wire connected to the wiper on the volume. Measure the resistance from the wiper to ground with a analog meter. Any erratic movement would indicate a dirty or worn out carbon track within. Most of the time it fail near the grounded end of the pot.
On coil #10 find the connection that has a 6000 ohm resistor & a mica cap. Measure the resistance from that point to ground. Should see a low resistance like 3 or 4 ohms Higher than that indicates an open feedback winding on the oscillator coil.
Measure the resistance from the 2nd 77's grid cap to the chassis. Should see about 4 meg. If it's a bit higher it doesn't effect the sensitivity it effects the distortion and selectivity.
Block #20 be sure that the two caps are in the proper order. If switch you'll have muffled and low audio.
https://philcoradio.com/library/download...%20178.pdf
Unsolder the wire connected to the wiper on the volume. Measure the resistance from the wiper to ground with a analog meter. Any erratic movement would indicate a dirty or worn out carbon track within. Most of the time it fail near the grounded end of the pot.
On coil #10 find the connection that has a 6000 ohm resistor & a mica cap. Measure the resistance from that point to ground. Should see a low resistance like 3 or 4 ohms Higher than that indicates an open feedback winding on the oscillator coil.
Measure the resistance from the 2nd 77's grid cap to the chassis. Should see about 4 meg. If it's a bit higher it doesn't effect the sensitivity it effects the distortion and selectivity.
Block #20 be sure that the two caps are in the proper order. If switch you'll have muffled and low audio.
https://philcoradio.com/library/download...%20178.pdf
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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