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Philco Model 38-7: what caps & resistors do fail typically?
#13

Oh, thats why I could not find the choke on the layout. Thanks RodB!

I changed the power cord. Checked resistances. Since everything looked original and in physically good condition I decided to see what happens if I put some voltage on the mains. With a 40W bulb in series, quickly after switch-on I got readings over 200 volts on the B+ supply, dropping to 100 volts after a while. A very faint noise was audible from the speaker, and with antenna I could receive a station.

So I moved on. With a 60W bulb I got good volume and all voltages from the manual are coherent. Could receive a dozen stations with a wire on the antenna. With a 100W bulb I was able to disturb the neighbors... Icon_smile Nothing gets particularly warm. B+ is somewhat below 300 volts.

Thats where I am right now. I apologize for not having listened to all those who suggest to change caps first. I know that this set must not be used in this condition, but its nice to see that not much is at fault. I think the most urgent is the Y-caps on the mains, and check the electrolytics. From then on, if it works and voltages are correct, it should be OK for sporadic & supervised use.

The power switch with its 4 positions seems to modify tonality... couldn't find this in the manual (yet). The leftmost position should be "off", I guess. It does not switch off immediately, only after moving the know a bit in the opposite direction. Is this switch serviceable?

cheers
Martin


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RE: Philco Model 38-7: what caps & resistors do fail typically? - by Musaeum - 06-19-2025, 01:57 PM



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