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-11 vdc at point j ?
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1929 Philco model 76 filter caps replaced, resistors checked and replaced.  While trying to repair I discovered that the 3872 push pull input
 transformer was open, I ordered and tried to install a replacement transformer a stancor A-53 OR PT-156 from AES . On my radio , point
J where the old transformer was soldered in has a dc voltage of -11 using the chassis as a meter ground point. Using the original wires from 
the old transformer and the new wires  hooked together.
 
1.red wire  (power) -11 volts 
2.blue wire to 27 1st af plate,   Did not hook up
3.green wire #1 to 45 plate 2nd af
4 green wire #2 to 45 plate 2nd af 
5 black wire  to screen grid of 27 1st af.     this wire is a center tap in new transformer between green wires.
 
the radio now has sound from speaker, not good or loud sound but mush mouth understandable sound.
The question is this minus dc voltage normal?  The voltage comes from the power transformer, hv centertap and goes through lug #2 of the
filter caps on the negative side. when changing the caps I used mylar caps NOT electrolitics.
    I am using the philco service manual for schematics and information.  Variac and amp meter also in use. 
                                                                                                       Don


Messages In This Thread
-11 vdc at point j ? - by don hinkley - 09-17-2018, 01:11 PM
RE: -11 vdc at point j ? - by morzh - 09-17-2018, 02:05 PM
RE: -11 vdc at point j ? - by Radioroslyn - 09-17-2018, 03:45 PM
RE: -11 vdc at point j ? - by don hinkley - 09-17-2018, 07:05 PM
RE: -11 vdc at point j ? - by Radioroslyn - 09-17-2018, 07:35 PM



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