Welcome Guest! Be sure you know and follow the Phorum Rules before posting. Thank you and Enjoy! (January 12) x

Thread Closed
Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5

-11 vdc at point j ?
#1

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



Users browsing this thread:
[-]
Recent Posts
philcorepairbench.com - shadow-meter
Thanks Ron.fenbach — 02:43 PM
Model 70 Cabinet Trim
Thank you, Gary. Before making my original post, I had clicked on "Steve Davis Cabinets" only to find that it...musar — 02:25 PM
philco predicta
Welcome to the Phorum, cgl18! I am not your resource for television repair, but lots of friendly help is available here...GarySP — 02:12 PM
Model 70 Cabinet Trim
Welcome to the Phorum, musar! You can send Steve Davis a private message (PM). The site is at the top of the Home page...GarySP — 02:09 PM
Model 70 Cabinet Trim
How do I contact him? The only contact information for him I could find when searching online was a telephone number th...musar — 10:38 AM
philco predicta
Hello, good afternoon, I would like to ask what the possible problem could be if I don't have an image on the screen. I ...cgl18 — 10:19 AM
Philco model 38 code 121 not receiving signal.
So one last question before I finish this radio. Regarding the speaker and output transformer. I salvaged the original o...Stormlord5500 — 09:31 AM
462ron
It’s on the bottom of the homepage of our Philcoradio.com homepage! Ron462ron — 07:20 AM
Model 70 Cabinet Trim
Steve might have some trim left. Not sure he is making anything.morzh — 06:12 AM
Model 70 Cabinet Trim
Hello musar, First all welcome to the forum and yes that is true that steve stopped making trim . Sincerely Richar...radiorich — 12:13 AM

[-]
Who's Online
There are currently 558 online users. [Complete List]
» 1 Member(s) | 557 Guest(s)
Avatar

>