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

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

Philco 39-7C Restore
#1

I started working on the 39-7C I got recently. The link to the schematic is https://philcoradio.com/library/download...20Book.pdf

Overall it looks relatively decent. There is rust on the back of the chassis but most of the chassis is rust free. It has the usual crumbling rubber insulation for this vintage and all the tubes test good except the 6A7. All of the transformers ohm out OK except for the secondary on the antenna transformer. The 5 ohm section between lead 3 & 4 is open. I'm not quite sure what I'm going to do about that.

[Image: https://www.dropbox.com/scl/fi/6i0ljg88d...kieq&raw=1]
[Image: https://www.dropbox.com/scl/fi/06u793mwu...stjl&raw=1]
#2

Looks as if no one has been hacking around in there, so that is a help, good luck.

Paul

Tubetalk1
#3

Bob, yeah. The secondary is critical, as it is part of the tuning.
Is it a simple bobbin, easy to rewind, or one of those "cross-wound" wax-dipped jobs?

People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
#4

I’m not sure Mike. I think I’m going to have to take apart to see. It looks like some kind of sleeve over the windings.


Attached Files Image(s)
   
#5

Might turn out to be not too bad at all. Looks like a regular one-layer coil. The sleeve..I guess you'll find out when it's off. Could be of some simple mechanical purpose.

People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
#6

When I get back to it I’ll let you know, thanks.
#7

This is a Pittsburg PA area radio which is consistent with where it was shipped from. The automatic tuning buttons are set for KQV, WJAS, WCAE, KDKA, and WHJB which according to a 1940 Station Log in our Library are 1380, 1290, 1220, 980 and 620 on the dial. All are Pittsburg stations except WHJB which is Greeensburg (WHJB is currently 107.1 FM in Greensburg).
#8

I finally got back to working on this radio after almost a year. I even forgot that I had already started this thread and that the antenna transformer has a problem. As I mentioned earlier the wire insulation is crumbling for almost every wire in the set. The power transformer got my attention first and indeed there has been some heat I think.

[Image: https://www.dropbox.com/scl/fi/zbomdctv6...x2b4&raw=1]
#9

39-7 should have the same or very close transformer as 38-12, and the junk chassis are many and available, in case you need one.

People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
#10

Thanks Mike. It actually seems to be ok, at least it ohms out ok with no shorts. I will try getting the wires reinsulated.
#11

Bob

Transformer may heat up for reasons that are not its own; it could be loaded heavier than appropriate.
But if it did not sustain damage, it could be OK.
To me a good way of testing it is plugging it in 120V and running it with no load. If it does not heat up (could get a tad warm) considerably, it is OK (no turn short).
Ohming out is the first check, of course, but it will not reveal a turn short.
This test will.
(BTW this is one instance where I approve using a dim bulb tester).

People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
#12

Thanks Mike, I will do that check. Just a bit of progress today but ready to put the shell back on and reinstall the power transformer now. I simply took off the old insulation by squeezing it a little with needle nose pliers. It just crumbled away. Then a colored heat shrink sleeve went over the uninsulated wire. I spliced in a longer piece of wire that will then get soldered onto the appropriate spot on the chassis. A quick ohm check after all the work and it still seems to be OK.

[Image: https://www.dropbox.com/scl/fi/oauwtcj0g...5bug&raw=1]
#13

Hello Bob,
Nice work on that trasformer !

Sincerely Richard
#14

Well now its just getting plain ugly...every wire in this puppy need to be replaced or resleeved. I started doing that and of course to get to one part you have to undo another and another...it will be a miracle if this thing plays after I get done! I've been working on this in between other things and not being as systematic as usual. I needed to take of the first IF transformer can which required removing the push button assembly because the nuts on the top of the can are frozen. Then the nut on the interior of the transformer came off ... yikes...

[Image: https://www.dropbox.com/scl/fi/qdbadn7rd...uag6&raw=1]
#15

I remember working on my 39-6 in 2016. Which is the same radio. Without the preset buttons. Yes, lots of bad wiring. Including inside the transformer. But not too bad otherwise.

People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.




Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
Zenith H725
The PSU filter cap arrived today (thank you USPS!) so I will work on that later. Meanwhile, I have the dial, speaker...EdHolland — 06:42 PM
Philco 610B oscillator wiring
Thanks Terry. After checking my notes I think I recorded about -10v at the 6A7 G4/control grid. The screen grid (G3 &...Tubester — 05:59 PM
The list of my radio & TV collection!
Magical chords of forgotten melodies, old nostalgic music on an old radio... Saturday night blues on the Mid-Waves on an...RadioSvit — 12:20 PM
Philco 42-345 Restoration/Repair
Thank you MrFixr55 the issue with this radio is that the internal coil antenna is missing and there was a wire in its pl...osanders0311 — 11:34 AM
Philco 610B oscillator wiring
Regarding the oscillator circuit which is comprised of the 6A7's cathode, control grid, and screen grid. These elements ...Radioroslyn — 10:33 AM
Philco 42-345 Restoration/Repair
Hi OSanders, First off, welcome to the Philco Phorum where Phine Phamily-Phriendly Pholks Phull of Philco Phacts and P...MrFixr55 — 08:41 AM
Philco 42-345 Restoration/Repair
Today I've been reading through the site trying to learn more about this radio. I also soldered the lose power cord cabl...osanders0311 — 08:24 PM
Philco 610B oscillator wiring
Thanks David! I do have that same later prodution model 610 schematic. I've also studied the Philco service bulletins fo...Tubester — 08:12 PM
Philco 610B oscillator wiring
Some info from Beitmans says late production. David   David — 06:06 PM
Restoring Philco 96
Oh wow! Just found this thread.  Brings me back to early days on this phorum.  I did a 96 back in 2017.  Thread here: ...rfeenstra — 06:05 PM

[-]
Who's Online
There are currently 3187 online users. [Complete List]
» 1 Member(s) | 3186 Guest(s)
Avatar

>