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My Next Project: Log Cabin - Printable Version

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My Next Project: Log Cabin - Winky Dink - 12-12-2015

This week I finished up a few projects and then said, “What’s next?”  I  checked Craig’s List and there it was:  “My grandfather’s 1942 Philco radio, $50.”  This was perfect for me.  It was so beat-up that I didn’t have to fret about the patina, but all the parts were there--all the knobs, all the buttons.  I identified it in the Philcoradio gallery.  It’s a 41-250.  From the Craigslist photo I could tell that the escutcheon was hopelessly broken, but also found that good reproductions were available.  


So, I brought the set home.  Now my room is filled with that alluring aroma--that delicate musty scent that says, “I’ve been the attic for 50 years.”  I’ve ordered the documentation from Chuck, I’m ordering an escutcheon from Antique Knobs, and I’ve ordered the one tube that I’ll need.

This will keep me busy for several months.  I’d post a photo, but it looks just like the other 25,000 “log cabins.”

When I cleaned up the tubes, I totally erased the markings on a good XXL.  I’ve done this with all-glass tubes and I wanted to try glass-etching on a tube, so I tried it out here (I know it’s not necessary for a tube with Bakelite or metal base, but it can be useful for all-glass tubes).  It takes 5 or 10 minutes to do a neat etching.  For what it’s worth, here’s my process:
 
https://goo.gl/photos/DoduRLPhnA3kkVNc7

One question about the 41-250--does it have a back?  It doesn’t look like it had a back, but I thought I saw someone selling reproduction backs for this model.

RE: My Next Project: Log Cabin - 462ron - 12-13-2015

I have the same set, it was my first ever Philco. It plays pretty decent and is a good sensitive unit. Mine has no back and don't see any signs that it ever did.

Ron

RE: My Next Project: Log Cabin - Winky Dink - 12-13-2015

I saw the reproduction back again--it was for a different, newer Philco model.

I knew there was a small hole in the speaker cone. When I removed the speaker to see what repair was needed I found a huge (2"X2") hole that wasn't visible from the outside. I should have anticipated that from the way the grille cloth was torn. I'm a slow learner.

RE: My Next Project: Log Cabin - mikethedruid - 12-14-2015

Re-coning is not that awfully difficult, I found. Take a look at my thread on electronic restoration of my 37-61. I had a badly torn cone, but good voice and field coils and spider, so I rebuilt it myself. I give a link to a YouTube video that has the procedure I pretty much used. If you don't feel as adventurous as I was, you can find several folks who will rebuild them among Ron's links here. Good luck !

RE: My Next Project: Log Cabin - Winky Dink - 01-11-2016

When I started this I swore that this time I was just going to work towards a sound electronic restoration--no fussing with chassis cosmetics or esthetics--and that it wasn’t worthwhile to disassemble the upper chassis parts.  Yet here I am, cleaning the imprint on a transformer and removing the unsightly old rosin.

[Image: https://lh3.googleusercontent.com/-sSGRMLq-rjI/VpOqtQ8wZmI/AAAAAAAAQWk/Fi5kI06YA8s/s400-Ic42/41-250%252520206.jpg]

And I thought that nobody would notice a few rust spots, but I ended up doing this:

[Image: https://lh3.googleusercontent.com/-64zjZ1nQWvo/VpGQPkZTAAI/AAAAAAAAQTw/C4IINBseIZM/s520-Ic42/41-250%252520322.jpg]

This is not a particularly interesting restoration.  Mine looks just like everyone else’s restoration.

[Image: https://lh3.googleusercontent.com/-beX13twgO_0/VpGQRWmBO6I/AAAAAAAAQUA/C2RriNmHDCg/s800-Ic42/41-250%252520329.jpg]

When I got this far, I reviewed the extensive 41-255 restoration thread on Antiqueradio.com…
http://antiqueradios.com/forums/viewtopic.php?f=6&t=152169&sid=4666b2d9379c51d2077de628a820a5b4&start=340
…and found that I had, indeed made at least one error.  I hadn’t noticed that a capacitor to the tone control was 1000 volt-rated.  I retrieved the old condenser to verify.  It was, indeed, a 1000 volt cap.

[Image: https://lh3.googleusercontent.com/-tskA_IrjaAc/VpOt8niHyoI/AAAAAAAAQW4/dvgzTkOA3VQ/s320-Ic42/41-250%252520617.JPG]

I couldn’t find a .003-ohm cap to replace it (that must be one of Philco's "special" condensers), so I used a normal .003 uF cap instead (and I also healed the burn scar on the wire).

 [Image: https://lh3.googleusercontent.com/-FNCgrWi6h9g/VpGQUDxQ69I/AAAAAAAAQUY/NrZXIpM6go4/s400-Ic42/41-250%252520617.jpg]

The picture below shows my process when starting a restoration:
-Test all components that need testing.  
-Mark those that need replacement with a red dot, those that are OK with a green dot, and the ones that need to     be retested (like resistors that have to taken out of the circuit) with a yellow dot.  Paper caps don't need dots.
-Desolder and disassemble each connection to components and wires that will be replaced and reattach the original wires and leads without soldering.  
-On each tube socket, I mark the #1 pin with a red dot.

[Image: https://lh3.googleusercontent.com/-pBozasKa8ho/VpGQTc2HSMI/AAAAAAAAQUQ/Wo0_26l8XnE/s500-Ic42/41-250%252520371.jpg]

I have a question about the pilot lamp bulbs.
The dial lamp, 34-2210, with the blackened end:  Is it frosted and does it have the peculiar horizontal filament (like the shadow meter)?  And the button-indicator lamp, 34-2064 is frosted, but does it also have the horizontal filament?  I’ve looked at all the bulbs from the set, and most may be replacements, but the filaments all have the same arc--even the one with the blackened tip.

RE: My Next Project: Log Cabin - codefox1 - 01-14-2016

Lots of pilot bulbs get blackened tips and "silvery" deposits after years of service, frosted or not.

RE: My Next Project: Log Cabin - Winky Dink - 01-15-2016

Thanks. I'm pretty sure that the original dial lamp was painted black on the tip and frosted. I've seen photos and several references to this bulb. I suppose this was done to diffuse the light evenly across the dial rather than have a glaring spot in the middle. I remember reading some reference to the bulbs having horizontal filaments, which I guess would be for the same reason they were used in the shadow meters.

I can etch the bulb for frosting and use high-heat paint for the tip, but I don't know if anyone sells bulbs with horizontal filaments.

RE: My Next Project: Log Cabin - Winky Dink - 01-16-2016

Regarding my bulb question:

(1)  I had the part numbers from the service documentation.
(2)  I visited “parts values” on the Philco Repair Bench.
(3)  The answer is:

[Image: https://lh3.googleusercontent.com/-399d7MoY6TA/VpnRL5qqckI/AAAAAAAAQXU/8mvOmjVfrqs/s400-Ic42/41-250%252520790.jpg]

Since the “special flat filament” bulb is not available, I made a reproduction:

[Image: https://lh3.googleusercontent.com/-6TfVkEIracc/VprLXk0ekSI/AAAAAAAAQXk/fFnszGJyYbA/s500-Ic42/41-250%252520791.JPG]

The only high-temperature paint I had was “wrinkle coat,” which doesn’t cover well with a thin coat.  Flat black automotive or barbeque grill high-temperature paint will work better.

RE: My Next Project: Log Cabin - Winky Dink - 01-28-2016

I’m stymied.  After getting good voltage readings and rechecking every circuit and component multiple times, I get no audio.  No noise, no hum.  The only thing from the speaker is a click when changing the band switch.


I expect that there’s something obvious that I’m overlooking, and I hope someone can point me in right direction.  Here’s the schematic with data (use the link, then click the photo to enlarge).
[Image: https://lh3.googleusercontent.com/-UI1OHjscqlU/Vqf9Sxz6sxI/AAAAAAAAQYY/VkR2Z822kEw/s200-Ic42/41-250%252520812.jpg]
https://goo.gl/photos/mJxdusADGP7eqDY37

In the meantime, I’ll consult Elements of Radio Servicing to see if I can figure something out.

It looks pretty good, but I’ve been unsuccessfully looking for escutcheon reproduction since December.
Here are some photos of the chassis:

[Image: https://lh3.googleusercontent.com/-UwIKWFq9Eb8/Vqf9UQ_BdQI/AAAAAAAAQYg/nQ2bn9OQlCY/s200-Ic42/41-250%252520803.jpg]
https://goo.gl/photos/U6E1MUKAg8n8UL6L6

[Image: https://lh3.googleusercontent.com/-nchnekH9oRs/VqlP5oG0oHI/AAAAAAAAQaM/QEqaNosnOlI/s200-Ic42/41-250%252520853.jpg]
https://goo.gl/photos/T6m2qh9iuYD7Kj158


[Image: https://lh3.googleusercontent.com/-hDEYDvGlECY/Vqhc2dTIHmI/AAAAAAAAQZg/WILidrGqRrw/s200-Ic42/41-250%252520852.jpg]
https://goo.gl/photos/TtmKHDvvHx4QpFU89

RE: My Next Project: Log Cabin - mikethedruid - 01-28-2016

Time to start signal tracing with an audio signal source. I'd start at the intersection of C52 and R50. If you hear the signal loud and clear you can go back farther, I'm sure you know the drill.

RE: My Next Project: Log Cabin - Winky Dink - 01-28-2016

Unfortunately, I don't know the drill. I actually have a signal tracer, but don't really know how to use it (even with the instructions). I tried to use it a couple of days ago and couldn't find a signal anywhere, but that was like a blind man trying to hit a pinata.

Now, with some idea of where to start looking, I'll read the instructions and try again. Thanks.

RE: My Next Project: Log Cabin - Winky Dink - 01-29-2016

So...I start experimenting with the signal tracer, and after a while I can tune in the signal from the signal generator at C52/R50 which is the grid of one of the 41's. Before I moved to another signal point, I hooked up the loop antenna and found that I could tune in the strongest local station, audible through the signal tracer only (I turned the tracer speaker off to be sure there was no audio through the radio speaker)...and the audio was moderated with the radio volume control. Then, for reasons unknown, the sound of the audio seemed different. I turned off the signal tracer, and realized the audio is through the radio speaker. Go figure.

Now I can tune in the local stations very weakly, each over a broad range-- and I'll move on to alignment.
Thanks again Mike. You are credited with an assist.

RE: My Next Project: Log Cabin - mikethedruid - 01-29-2016

Icon_thumbup Good to hear ! That's how we learn the best, by doing. I'd look for any bad solder joints in the audio section before you go on any further. I use a magnifying glass. Poke around too to just make sure. I'd use a plastic straw or a wood chopstick, something insulated and non-conducting. If all is well, go on to the alignment. Seems you're doing fine.

RE: My Next Project: Log Cabin - Arran - 01-29-2016

 Check for an open primary winding on the output transformer, which looks like an original one judging by your under chassis shots, it's a common failure point on the 1940-42 Philcos unfortunately.
Regards
Arran

RE: My Next Project: Log Cabin - TV MAN - 01-29-2016

Since your radio uses loctal tubes, you might want to check this before you get in too deep. http://www.philcoradio.com/tech/hum.htm  Been there, done that on a Zenith. Ditto on the output transformer. One side of the primary could be open. Had that before. In my case, the output was distorted and low. Can check for continuity or voltage on the plates on the output tubes.