Neophyte restorer here,
I found this thread through a Google search for information regarding my grandfather's model 20.
I've had good luck retubing it and conservatively restoring the cosmetics. The lamp holder assembly was there at one point but had been badly damaged and had to be removed. It never worked, at least with any bulb I tried in it.
It is an earlier model and it has the translucent white dial material.
I could really benefit from (and I'd REALLY appreciate) a step-by-step guide on how to add this dial lamp back were I to find a replacement. TIA...
Got a witness, Ron! My model 20 plain front does have a dial lamp. A parts chassis that I purchased at a previous MARC event has one as well. Take care and BE HEALTHY! Gary
I found a dial lamp and I've mounted it.
I thought I might've been able to tell where the original connections would be made, but honestly I can't and I don't see anything helpful on the schematic.
Could I get someone to PLEASE tell me how to wire in this lamp assembly?
I think I've read somewhere that it connects to one (or two?) of the 27 tube pin socket(s). But I don't know which one (or two).
Or is one to the chassis ground and the other to one of the tube pin sockets?
If it sounds like I'm not experienced with tube radios, you'd be exactly correct.
Lil' help here...please!
Thanks!
Update: Since I had the radio chassis out of the cabinet I decided to do a better job of cleaning it up than I did when it was given to me as a kid.
I used an air compressor to blow out some detritus that I'd missed the first time and when I powered the radio up to listen to it while I waited for some helpful posts from the experts here, it has developed an arc in that paper wound transformer. I can see burns in the paper. I presume this is very bad news. Advice is appreciated...thx...
It would connect to pin one and pin five of the closest 5 pin tube to the lamp. The lamp socket can not be grounded to the chassis. Must have two connections. Neither connected to it's mounting bracket.
Pins 1 and 5 are closer together than the others. The 27 and 24A share the same base configuration.
http://www.nj7p.info/Tubes/SQL/Tube_query.php?Type=27
Thanks, that's exactly what I'll need to complete the lamp install. I'll DL it for future reference.
In the meantime, this (secondary?) transformer (only two output taps, number 4231J stamped on the bottom) appears to have eaten itself.
It's not dead shorted yet. It's had less than five seconds of current applied to it since I discovered its new "fault". It worked fine before. Next, I tried a
"nothing to lose" last-ditch option of applying Wood Glue to it and letting run down into the paper hoping it might insulate the windings, but I was aware
it had less than a 10% chance of working and ultimately it didn't. It quieted the arcing, but effectively it's closing the metaphorical barn door after the racing thoroughbred "Magic Smoke" escapes. I'm looking for one of those transformers now. If someone has one available that they're willing to part with (or better yet, if they know of a modern equivalent-it appears to me to be fairly straightforward, I just don't know the specs for it) I could really use some help.
Thanks again, and best to everyone...
That's the filter choke in the power supply #28. Have the caps inside the metal can on top of the chassis been replaced w/film caps? If not this can cause that choke some thermal discomfort.
I would suspect that choke should measure several hundred ohms but it does have that a cap in parallel with it. Cap could be shorted. If it's arcing back to the core you could try insulating it from the chassis.
https://philcoradio.com/library/images/schem/20a.jpg
Yes, you're right, it's the amplifier filter choke. Sorry for the confusion.
I think that its physical decomposition may have been exacerbated when I blew some dirt out of the chassis.
I also have a dim recollection of having noticed it when I fired it up (and did a less thorough cleaning of it) in my younger days
back when I first acquired it.
I'm looking for a replacement. If anybody knows of one or has one, that'd be the next thing on the agenda to fix.
Also, (I hate to ask, I know that everyone here knows a LOT more about this radio than I do) if someone could please post a photo of the lamp connection points to the tube sockets, I'd really appreciate it. I've read that it taps the filament pins on tube #27 and I I have the leads run right to it-I just don't want to make a "dumb"
mistake. I believe I have some #43 lamps on hand. Will that bulb work? Or do I have to have #40's? I've also read that #13 bulbs will work as well.
I've worked on a few tubed amplifiers over the years, mostly just retubing hi-fi and a couple of guitar amps and then adjusting their bias. My discomfort level with this older gear is higher and this one's a "keepsake". Thanks to everyone who's taken the time to help.
Methinks your looking for a #41 lamp 2.5v@.5a if it's a screw in type 43 if bayonet.
> I've read that it taps the filament pins on tube #27 and I have the leads run right to it-I just don't want to make a "dumb"
The simple answer to your dilemma is to remove the #80 tube. Look at the 5 pin socket (27 tube) and find the two closest pins that are together. Use you voltmeter and measure the ac voltage there. If you've got the right ones it will have 2.5v. Proceed solder wires.
Thank you, Terry!
That I believe I can do!
Back to the filter choke:
I've found one and it's on its way (slow boat) but the ad I saw for it said that it measured 438 Ohms.
I wouldn't be worried about that spec-except later I found a Philco chart that lists the 4231 filter choke as being 4000 ohms and 80mA.
I guess I can just drop it in and hope, but...well...should I trust the chart or the guy selling the choke?
Did the Philco chart add a zero, maybe?
Thanks again...
Update:
First, thanks again to everyone who's contributed. I know that I know just enough to know how much I DON'T know, especially when it comes to vintage tube (radio) conventional wisdom.
The Filter Choke transformer's here and in. The radio is functioning well. I've realigned it (it wasn't very much out of alignment in the first place but I couldn't know that until I checked it) and I've installed the light and I've checked it with the 43 bulb I had (way too dim) and the 41 bulbs should be here today.
There is some residual hum (no surprise there from what I've read elsewhere by many of the experts here in other threads) but it's not really that bad considering it's a 90-year-old radio. I think it's actually slightly lower in volume than before. I think that filter choke had begun exhibiting minor misbehavior many years ago and I'd just forgotten about it. I presume the filter cap(s) might be to blame, but I'm not sure if I'll undertake changing them right away.
Quick question: Has anyone ever tried LEDs in the lamp?
I can think of good reasons to try it (brightness and decreasing the load on the 27 tube) and good reasons not to try it (LED's are noisy, especially in MW/AM).
Is there a consensus one way or another?
Thanks again to all...
The 41 bulb is here and in. Perfect.
It picks up 7 stations clearly without breathing hard, so I think as soon as a new bakelite (with insulated face) plug arrives, I'm done.
It still has a bit of trouble remembering the lyrics when it's not on a station, but it's not intrusive.
I'll keep my eye out for other radios to rescue. I read this forum often. I know this is a Philco-specific forum so I won't bring up my last-gen ZTO. ; - )
Thanks to all...
Actually, RTM, although this is the PHILCO Phorum, we DO talk about other radios. If you go to the main page of the site
Philco Phorum Index and scroll down, you will find a section called "Various And Sundry Categories." In it you will find sections for "
Other Radios ( Non - Philco ) ", "
Test Equipment ", and "
Vintage Hi-Fi, Stereo, and Audio ". These are the sections where we talk about our restorations of other companies' radios, discuss test equipment old and new, and all kinds of audio gear, old and new. You'll find this is a very diverse place, with a lot of fun for everybody. You will also find that many of us have been working on many different brands of radio for YEARS, (in my case well over half a century) and are very willing to help the best we can with out knowledge of any brand. Presently I'm working on a Crosley 716 from 1936. You'll find my thread about it in the "Other Radios" section.
Thank you for pointing that out, Mike!
I'm headed that way. I'm having a few problems realigning the SW section of the aforementioned last-gen 7000-2.
It receives...pretty well...but is by far the least sensitive SW rig I own. Of course, there's the issue of finding interesting things to listen to besides setting my clocks to the second (if I'm lucky) twice a year. Thanks for the heads up!