1939 Philco table radio

[holmesuser01]

I've got a little table radio. It's got rubber insulation on the wiring. When I got it, I replaced all the capacitors without paying attention to the rubber covered wiring. I brought it up slowly on my variac, and was starting to hear AM broadcast noise, when I started hearing the 'putt-putt-putt' noise from the power transformer. I turned it off, and over the next few minutes, with power turned off, the transformer got almost untouchably warm.

What I'm asking is, do you think the transformer is ruined, offhand? I've begun disconnecting it so I can get at the rubber covered wires. When everything is separated, I would like to power it up and be so lucky that it might work.

It smelled hot, but there was never any smoke that I saw. Like I said, AM interstation noise was coming thru the speaker when I heard the noise start. There's a 2 amp fuse on the variac that didnt blow, and I had it running at around 90 volts at the time.

This is one of the radios that used the 6Z4 tube... I think... I'm not looking at it right now... the rectifier looks like the early 6X5GT tube inside.

I appreciate your comments. I hope that this little transformer is more robust than the stuff they make today.

I'll try to post the correct model number as soon as I can get to the radio.

Bruce

[bandersen]

I hope it's still good. I just finished up a 39 Philco and had to replace the rubber wiring too. You can try checking the resistance before powering it up again. Should be something like less than 10 ohms on the primary, a 100+ ohms on the high voltage secondary and less than 10 ohms on the filament secondary.

[dieseljeep]

You might have got lucky and didn't destroy the transformer. When you disassemble the transformer and insulate the leads, energize the primary, bringing it up slowly on the variac. If it runs cool, it should be OK.
The 84/6Z4 tube is identical to the 6X5G, except for the base. See Bob Anderson's postings to see a picture of the newer issue 84/6Z4.

[DavGoodlin]

I have a Zenith 6S656 that came to me with a shorted 6X5 and fried transformer that popped like that. I was not lucky because mine did heat up after re-capping the set. Luckily I found a found a trans with 6.3 volts and 500 VCT in a junky tuner in my heap. I did not need the separate 5 volt winding and, of course its fused now!

A question about tubes: My Philco 42-1009 needs a 5Y4 tube. I have some 5Y3's, and it looks like i can use one if pins 7/2 3/4 and 5/6 are swapped around. Does anybody know why there are rare tubes like the 5Y4 that are simply variations of popular types???

[dieseljeep]

Originally Posted by DavGoodlin

I have a Zenith 6S656 that came to me with a shorted 6X5 and fried transformer that popped like that. I was not lucky because mine did heat up after re-capping the set. Luckily I found a found a trans with 6.3 volts and 500 VCT in a junky tuner in my heap. I did not need the separate 5 volt winding and, of course its fused now!

A question about tubes: My Philco 42-1009 needs a 5Y4 tube. I have some 5Y3's, and it looks like i can use one if pins 7/2 3/4 and 5/6 are swapped around. Does anybody know why there are rare tubes like the 5Y4 that are simply variations of popular types???

It's kind of hard to figure out what the manufactures and engineers were thinking about when they do that. My Philco 37-116 uses a 5U4, where my 38-116 uses a 5X4. The only difference is the pin-out.
Zenith used a tube socket that didn't have the contacts for a 5Y3. Maybe your Philco does. If so, rewire it.

[DavGoodlin]

Originally Posted by dieseljeep

It's kind of hard to figure out what the manufactures and engineers were thinking about when they do that. My Philco 37-116 uses a 5U4, where my 38-116 uses a 5X4. The only difference is the pin-out.
Zenith used a tube socket that didn't have the contacts for a 5Y3. Maybe your Philco does. If so, rewire it.

Thanks for the green light on that. I did not want to commit some conservation nono, but I will prominently (not permanently) label the change on the chassis.

I can only guess that manufacturers ran out of the popular tubes and that held up production.
A quick fix was to get something-anything to work instead so that set could ship. I have models 501X, 118X, 20, 89, 42-1009, 42-380 all close in age but have different tubes

Reading Ron Ramirez's Philco (1928-1942) excellent book sure helped me to understand how driven that particular manufacturer was to get their product to market.