[tfonzart]

This is all so helpful, thank you all for the detailed comments and advice.

MrFixr-that's a story that will stay with me.

As suggested, I'm not doing anything else until I finish replacing all caps.
I'm a little over half-way through. Also, fixing a number of cracked wires and anything else I find along the way.

[MrFixr55]

There were a series of rectifier tubes, starting with the 84 / 6Z4 7Y4 and 7Z4 that were designed for Auto radio use where the potential voltage differential between the cathode and heater, by the nature of being supplied by the Auto's 6 Volt electrical system, is essentially equal to the DC output of the rectifier. The max cathode vs heater potential difference is 450V, comfortably higher than the 180V B+ voltage used by Philco in most car and home radios where this tube is used. Newer versions of this tube include the 6X5 and 6X4 which have a somewhat lower max cathode / heater differential of 350V. (The voltage was 450V in the RC15 (1948) version but seems to be specified differently in subsequent versions such as theRC25 (1963?). It became popular to use these tubes in AC powered (home) sets as well as low to medium power HiFi amplifiers and preamplifiers, eliminating the need for a separate winding for the rectifier filamentary cathode which by nature, that winding is also above ground potential by the raw B+ output of the rectifier circuit. So, do we have the differential in the tube or in the transformer?

[Arran]

From what I can tell this series of Philco models with this chassis were not especially prone to transformer failures, I think that Philco was aware of the tolerances of these tubes, based on their experiences with car radios, and (unlike some of their competitors) respected them. In addition to keeping the maximum voltages and currents low by using #41 or 6K6 tubes for power outputs, most of the other tubes were loctals that used 150 milliamp heaters. One thing that these sets are known for is failed audio output transformers, I'm not really sure why but many have even vintage replacements in them.
Regards
Arran

[MrFixr55]

Right on, Arran. My 41-250 has a vintage replacement OPT. Most of the Philco sets using the 84 / 6X4 / 7Y4 had 180V B+ and even in Push Pull, 41s and 6K6s had a rather low output wattage at that voltage.

[tfonzart]

All Caps Replaced!
Fixed a number of cracked wires along the way.

With all the tubes in, fired up (slowly) and DC voltages looked good.

Tried the various bands and tuned across the range, but no stations pick-up. Can hear some faint noise through the speaker, but that's it for now.

[RodB]

Sounds like the oscillator isn't running. If you can send a modulated IF signal through the antenna and hear audio then the oscillator isn't running.

[MrFixr55]

Hi TFonzart,

Divide and conquer. Add an aux input by breaking the connection between cap#38, resistor #39 and the output of the 2nd IF transformer. Connect cap#38 to the common of an SPDT switch, one leg to the junction of resistor #39 and the output of the IF transformer and the other leg to an RCA jack tip. Ground the body of the jack to the chassis. Inject an audio signal here. If sound, troubleshoot the rest of the set. If no sound, troubleshoot the audio and power supply section. In addition, direct injection of "old time radio" from an MP3, computer or CD player will make better sound than receiving AM.

When troubleshooting, make sure that if your set has push buttons, that the one for manual tuning is pushed in and is clean, and wired correctly. None of the bands will work if the push button for manual tuning is not pressed in and connection made.

Also wiggle the tubes, clean the socket contacts and tube pins and try to tighten the contacts. I have not yet experienced this, but many antique radio folks have run into trouble with loctal pins and sockets.

If you do not have test equipment, take a transistor radio, tune in a station above 1,000KHz, hold it up to the oscillator coil and tune the radio in question across the band. If you hear squeals or the transistor radio grows silent as the dial scale indicates a station about 460 KHZ below what the transistor radio is set to, then the oscillator is working.

Hope this helps.

[tfonzart]

MrFixr

This is really helpful. I didn't know about the pushbutton issue. When I choose one of the buttons, I actually heard a new program through the speaker - woohoo!. Now I have to figure out what the rest of the buttons do and find the manually tuning button.

[tfonzart]

Okay - I feel like an idiot. That was a simple fix! The right button is the manual button.
Tuner works, have stations now!

You all are so helpful - thanks so much! Saved me hours of trying to figure out what was wrong - turns out, it was just pushing a button!

[radiorich]

Hello tfonzart ,
Don't Be hard on yourself we have all been there at one time or another glad it is working .

Sincerely Richard

[morzh]

>>I feel like an idiot

The key word is "like."

[tfonzart]

Thanks Richard and Mike!

[tfonzart]

Question about the glass faceplate over the tuner dial.

When I removed this, it was held in place by a metal bracket and some type of gasket between the metal bracket and the glass. But that had dried and cracked, disintegrating as soon as it was removed.

Ideas for what to use when for this when reassembling?

Also, my new push buttons have a poor interference fit, I was thinking of using something like clear nail polish maybe to create some friction between the metal post and the push button so they don't fly off. What do you all use for this?

Thanks!

[morzh]

Nail polish might damage the button if it is a clear plastic (not backelite) due to some acetone being the solvent in it (unless it is not).
The film it forms will not last long if you keep pressing it: it is not a glue and will crack, and the cap will fly off again.

I would suggest a threadlocker, like Loctite.
You could also use shims.

The advantage of threadlocker it will hold things in place, but it is not a glue and so if you ever need this cap off, it will come off, even if not without effort. With glue it might take too much effort and then you might damage the cap.

[RodB]

If the shaft is flat and has a slit then the two "fingers" could be slightly displaced but you can't bend them very much without breaking one. Maybe try some paper or gum wrapper shim like the old days.

Maybe try using a sheet of felt and trace the outline of the dial cover.