[morzh]

Actually a sagging element is not a bad idea at all - warming up and pop may very well be a bad tube that needs to warm up enough to quit.
Could be tested on your tube tester - leave it for approximately the time it takes for the radio to quit and see if the test fails after that.

Start with oputput tube and go back.
Again, "grid touch" test will reveal whether you even have to look at the last two tubes.

[marty]

Hi All;
I will replace the four PF Caps and then do as You all have said and take some Voltage readings and look for foreign matter in and arround the sockets..
I will also do the Grid cap tests and see what shows up..
I will try to take some voltage readings before it goes "pop" as a comparison..
I like that "pop goes the Philco"..
The last time I tried some of my old tubes in my Tube tester, they would not test well in one of the sockets, that particular socket does multiple tube types in one socket, and I suspect it may have gone bad.. But, I can drag it out and see what it shows..
What I have been doing is buying the tubes I need that come pre-tested and use those.. And hope that they are good.. As near as I can tell from the past tubes I have bought, they all seem to be good so far..
THANK YOU Marty

[jerryhawthorne]

Marty, I would do the tests suggested prior to doing the mica caps which are probably good and replacement without exact values could cause alignment problems down the line. Do the grid test suggested and measurements to determine where the problem is. If the radio is totally dead from a sound standpoint, I really doubt your problem is in the area of micas. You did indicate you would like to figure out what is wrong, at this point it is time to do a little trouble shooting. Simple stuff.
Regards, Jerry

[marty]

Hi All;
Jerry, Too late I have already re-placed the two 220PF Caps.. And So Far its is working, but it just went out.. About 3 to 5 minutes..
No signal from touching the Grid caps, But, it just Came back on all by it self, played for a little while then it Squeeled, I switched the Band switch and switched it back the squeeling went away for a little while and now it squeels on both bands.. I have had to turn it off..
There is crackingling while I type and such movement on the kitchen table..
Time for Bed, I will hopefully continue tomorrow night.. When I am fresh I will take voltage readings both before and after..
But, Please, Please give my Your "Input" and suggestions..
THANK YOU Marty

[morzh]

Looks like a bad connection after all. Or a bad tube with some funny stuff going on inside it.
Cleaning the band switch wouldn't hurt either.

[marty]

Hi all;
I have taken Voltages after it goes "POP" and the B+ seems to be fine,
But, I am getting No Filament Voltage.. I don't know If it is a cold Solder Joint or something with the Transformer.. I have not been able to get to the filament voltages on any of the other tubes, as of yet..
THANK YOU Marty

[BrendaAnnD]

Are you checking the filaments on the AC or DC setting of your meter? If the tubes are lighting up, you've got filament voltage.

[marty]

Hi All;
Brenda Ann, Thank You for your reply,, When first turned on Yes, I have filaments and I can see them..
When I checked for Filament voltage after it went POP the chassis was upside down and so I couldn't see the top of the tubes..
I am using a Digital voltage meter and it has automatic selecting for AC or DC.. But, I can re-do it and select it manually just in case..
I plan on adding a few wires for a couple of tubes to check the filaments on each of them, hopfully it will show either they all went dark or just the "42" tube is going dark.. That will answer some of my questions..
THANK YOU marty

[morzh]

the cold solder join theory is becoming stronger.
If there is a bad joint, and the current for filaments is quite large, and it heats up due to a higher resistance and stops conducting....

Just go and wiggle your filament wires, and if all of the filaments go - look no further than where the transformer connects to the very first load.

PS> Just a guess but if that's the case and the radio goes "pop" and then goes out, if you leave it like that for a while it will probably will go back on again. And so it will cycle.
But it may not be a very good thing to do......potentially.

[marty]

Hi All;
Morzh, Thank You for Your reply and it did just that Yesterday, it suddenly came on all by itself, I hadn't touched it at all, it was while I was typing my posting that it came back on, all by itself..
THANK YOU Marty

[jerryhawthorne]

Marty, important to understand if all the filaments go out after the "pop". The rectifier (an 80) is the exception, it has its own supply for the filaments. I hope you examined carefully the two wires that jump from tube to tube and carry the filament voltage. Poke them a little and maybe reheat each connection. It certainly is possible you have a tube with a filament that opens up when hot but that would only kill that tube.
Regards, Jerry

Quick not to Marty, why didn't we think of this before? The radio has a dial lamp, does it work prior to the "pop" and does it go out post pop? Examine the wires going to it, they have been known to deteriorate badly and the case of your radio, neither wire goes to ground.

[marty]

Hi All;
JerryH, Thank You for Your reply.. yes, I knew that the 80 tube has its own 5.0 Volt power supply, which is why I could have B+..
But, I hadn't thought of the possibility of the 42 Tube filament heating up and seperating after some time, which is a secondary possibility after the Cold Joint theory..
Upon re-reading Your post, I have another thought, yes, the Pilot lamp does light.. But, while it is first warming up, the lamp does flicker some.. So maybe there is or maybe a momentary or slight short to ground.. Also just to note, the Center of the Filament transformer does go to Ground..
THANK YOU Marty

[jerryhawthorne]

Yes Marty, I did note that center tap to ground but if was intermittent your filament voltage would have doubled! Not a problem there. I did have a problem on the center tapped type of filament drive on a light bulb with a short to ground, caused wire to smoke. Not a pretty picture until I figured out what was going on.
Probably time to hook a meter to the filament feed and see if it drops off when the radio dies. If not, you have a tube problem with either a dirty connection to the socket or an opening filament.
Jerry

PS: Marty, when it dies try the little finger touch to the volume pot, if you get the happy hum, you will know the problem is not in the last two tubes.

[morzh]

The pilot lamp socket's possible short should be excluded also.
The centertap to GND does not matter, it does not affect the voltage, it is just to keep the buzz out.

[BrendaAnnD]

It's the 'pop' that bothers me. Even if the filament feed is opening up, I would not think it would cause a pop, the sound would simply fade out over a few seconds time. The pop speaks more of a B+ type short. This is what is confusing.

Also, the dial light flickering is not unusual for these old radios. Try removing the lamp and cleaning the base. Make sure the tip is clean and not too flattened. Also, be sure your socket isn't split down the side, this would keep the lamp from making good contact.