I am presently working on a Philco 47-204. It worked, then something popped near the osc. and now the pilot goes bright and stations fade away. Next step seems to be a blow-up.
I can't read the schematic and was wondering if someone had a ledgible one. Not my radio, so I don't want to invest too much time nor money. Any help would be appreciated. Thanks.

Hi Cindy

Schematic isn't the best but mostly readable:

http://www.nostalgiaair.org/PagesByModel/607/M0013607.pdf

Lamp is across a section of filament of the 35Y4 tube. Check continuity of filament with an ohm meter between pin #1 and #8. May be open?

Electrolytic filter caps should be replaced if they haven't been already. Caps dry out and can short over time. This could cause the pop you heard?

Norm

:I am presently working on a Philco 47-204. It worked, then something popped near the osc. and now the pilot goes bright and stations fade away. Next step seems to be a blow-up.
:I can't read the schematic and was wondering if someone had a ledgible one. Not my radio, so I don't want to invest too much time nor money. Any help would be appreciated. Thanks.
:

Current does flow through to dial light. A bright dial light would indicate the is a short in the B+ line. Filter capacitors are likely the problem. Replace them. You should replace all of the wax and paper capacitors too. They will all be leaky.

:Current does flow through to dial light. A bright dial light would indicate the is a short in the B+ line. Filter capacitors are likely the problem. Replace them. You should replace all of the wax and paper capacitors too. They will all be leaky.
:
I did replace all the caps, radio was playing fine first time. Later turned it on and the pop seemed to be coming from the side of the tuner, next to the 35Y4 tube. I have no way to test the tube. But I will check the filaments. I don't have a replacement tube either.
Problem is: Guy who owns the radio, he played it till it HUMMED loudly. I have no idea all he had burned up. I am afraid to try to check the voltage as I know it is going to blow something again. Nightmare....

::Current does flow through to dial light. A bright dial light would indicate the is a short in the B+ line. Filter capacitors are likely the problem. Replace them. You should replace all of the wax and paper capacitors too. They will all be leaky.
::
:I did replace all the caps, radio was playing fine first time. Later turned it on and the pop seemed to be coming from the side of the tuner, next to the 35Y4 tube. I have no way to test the tube. But I will check the filaments. I don't have a replacement tube either.
:Problem is: Guy who owns the radio, he played it till it HUMMED loudly. I have no idea all he had burned up. I am afraid to try to check the voltage as I know it is going to blow something again. Nightmare....
:
Make your meter connections to the B+ while the radio is off, then power it up slowly with a variac and observe the voltage/current draw. If the B+ is ok, you can then make other voltage checks.

Hum is an indication electrolytic filter caps need to be replaced.

Norm

:::Current does flow through to dial light. A bright dial light would indicate the is a short in the B+ line. Filter capacitors are likely the problem. Replace them. You should replace all of the wax and paper capacitors too. They will all be leaky.
:::
::I did replace all the caps, radio was playing fine first time. Later turned it on and the pop seemed to be coming from the side of the tuner, next to the 35Y4 tube. I have no way to test the tube. But I will check the filaments. I don't have a replacement tube either.
::Problem is: Guy who owns the radio, he played it till it HUMMED loudly. I have no idea all he had burned up. I am afraid to try to check the voltage as I know it is going to blow something again. Nightmare....
::
:Make your meter connections to the B+ while the radio is off, then power it up slowly with a variac and observe the voltage/current draw. If the B+ is ok, you can then make other voltage checks.
:

In lieu of a variac, can construct a dim bulb tester. A light bulb in series with the hot side of a short extension cord. Will help protect while testing.

Clifton

:::Current does flow through to dial light. A bright dial light would indicate the is a short in the B+ line. Filter capacitors are likely the problem. Replace them. You should replace all of the wax and paper capacitors too. They will all be leaky.
:::
::I did replace all the caps, radio was playing fine first time. Later turned it on and the pop seemed to be coming from the side of the tuner, next to the 35Y4 tube. I have no way to test the tube. But I will check the filaments. I don't have a replacement tube either.
::Problem is: Guy who owns the radio, he played it till it HUMMED loudly. I have no idea all he had burned up. I am afraid to try to check the voltage as I know it is going to blow something again. Nightmare....
::
:Make your meter connections to the B+ while the radio is off, then power it up slowly with a variac and observe the voltage/current draw. If the B+ is ok, you can then make other voltage checks.
:

"(SNIP)....Problem is: Guy who owns the radio, he played it till it HUMMED loudly. I have no idea all he had burned up. I am afraid to try to check the voltage as I know it is going to blow something again. Nightmare...."
:

On this set, the only thing that could get damaged by a shorted filter cap is the rectifier tube (due to current overload). If the set has a resistor between the rectifier cathode and the first filter cap, that would probably "smoke" first.

However...

The sound effect that you described sounds like an electolytic cap boiling and popping its case. Tubes
don't make noise when something inside fails.

So, you might want to check your recap work, just in case you installed a polarized cap backwards (all too easy to do if you are replacing chassis-mounted canned caps with tubular ones). In a set with multiple filter caps, it would probably work for a while, until the reversed cap catastophically failed.

:"(SNIP)....Problem is: Guy who owns the radio, he played it till it HUMMED loudly. I have no idea all he had burned up. I am afraid to try to check the voltage as I know it is going to blow something again. Nightmare...."
::
:
:On this set, the only thing that could get damaged by a shorted filter cap is the rectifier tube (due to current overload). If the set has a resistor between the rectifier cathode and the first filter cap, that would probably "smoke" first.
:
:However...
:
:The sound effect that you described sounds like an electolytic cap boiling and popping its case. Tubes
:don't make noise when something inside fails.
:
:So, you might want to check your recap work, just in case you installed a polarized cap backwards (all too easy to do if you are replacing chassis-mounted canned caps with tubular ones). In a set with multiple filter caps, it would probably work for a while, until the reversed cap catastophically failed.
:
Problem apparently was an OLD cap that was not on schematic going from the 50L6 to 14a?. I thought it was a resistor. I removed it and tested with my dim bulb tester, yes I have one. Bulb went dim...so I tried the radio, worked great. Glad I did not burn up rectifier tube, I have no replacement. Radio plays great now. Thanks for the help.