I have a Philco 41-225 that plays fine for the first 10-15 minutes
then the volume seems to get distorted and warbly so to speak.
The tubes all tested good, and the radio seems to have been re-capped
by the previous owner. Where do I look next? Thanks in advance.

Hi Jeff

Check the voltage on Pin #6, grid, of the 35A5. This voltage must be zero. If positive the 35A5 will start to draw too much current and distort. It can be caused by a leaky coulping cap, .01 mfd to pin #2 of 7C6, or a gassy 35A5 tube.

Norm

: I have a Philco 41-225 that plays fine for the first 10-15 minutes
: then the volume seems to get distorted and warbly so to speak.
: The tubes all tested good, and the radio seems to have been re-capped
: by the previous owner. Where do I look next? Thanks in advance.

Norm, I must admit that I am a rookie here, so I need you to tell me where I attach the other lead
of my voltage meter to. Do I just ground the other lead to the chassis?

Hi Jeff

: Check the voltage on Pin #6, grid, of the 35A5. This voltage must be zero. If positive the 35A5 will start to draw too much current and distort. It can be caused by a leaky coulping cap, .01 mfd to pin #2 of 7C6, or a gassy 35A5 tube.

: Norm

:
: : I have a Philco 41-225 that plays fine for the first 10-15 minutes
: : then the volume seems to get distorted and warbly so to speak.
: : The tubes all tested good, and the radio seems to have been re-capped
: : by the previous owner. Where do I look next? Thanks in advance.

Jeff, connect one lead to pin #6 of the 35A5 and the other lead to the negative side of the electrolytic filter caps. Don't use the chassis. On these AC/DC radios the chassis isn't connected to the negative side of the power supply. If you are not sure use pin #7 of the 7C6 as the other connection. It's connected to the negative side of the supply.

Norm

: Norm, I must admit that I am a rookie here, so I need you to tell me where I attach the other lead
: of my voltage meter to. Do I just ground the other lead to the chassis?

:
: Hi Jeff

: : Check the voltage on Pin #6, grid, of the 35A5. This voltage must be zero. If positive the 35A5 will start to draw too much current and distort. It can be caused by a leaky coulping cap, .01 mfd to pin #2 of 7C6, or a gassy 35A5 tube.

: : Norm

: :
: : : I have a Philco 41-225 that plays fine for the first 10-15 minutes
: : : then the volume seems to get distorted and warbly so to speak.
: : : The tubes all tested good, and the radio seems to have been re-capped
: : : by the previous owner. Where do I look next? Thanks in advance.

Hi Jeff,

I agree with Norm, your most likely candidate for trouble is the 35A5. Since your problem begins only after things heat up, it's probably the tube. When distortion begins try watching the tube (in the dark) for signs of overheating .. redness in the plates or hazy colored ionzation (glow).

Use a voltmeter with a high input impediance (not a simple VOM) with negative connected to B- (chassis) and positive to pin #6. Watch for any positive voltage.

Another idea is to subsitute the tube with another, if you have one.

Good Luck,

Phil Sussman
Clayton, Ohio

: Hi Jeff

: Check the voltage on Pin #6, grid, of the 35A5. This voltage must be zero. If positive the 35A5 will start to draw too much current and distort. It can be caused by a leaky coulping cap, .01 mfd to pin #2 of 7C6, or a gassy 35A5 tube.

: Norm

:
: : I have a Philco 41-225 that plays fine for the first 10-15 minutes
: : then the volume seems to get distorted and warbly so to speak.
: : The tubes all tested good, and the radio seems to have been re-capped
: : by the previous owner. Where do I look next? Thanks in advance.

Question for Norm & Phil,

I pulled the radio apart, so how do I know which is pin 6 on the 35A5? I looked for numbers, around the socket, but could not find any.

I guess it shows how much of a rookie I am.

Jeff

Looking at the botton of your tube you will see 8 pins and a keyway that aligns it in the socket. Looking at the bottom, starting at the keyway, counting clockwise is pin #1 all the way around to #8. Hope this makes sense.

Norm

: Question for Norm & Phil,

: I pulled the radio apart, so how do I know which is pin 6 on the 35A5? I looked for numbers, around the socket, but could not find any.

: I guess it shows how much of a rookie I am.

I hope that I did this right. From pin 6 of the 35A5 to the negative side of the cap I measured 35 volts.
It looks like this cap runs from pin 6 of the 35A5 to pin 5 of the 35Z3.

This cap is marked .01K 630V ECI

Did I run the right test?

Jeff

It seems like you did it right but that voltage is a problem. Either the .01 cap is leaky or the 35A5 gassy. Voltage should be zero. You should hear distortion with that high voltage.

The cap should run from pin #6 of the 35A5 to pin #2 on 7C6. It may use the 35Z3 socket for a tie point.

Norm

: I hope that I did this right. From pin 6 of the 35A5 to the negative side of the cap I measured 35 volts.
: It looks like this cap runs from pin 6 of the 35A5 to pin 5 of the 35Z3.

: This cap is marked .01K 630V ECI

: Did I run the right test?

Norm, I checked, and it is using the 35Z3 as a tie point. I think that I will order
a new tube, and a new cap and just do both so I know it is right.

Thank you so much for walking me through this. I'll put another post in here once I get the repair accomplished.

Jeff