Have a odd radio with a common problem. I remember having this problem with another radio but forget the fix. This Philco 90 was working well a few months back. It lost its ground and blew a elect. cap. I replaced the cap and got the ground back. No more caps blowing. The 80 Rect. tube was dead so replaced. Now it powers up and I get all tubes lit. All tubes checked good on tester. I do the old trick of tapping the center tap on the volume pot and I get a audio response back through the speaker. I also get that humming noise when you touch the top of the detect/osliator tubes. So the audio section is working. BUT NO STATIONS. I tried to use my audio modulator to feed a signal into the antenna but as soon as I connected it the radio modulates a local powerful radio station out the speaker. Is this a tuning problem? Obviously using my modulator as a antenna. I am extremely hesatent to mess with the IF tuning. I am leaning towards more the RF antenna tuning. Does anyone have an idea what to do next?
All caps check good along with resistors. Original schematic does not match exactly to this radio. It is a model 90. It has two 47 tubes, 80, three 27 tubes, and three 37/51 tubes. ODD. Has anyone had this problem of a power radio station bleeding through and what does that mean? Thanks for any help. Joe

:Have a odd radio with a common problem. I remember having this problem with another radio but forget the fix. This Philco 90 was working well a few months back. It lost its ground and blew a elect. cap. I replaced the cap and got the ground back. No more caps blowing. The 80 Rect. tube was dead so replaced. Now it powers up and I get all tubes lit. All tubes checked good on tester. I do the old trick of tapping the center tap on the volume pot and I get a audio response back through the speaker. I also get that humming noise when you touch the top of the detect/osliator tubes. So the audio section is working. BUT NO STATIONS. I tried to use my audio modulator to feed a signal into the antenna but as soon as I connected it the radio modulates a local powerful radio station out the speaker. Is this a tuning problem? Obviously using my modulator as a antenna. I am extremely hesatent to mess with the IF tuning. I am leaning towards more the RF antenna tuning. Does anyone have an idea what to do next?
:All caps check good along with resistors. Original schematic does not match exactly to this radio. It is a model 90. It has two 47 tubes, 80, three 27 tubes, and three 37/51 tubes. ODD. Has anyone had this problem of a power radio station bleeding through and what does that mean? Thanks for any help. Joe

The first and easiest thing to check is the local oscillator. The IF of the radio is 175 kHz, so tune a working radio to a quiet space on the dial, and rock the tuner of the Philco back and forth about 175 kHz. below the frequency of the working radio, and you should hear the local oscillator at some point. You will now have a direction to go towards the repair.

Lewis

Very much agree. Probably your oscillator isn't working. Injecting a signal took the place of the non-functional oscillator. Sometimes a strong station will make its way through even with no oscillator, and injecting a signal from your generator will certainly help all of the other stations through.

I don't quite know what you mean by losing ground, or what blew the electrolytics, but strong surges can blow the very thin windings Philco often used on their coils.

T.

Hi

There are several versions of the Philco 90. Although similar output stages are different. Versions have 1 - 47, 2 - 47 and 2 - 45 as output tubes. Schematics for each version are in Beitmans 1926-1938 Radio Diagrams.

Norm

::Have a odd radio with a common problem. I remember having this problem with another radio but forget the fix. This Philco 90 was working well a few months back. It lost its ground and blew a elect. cap. I replaced the cap and got the ground back. No more caps blowing. The 80 Rect. tube was dead so replaced. Now it powers up and I get all tubes lit. All tubes checked good on tester. I do the old trick of tapping the center tap on the volume pot and I get a audio response back through the speaker. I also get that humming noise when you touch the top of the detect/osliator tubes. So the audio section is working. BUT NO STATIONS. I tried to use my audio modulator to feed a signal into the antenna but as soon as I connected it the radio modulates a local powerful radio station out the speaker. Is this a tuning problem? Obviously using my modulator as a antenna. I am extremely hesatent to mess with the IF tuning. I am leaning towards more the RF antenna tuning. Does anyone have an idea what to do next?
::All caps check good along with resistors. Original schematic does not match exactly to this radio. It is a model 90. It has two 47 tubes, 80, three 27 tubes, and three 37/51 tubes. ODD. Has anyone had this problem of a power radio station bleeding through and what does that mean? Thanks for any help. Joe
:
:The first and easiest thing to check is the local oscillator. The IF of the radio is 175 kHz, so tune a working radio to a quiet space on the dial, and rock the tuner of the Philco back and forth about 175 kHz. below the frequency of the working radio, and you should hear the local oscillator at some point. You will now have a direction to go towards the repair.
:
:Lewis

Just wanted to let everyone that helped me with this radio that it is now working. Once I was able to find the correct schematic I identified the correct tubes to use. I used the schematic and used a 24 tube where it said to..the ossilator... and it came to life. Yaaie!! basicallly the ground side of the caps was open. the owner tried to replace and blew the new ones. I found the open ground for the caps and replaced with new caps. He also had the tubes wrong. So thankfully that was the only things wrong with radio and he is happy now. thank you everyone. joe