Hello, I have a 48-1262 that I just recaped, it did not work when I first got it. I completely recaped all the paper capacitors and the electroylics, with the same value. I had to go to a slightly higher mfd in the electrolic caps, but within 20% of value. I have checked the tubes and they are good. I powered it up and no pops or smoking...good so far. I get sound from the speaker, but I can not pick up any stations. I have tried all diffrent antenna variations including the original hook-up...I only get a squealing noise when I hit where a station should be. There is no loud hum or noise in between stations. I have other radios and they get recption no problem, so I know it is not the radio location. What do I do now? I double checked the caps against the schematic and they are correct, I also have a spare chassis that is non-working and all the connections line-up as should be. The only thing that I changed is there were two caps that had a coil wire trap wraped around them and according to the philco service tip the 37A they can be eliminated with no effect. These were I-F bypass capacitors.
Thanks
David
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Check all the loop antenna and OSC coils for continuity. Also the two IF transformers as well for open windings. Also check the resistor/cap Rf filter in the second IF can. R304 may be open or way high in value.
What do you mean by OSC coils? Also the cap that you were refering to was a 75mf and I replaced it with a 100mf.
Posts: 1,703
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Oscillator, abbreviated to OSC. It's L400 on the schematic.
I was referring to the resistor R303 in the IF transformer.
Everything seems fine. I am wondering if it is the antenna. I do not have the original antenna, but I have the cardboard that it was attached to. Do you know hom many loops were used on this radio. I think that with out the pproper antenna the radio will not work properly. I am also still wondering about those capacitors tha had the coils on them.
Thanks
David
Posts: 1,703
Threads: 55
Joined: Sep 2005
City: Evanston, IL
The original Philco service bulletins never gave the number of turns for coils and loop antennas. You may have to find a correct one from a "junker set." Also advertise to anyone who may also have this model to count the turns for you on their set.
The special IF bypass caps may not be the problem, but if the originals are NOT leaky, leaving them in for now won't hurt.
When replacing parts and wiring maybe you disturbed or re-routed parts or wires causing this IF feedback? Lead dress can be critical sometimes.
A missing loop antenna, whicis also the MAIN antenna tuning coil for the set may casue this. The AVC voltage routes through the loop to the grid of the first tube. If missing it could also cause havoc.
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