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Just finished up a Philco 38-12. put in a power supply transformer, new rectifier tube, recapped it and replaced a resistor. this radio had a phono plug added to it.
just picked up a Philco 40 145T and a Philco 46 1203 Radio and phono combo.
working on the Philco 40 145T and it appears it needs a replacement output transformer 32-8603. Does anyone have one?
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City: New Hampshire
isolated the wires on the primary output transformer. I was able to measure 700 ohms on the primary and without the secondary completely isolated I measured one ohm on the secondary. Shrunk tube the primary white wire that was badly melted and turned on the radio. The speaker works but it has a lot of static. The volume control works I connected up the AM loop antennae. radio doesn't seem too pick up any station I haven't heard any type of music or talking other than like static out of the speaker. I cleaned up the frequency band switch and removed all tubes and cleaned all connections on the tubes.
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Have you done a complete recap? Most of the time that will fix problems like this, and even if it doesn't, you have to do it anyway. A good many of the paper caps are bound to be bad, and a few of the resistors, too.
Oh, yeah, and you have rubber coated wire all through your radio. Very likely much of it has turned brittle, cracked, and fell off the wires, leaving them bare. They really oughta be replaced or sleeved before putting power to it.
Tubes OK? If you don't have a tube tester at least test the continuity across the heater pins. It's probably not worth it to test for shorts manually, but keep it in mind for later.
I think given the symptoms I'd try to see if your oscillator is working. It's a pretty easy test.
Static from the speaker usually means the output Xformer is good, but I've heard noises from speakers even with an open primary.
Work back from the output tubes. Marcus and Levy recommend momentarily touching the control grid of the output tube with a plugged in soldering iron. You'll get a loud hum if all is well. Same with the control grid of the 1st audio amp section of your detector Amp tube. Also on the high side and wiper of the volume control. You can do this with the audio output of a signal generator, but the soldering iron method is quicker. Just be careful not to touch any of the high voltage connections.
After that you need a signal generator. Put 455 KHz modulated on the green wire from the 2nd IF transformer. If you get your AF modulated tone, do the same thing to the white/green wire from the 1st IF transformer.
Check continuity in both IF transformers with reference to the schematic. Remember that the brittle and cracked rubber wire is in the IF cans, too. There are also several caps and resistors inside the 2nd IF (33), so if you're not getting any audio from the from the modulated 455 KHz on the white/green, it's one of several things to suspect.
I'm hesitant to inject the 455 KHz modulated on the primary of the IF cans because of the high voltage, even with a cap between the sig gen and the IF primary.
If at any point working backward you stop getting positive test result, you've probably found the general location of the problem. Be sure your local oscillator works. That will zero the problem down more exactly.
Try those things and get back to us.
John Honeycutt
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John, thanks for the reply. Got lazy and have not recapped yet. Powered it up with a 60 watt bulb. Initial power up bulb is not lit at all after 30-40 seconds the bulb will glow dimly. After seeing this assumed no hard faults and plugged it in. Nothing fried or over heated. Have purchased the two electrolytic caps. Inspection of the wiring....it may be brittle but it is not falling apart yet. For some reason the primary leads of the output transformer had been over heated.
The tubes have all been powered up and it appears that all filaments are operating but will verify with volatge check.
Will perform the rest of the suggestions and post results.
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I was just reading up on how this radio works. The lower right three position switch switches three tuning ranges, 540-1550Khz, 1.5-3.3Mhz, and 5.7-18Mhz. This knob needs to be turned counterclockwise to the AM freq range 540-1550Khz. The last push button on right needs to be pushed in to use the dial tuning to pick up an AM radio station. Will check tonight if that push button is in.
(This post was last modified: 04-14-2014, 11:32 AM by
rfitts46.)
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The radio does operate after I pressed the push button in all the way to the right. Good thing is after John's reply I went ahead and purchased some capacitors. I probably would have slid the chassis back in to the enclosure without recapping. Thanks John.
I also purchased a Philco 46-1203 AM radio with phonograph.