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 Post subject: Philco 32-345 alignment
PostPosted: Oct Sun 22, 2017 1:23 am 
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Location: South Carolina
Trying to align this after a recap. I can hear signal generator at 455 kc and can align this end of the scale. The procedure next wants you to tune generator and radio to 1720kc and use a small coil of wire connected to the generator lead.
When I do this i cannot hear the signal. I tried my generator on another am radio and it’s putting out the signal at 1720kc. Any ideas?


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 Post subject: Re: Philco 32-345
PostPosted: Oct Sun 22, 2017 1:42 am 
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Sounds as if the oscillator is not working. I don't have the schematic but if there is a detector/oscillator tube test for some negative voltage to the input grid. Or do the transistor radio trick.


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 Post subject: Re: Philco 32-345
PostPosted: Oct Sun 22, 2017 1:52 am 
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I have a hunch your model is 42-345. Schematic and alignment instructions here: http://www.nostalgiaair.org/pagesbymode ... 013521.pdf

I agree with thunderbird that the most likely problem is that the oscillator is dead. A good place to start troubleshooting that would be to clean the contacts of the oscillator XXL tube socket and the bandswitch. You can also try swapping the two XXL tubes in case the one in the oscillator socket is too weak to oscillate properly.

Beyond that, check to make sure the XXL oscillator tube has a reasonable B+ voltage on its plate (somewhere in the range of 50 - 150 V), and check continuity of the oscillator coil windings for the broadcast band.

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 Post subject: Re: Philco 42-345
PostPosted: Oct Sun 22, 2017 2:33 am 
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I've serviced a few of the '41 and '42 sets of late with the dual xxl front end. The oscillator plate voltage runs pretty low @ 45vdc. Not quite sure why it's design that way.

Terry


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 Post subject: Re: Philco 32-345
PostPosted: Oct Sun 22, 2017 3:05 am 
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Right it is a 42-345 oops. I replaced the two xxl tubes with some
I bought online. The vendor sent me 7A4’s in place of the XXL’s.


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 Post subject: Re: Philco 32-345
PostPosted: Oct Sun 22, 2017 3:23 am 
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That's fine. There known as XXL/7A4.

Terry


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 Post subject: Re: Philco 32-345
PostPosted: Oct Sat 28, 2017 9:06 pm 
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Cleaned the xxl tube sockets and the band switch and still nothing at 1720. Even tried the old xxl tubes, because the radio was playing a little before replaced the el. caps. I replaced a 8+8 cap with two 6uf caps in parallel. Could this cause a problem? The schematic callls for a 4+4. I tested my signal generator on another radio, it putting out signal right on the numbers.


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 Post subject: Re: Philco 32-345
PostPosted: Oct Sat 28, 2017 9:42 pm 
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Those slightly different values for the electrolytics should not be causing this problem.

Have you directly checked the oscillator function yet? If not, one good way to test is to place a good working AM radio on the bench next to your Philco and listen for the oscillator signal from the Philco. Here's how:

1. Power on the Philco and set it to broadcast band with dial tuning, and set tuning dial to 600 kHz
2. On a good working AM radio next to the Philco on the bench, listen for a signal at the Philco dial setting plus the IF frequency. In this case, that is 600 kHz + 455 kHz = 1055 kHz. If you tune around 1055 kHz on the neighboring radio, you should hear a strong "station" with no audio (maybe a little hum).
4. If you think you hear it, confirm by moving the dial on the Philco a little. The "station" on the neighboring radio should move with it.

If you hear the Philco's oscillator signal, and it has about the right frequency, then the problem is not the oscillator. If you don't hear it, then it is clear that the oscillator is the place to focus further.

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 Post subject: Re: Philco 32-345
PostPosted: Oct Sun 29, 2017 9:58 pm 
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I set the Philco at 700 and the rca at ~1255. On the rca I hear a buzzing sound. I hear no change in the rca until i tune the Philco around 1255 then the sound dips down on the rca until i tune past that spot on the Philco then the buzz on rca gets loud again. Not sure what this is telling me if anything.


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 Post subject: Re: Philco 32-345
PostPosted: Oct Sun 29, 2017 11:18 pm 
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With the Philco at 700 you should hear a signal at 1155 on the RCA. With the RCA at 1255, you should have heard a signal as you tuned through 800 on the Philco, but it sounds like you didn't. Basically, this confirms that your Philco oscillator is not working. The dip you get when the Philco and RCA are tuned to the same frequency can happen if their loop antennas are coupled by being quite close together.

Next step is to measure the plate voltage on the XXL oscillator. Should be at least a few tens of volts DC. Can you measure that voltage and let us know what you find?

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 Post subject: Re: Philco 32-345 alignment
PostPosted: Nov Fri 03, 2017 8:40 pm 
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There are 2 XXL tubes so I measured both. The outside tune measured 38vdc and the inside tube measured 135vdc. Measured both on pin 2


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 Post subject: Re: Philco 32-345 alignment
PostPosted: Nov Fri 03, 2017 10:12 pm 
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I remembered i put a used .1 cap in it that looked bad because i did not have another on hand. So i took it out and put the old .1 cap back in. It started playing great all across the dial. So I fired up the signal generator to peak it. Then it quit again, nothing on the 1720 end. Strange, maybe a loose wire or something?


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 Post subject: Re: Philco 32-345 alignment
PostPosted: Nov Fri 03, 2017 11:34 pm 
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Pretty good chance that both your 0.1 uF caps are bad. Best to get a new one in there.

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 Post subject: Re: Philco 32-345 alignment
PostPosted: Nov Sat 04, 2017 1:29 pm 
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Replaced the suspect cap with a new one. Still not oscillating. Nothing. It played great for a few minutes. Now i am back to square one again


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 Post subject: Re: Philco 32-345 alignment
PostPosted: Nov Sat 04, 2017 3:48 pm 
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Is this a .1 cap 104k?


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 Post subject: Re: Philco 32-345 alignment
PostPosted: Nov Sat 04, 2017 5:01 pm 
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No, that is a 220 ohm resistor, probably 2 watts.

I can't see the color of the third band very well in your picture. 220 ohms if red-red-brown. 2.2K if red-red-red.

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 Post subject: Re: Philco 32-345 alignment
PostPosted: Nov Mon 06, 2017 2:55 am 
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Went through and replaced all the caps except the micas. Radio is still not oscillating. It played for a while and then quit. Nothing since then. I can hear signal generator at 455hz. But at 1720hz you get no signal from the generator at all. But when I tune my signal generator to 1720 and the radio also I get no sound from the generator but I can hear some faint stations come in. When you take the generator off 1720 it goes back to nothing but static. Do the voltages I posted earlier seem right?


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 Post subject: Re: Philco 32-345 alignment
PostPosted: Nov Mon 06, 2017 4:35 am 
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The voltages are plausible. Your signal generator is functioning in place of the radio's oscillator. You'll probably find that if you move the signal generator dial, you can tune in different stations.

I'd recommend replacing micas that are tied directly to the mixer/oscillator circuitry as a next step.

You may also want to check for any out-of-tolerance resistors in the radio. Tolerance range of +/- 20% is generally OK.

Have you cleaned the bandswitch contacts? That's another high failure point in these types of radios. You may even want to check resistance of all contacts that are supposed to be making contact on the BC switch position. You generally want to see 1 ohm or less.

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 Post subject: Re: Philco 32-345 alignment
PostPosted: Nov Wed 15, 2017 3:33 am 
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You haven't said anything about the other bands, whether or not your getting reception. I've done two 345's in the last few months and had nearly the same problem as you have with both of them and discovered that the band wafer switch was the culprit to a degree along with the osc coil. The coil I heated with a hair dryer til the wax started to flow and checked the radio reception and it started to receive stations well. But the wafer switch you could tell that it wasn't quite right when you hear considerable scratchy noise coming from the switching of the wafer contacts. I think that the dust buildup on the coils can have an effect on the coils ability to function properly. And these were pretty dirty.

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 Post subject: Re: Philco 32-345 alignment
PostPosted: Nov Sat 18, 2017 6:46 pm 
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I found some time to work on my Philco this morning.

1. Extensively cleaned the band switch with contact cleaner and a Q tip, It was really not that bad. Some black came off of it. I checked every wire going to it
with a voltmeter. They were all good. The switch seems in really good shape compared to some I have seen. I checked every other wire on the radio.

2. I checked the broadcast coil, it was not open and all the wires going to it are good.

3. I checked the Oscillator coil, It was not open, It is hard to clean off dust with that soft wax. It is dirty. All the wires to it are good.

4. Checked the filament on both xxl and 7b7 tubes, there are 2 of each. The heater filaments are good between pins 1 and 8. (I do not have a tube checker).

5. I fired up my signal generator. Signal good at 455kc connected to radio antenna. But using a loop, Signal cannot be picked up at 1720kc on Broadcast band nor
anywhere else on this band. It actually played great for a short time the other day and then quit. It played some on the broadcast and shortwave before I
did the recap.

6. Tried the other bands out with signal generator, nothing on Shortwave, but the signal from the generator can be heard at 6.7 mc on the Police band and I actually picked
a talk show on the police band for a few minutes, (This radio likes to tease me, when I was just about to quit)

7. I did not replace the micas around the switch, I do not have any on hand.

Not sure where to go from here. Do I melt off all the wax on the coils with the hair dryer or just enough to get it clean? Any other suggestions would be appreciated.

Thanks for the help....


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