04-13-2014, 11:57 PM
Rich,
If you are certain that the tone control is wired properly and there are no obvious problems in the audio section, the next place to look is the power supply. Make sure the polarities are correct for the electrolytics and that all of the connections are correct. You really should be able to feed some audio signal into the audio section of the receiver.
If all else fails, make a clean copy of the schematic, get out your colored pencils, and trace the entire thing. As I go through a radio I mark each section of the schematic as I verify that it is connected as it should be. I also check values for every resistor, capacitor and inductor and mark the schematic accordingly. It helps enormously to be compulsive, patient and systematic. If you have a wrong resistor, you should be able to find it.
I wouldn't play too much with the trimmers until you are ready to align the set. It only takes a small turn to really mess up the alignment and make life more difficult down the road. The only way to align the set is to be able to feed RF and IF into the circuit, and it doesn't sound like you are at that stage yet. Don't worry. Trace out the schematic, verify each connection and component, and you will be there soon enough.
My Philco 60 was rather touchy with the alignment. First, the tuning capacitor on my set is quirky. You can turn the dial and move the plates past the point at which the capacitance actually changes. To avoid this, I had to make sure that the dial pointer hit 1500 kHz before the capacitor reached the plateau point. Once I did that, I could align the RF section without much difficulty. Second, it made a big difference to clip a lead to the AVC line and use that voltage as my adjustment point. I usually attach my oscilloscope across the secondary of the audio output transformer and adjust from there, but it wasn't giving great results. After some reading, I saw where several people had better luck using the AVC line for alignment, and I had much better success with this method as well. This may become my new standard protocol.
Keep plugging away at it, and don't get discouraged. There will come a point where music will come out of your set, and believe me, it will be some of the sweetest music you have ever heard.
Roger
If you are certain that the tone control is wired properly and there are no obvious problems in the audio section, the next place to look is the power supply. Make sure the polarities are correct for the electrolytics and that all of the connections are correct. You really should be able to feed some audio signal into the audio section of the receiver.
If all else fails, make a clean copy of the schematic, get out your colored pencils, and trace the entire thing. As I go through a radio I mark each section of the schematic as I verify that it is connected as it should be. I also check values for every resistor, capacitor and inductor and mark the schematic accordingly. It helps enormously to be compulsive, patient and systematic. If you have a wrong resistor, you should be able to find it.
I wouldn't play too much with the trimmers until you are ready to align the set. It only takes a small turn to really mess up the alignment and make life more difficult down the road. The only way to align the set is to be able to feed RF and IF into the circuit, and it doesn't sound like you are at that stage yet. Don't worry. Trace out the schematic, verify each connection and component, and you will be there soon enough.
My Philco 60 was rather touchy with the alignment. First, the tuning capacitor on my set is quirky. You can turn the dial and move the plates past the point at which the capacitance actually changes. To avoid this, I had to make sure that the dial pointer hit 1500 kHz before the capacitor reached the plateau point. Once I did that, I could align the RF section without much difficulty. Second, it made a big difference to clip a lead to the AVC line and use that voltage as my adjustment point. I usually attach my oscilloscope across the secondary of the audio output transformer and adjust from there, but it wasn't giving great results. After some reading, I saw where several people had better luck using the AVC line for alignment, and I had much better success with this method as well. This may become my new standard protocol.
Keep plugging away at it, and don't get discouraged. There will come a point where music will come out of your set, and believe me, it will be some of the sweetest music you have ever heard.
Roger
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