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Resurrecting Silvertone

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Post by Cbmorgan91 Thu Dec 17, 2020 5:47 pm

After replacing capacitors, I'm slowly trying to bring this radio to life. I am new to the hobby and new to electronics. I'm getting a little static as I go across the dial. I started checking voltages at the different pins on each tube and here are my findings.
12BE6
Pin 6 =92V pin 5= 91V pin 1= 0
12AT6(1)
Pin 7= 29V
12BA6
Pin 5= 0V pin 6= 93V pin 7=0V
35C5(2)
Pin 7= 127V
Pin 1= 6V
35C5(1)
Pin 6= 0V
Pin 7= 30V

Can anyone help me understand what's going on here? Thank you for any help You can give me.

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Post by Cbmorgan91 Thu Dec 17, 2020 5:49 pm

Resurrecting Silvertone Snapch11Resurrecting Silvertone Snapch11

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Post by mr_ed01 Fri Dec 18, 2020 12:09 am

Measure the voltage at the ungrounded end of C6 (IF transformer T2 pin 4). If B+ is measured there, zero volts at pin 5 of the 12BA6 would indicate the primary winding of IF transformer T2 is open.

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Post by AJ2X Mon Jan 18, 2021 12:16 pm

With zero volts on pin 6 of both audio output tubes, it looks like R19 is open, but that would mean no high voltage for the converter and IF tubes. So something in your measurement may be off.

In this "hot" chassis, the metal chassis itself is not DC ground. Notice the 2 types of ground symbols at the very bottom of the schematic: the upside-down parallel-lines triangle is the DC ground ("B-"), and the rake symbol is labeled "chassis ground." They're separated by a capacitor C13. So you'll need to measure DC voltages from the "B-" point to the various tube pins.

The fact that you "get a little static" as you tune says that there IS high voltage to the RF section, and to the audio as well. The first place I'd look is the radio-phono switch. Switch contacts get dirty so a squirt of DeOxit or other cleaner may get you going (after working the switch several times to clean it). If still no signals, touch a screwdriver to the phono input (with the switch in the phono position) and you should get a good (ugly) buzz, variable with the volume control. That would indicate the audio section is (mostly) OK and you can concentrate on the radio portion.

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