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 Post subject: Re: Silvertone 2015 Tube Radio
PostPosted: Apr Sun 05, 2020 10:14 pm 
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Joined: May Sun 13, 2012 8:12 pm
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Location: Central PA 16801
i still say there is a miswire, wrong component, or some leads touching.

bounce all the wiring and parts in the chassis against the schematic.

bounce the schematic against the chassis.

do this three times.

these are really good straight forward sets.

check the IF cans on their primary and secondary for continuity. it should be anywhere between 10 and 25 ohms, maybe up to 30 per coil.

steve

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 Post subject: Re: Silvertone 2015 Tube Radio
PostPosted: Apr Mon 06, 2020 1:20 am 
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Joined: Feb Mon 21, 2011 4:19 pm
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Location: San Marcos, CA 92069
Marko582 wrote:
I haven’t responded because I have been under the weather. Today I decided to put the original tubes back in the radio and I now get low volume with the control up all the way. When I turn it down all the way I get low pitch hum boat motor sound and the dial flickers with the sound?? I get one station with full volume it’s just low. New tubes don’t make any difference.

My first thought is a piece of a snipped lead, or solder, has rolled around and shorted something out. As other have suggested, pull the tubes and lightly rap the chassis with a wood block or nylon/wood hammer over some paper and see if any solder or snipped leads fall out. If any does fall out, put the tubes back in and see if that fixed the problem.

If this was my radio, I'd be checking DC voltages at each filter capacitor. The first off of the 35Z5 15ohm resistor should be in the 120 to 130V range. The second after the 1K ohm resistor should be in the 85 to 90V range. Also check the 150ohm cathode resistor voltage on the 35L6, it should be around 5 to 6 volts.

Your radio is a floating chassis, connected to the B- ground by C12 (0.05uf) and R5 (330K). I'd measure the resistance with the radio unplugged between B- and the chassis. If it is less than 330K, something is shorting to the chassis.

If the voltages check out OK, and the chassis to B- ohms out to 330K, then I'd double check the plate voltages of the other tubes against the schematic. The two 12SK7s and 12SA7 should be close to 70V, the 12SQ7 should be about 50V.

If that all checks OK, then I'd try and isolate if the problem is RF or audio. Set the tuner so you don't hear any stations, then touch a meter probe to the center tap of the volume control with it turned up, you should hear a very noticeable buzz if the audio section is working.

I hope this helps!


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 Post subject: Re: Silvertone 2015 Tube Radio
PostPosted: Apr Wed 08, 2020 3:55 am 
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Joined: Dec Sat 24, 2011 9:17 pm
Posts: 6022
Location: Vancouver Island, Canada
Could there be a cold solder joint in front of the volume control? It worked when all connections were fresh, but that one connection moved or came loose.
Go over your work with a hot iron, especially connections involving several wires and leads, and terminals on the chassis or on large components that take longer to heat.

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