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silvertone no/low volume need some advice - Printable Version

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silvertone no/low volume need some advice - conroyp - 10-13-2014

Hey gang,

finally got this project out and re-started working on it. It came out of my grandmothers house, 1930's sears silvertone 101.566--D. When I first check it out  it had very low volume....barely audible unless I hooked it to a longwire antenna, but tuned ok.

It has since been recapped, new resistors, power cord, tubes and im working a little on the cabinet too.

I have checked the speaker, volume control, tubes, with tester and by changing them as well, tuner coils, rf coil have continuity, I have not done a formal alignment but have turned the IF adjustment screws slightly with no improvement.  

It tunes to local stations just fine, but the low volume is unchanged, I need some guidance on what to look at next.

http://www.nostalgiaair.org/PagesByModel/529/M0017529.pdf

[Image: http://i818.photobucket.com/albums/zz105/5X8Rider/DSCF2064_zps58f878e0.jpg]


[Image: http://i818.photobucket.com/albums/zz105/5X8Rider/DSCF2066_zps1dfc1d92.jpg]

[Image: http://i818.photobucket.com/albums/zz105/5X8Rider/DSCF2063_zpsa94a2119.jpg]
thanks,
pete

RE: silvertone no/low volume need some advice - morzh - 10-13-2014

1. How's your R3 (volume pot) is doing? Have you checked it?
2. have you checked all your tubes? A weak tube, especially the first two, will do it too you.

RE: silvertone no/low volume need some advice - Arran - 10-14-2014

 I think it's time to do some voltage checks, starting with the output of the 35Z5 on the input filter capacitor and working your way along checking the plate and screen grid voltage on each tube. One common culprit is the plate resistor on the 12Q7/12SQ7 tube, but if the tube is weak that will also effect the volume. The second IF transformer also has a fixed mica cap inside, a .00015 uf, that is paralleled with the volume control, if those have a habit of going bad that could cause a problem. There is another mica that runs between the plate of the 12Q7 and B- (C11), that could also cause low volume if leaky, but a voltage check will tell.  What is puzzling is why adjusting the trimmers on the IF cans doesn't do anything, if it doesn't make the radio perform better then playing with them should make it worse, or is it just that it does not make it better?
Regards
Arran

RE: silvertone no/low volume need some advice - conroyp - 10-16-2014

thanks, Morzh, arran....all the tubes were checked, and replaced as well, the volume pot meaures ok on a ohmmeter but I didnt test it under any load.
The IF adjustments dont make it any better, they are loudest at their origional positions.
ill get back into it and focus on checking out the voltages and resistance inside IF transformers and their associated caps and resistors.