I have this formally wonderful Columbia 360 record player that was handed down through my family. After some lubrication and cleaning to the changer it worked and sounded great for 2 years or so. Slowly it developed a low hum...you guessed it now there is no sound.

Before I start rebuilding the amp is there anything I should check to verify there is no major damage that won't be easily repaired?

I attached a photo of the schematic since I see no specific model numbers. Amp is listed as Series B amp and cabinet 2201.

Thanks in advance for your time and assistance.
Bill

http://imgur.com/OL9Ij

http://i.imgur.com/OL9Ijl.jpg (http://imgur.com/OL9Ij)

Sounds like the electrolytic filter caps took a dump. Sounds like it's in need of a re-cap.

That's what I thought as well but would bad caps alone cause no sound not even hum?

Do the tubes light? Is there B+? Is the speaker properly connected?

Maybe a tube bit the dust. You need to check tubes and voltages first.

As long as the output transformer (rightmost on the schematic) has good windings,
this amplifier is easy to rebuild. All other parts are esaily available.

This is a rather basic amp, with series-string tubes, but being a push-pull unit
(two output tubes), it may be worth keeping and rebuilding, as noted above.
Good luck!

Thanks for all the advice!

The windings seem okay as best as I can tell, VOM reads 196 ohms and the tubes do light.

I'll let you know how it turns out.

Bill

Often, the filter caps cause hum and then the cap becomes very leaky or shorts. When this happens, the shorted/leaky caps will destroy the rectifier tube and/or the surge resistor in the power supply. When this happens, the amp will be dead because there is no B+ voltage being developed. Since the output transformer test good, I'd replace the electrolytic and paper caps and then I'd check voltages.

Thanks for all the advise. So far I've replaced the electrolytic and paper caps (no change) then changed 35Z5GT. Now I have low hum but no audio from the cartridge. Cartridge is working when connected to a known good amp (used aux in on receiver). Next I'll change the 12AX7, will let you know what happens when the new tube arrives.