The PHILCO Phorum

9/12/20
Hey folks.  I did a total recap on 53-1750 radio/phonograph about 3 years ago.   Has been running like new all this time,  but lately it still works with low volume but  if I turn the volume beyond a low volume,  I get a  LOUD high pitch squeal with no other sound. 

 Doesn't matter if it's the phono or the radio, same squeal.    All tubes test good and replacing them from another working set does not help.  I thought perhaps it was the volume/tone control, but a new one made for me by Mark Oppatt did not solve the problem.  All 5 electrolytic capacitors were removed from the circuit and tested - all are good with both a capacitance meter AND and an ESR meter.  Before I go replacing all the caps again, any suggestions as to what part of the circuit(s) this squeal may be coming from?   If I tap around, it doesn't seem like anything is loose   Thnx

Any shielded tube that should have it's grid cap inside the shield and doesn't?
Or tone control caps....or the cap in parallel to the audio primary?

I would check C19, C17, C18 those number are from looking at model 53-1754 could not find info on a model 53-1750. Stay safe David

I do not even see the 53-1750 model in Riders online.

You guys are good.  After rechecking connections with a magnifier and bright light, I found this bad connection on this cap where it was soldered on to the buss terminal. I would have never noticed it without the magnifier -  after a re-solder, the set works good as new again.   

Thanks for your help.