1951 19" Zenith Porthole 1951 24H21 sound issue
 

Recent full recap, tubes etc. and slowly pulling it out of it's slumber...

I am now getting a decent picture but I have a nasty background static noise although I can hear everything broadcasted clearly.

I have tried every adjustment on that tv there is and have only been able to moderate it to some extent.
I am using only rabbit ears. There is no affect whatsoever to anything that comes on the screen...just constant slightly irratic buzz. I replaced some resistors with metal film and now I am replacing those with carbon thinking maybe they are causing interference.

I don't think it is the audio output amp generating the static because when inject 1K sound just after all the video stages I get a nice clear signal.

I keep thinking either low or high voltage is somehow getting affecting the sound but I am not competent enough to first eliminate a video getting in.

I am new to this and trying to figure out how to inject a signal though the video stages right after the tuner or audio output. Can you lead me down the best pathways?

As always,
Thanks
Stan

The '51 porthole I used to have had an AGC adjustment pot on the back of the chassis. It was for reducing the buzz in the audio. If it is a buzz that you get you might try adjusting that if your set has one.

Put a scope on the B+ line and see if the noise is there. Could be either a bad single-section electrolytic, or a multi-section with one or more sections going bad. I've stirred up both audio and video noise demons by just changing a couple of parts myself. Also check to see if you may have flowed any flux onto the tube pins when replacing parts; a shot of flux remover or De-Oxit/Rid-Ox sometimes helps, it helps, too, if a long-undisturbed tube gets bumped to a dirty spot on one or more pins.