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Philco model 70 rebuild - by Tim P.
#74

THE GREMLIN LIVES! There arent too many problems as irritating as a persistant intermittent that fixes itself, then breaks again. I recall the washer on the volume control as ok. Right now, I have the control bypassed with a series of fixed resistors, and it behaved for several days, then - it returned! I have been playing the radio almost daily by the bench while on another project. I had determined the problem is in the signal circuit, not the power supply. I have tapped, froze, flexed and checked to the point of stupidity. Anyway - I think I may have found the culprit, or at least, something that is contributing to the problem. The #4 trimmer on the tuning cap. It had been real touchy when aligning and crackeled a lot. I had tapped and messed with it, but finally I hit it a certain way with a plastic tool, and bingo! The volume started jumping and the crackeling started. It is way worse on the higher freq's, which is how I found it. I usually listen to a station at 800khz. It is also right beside that hot running 47 output tube.

I was suspicious of this before and removed the screws and cleaned, but didnt get it to act up since. Now, I can push on the washer on the side near the tube and sometimes get the crackeling sound and the volume jumps up or down. Sometimes not. I am not talking about pushing down in a way that will adjust the cap, as I have done this and know how it sounds. This sounds like a bad connection somehow. I had a lot of trouble when adjusting this one. Has anyone removed and cleaned this or replaced this part? Any thoughts?

If I could find the place called "Somewhere", I could find "Anything" Icon_confused

Tim

Jesus cried out and said, "Whoever believes in me , believes not in me but in him who sent me" John 12:44


Messages In This Thread
Philco model 70 rebuild - by Tim P. - by TV MAN - 01-29-2014, 11:46 AM
RE: Philco model 70 rebuild - by Tim P. - by TV MAN - 03-25-2014, 10:11 AM



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