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Philco 38-690 electronics restoration.
#97

Still some ails that plague it. One is this switch, the BC band secondary solders to the switch contact that is unreliable. No good way to reach it.

Then there's an open coil primary at the 2nd band, which I think I'll leave be as it is the police etc band, not much there anyway. Other bands I aligned.

Then the dial...am not sure as to it being exact same with internal ring, as in 37-116 deluxe, as then it means the inner ring is missing and someone riveted a piece of aluminum to the opposite of the stub that used to hold the ring and now he two are used to hold the dial which otherwise is good, but it slips and not held reliably.

Then there was this hum. Pretty pronounced. Right across the bass field coil I saw a pretty large ripple. I tried caps tono result. Then I started tacing it and traced to the power amp 6F6 input. That traced to the tuner output, the second audio 6N7, metal case. I realized the capacitor that is the output of it was hidden and I didn't restuff it. Fixed it, again to no result. So I cannibalized my 37-116 chassis with a glass 6N7G and....the hum went down a lot.
Then I looked at the second 37-116 chassis and it had a metal 6N7, same as I have, and after the change the hum was practically gone.
That was the tube!!!! The ripp!e on the scope also went way down.
The tube did test well - I tested all of them.

Well, at least some good news for today.

People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.


Messages In This Thread
Philco 38-690 electronics restoration. - by morzh - 04-12-2017, 08:19 PM
RE: Philco 38-690 electronics restoration. - by morzh - 11-26-2017, 09:47 PM



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