12-30-2011, 06:43 PM
Well, folks, back in the spring I said I would restore this 37-650 chassis that I had out in the garage. It was the best looking of the three 37-650 chassis which I owned. I planned to trade this chassis, once restored, for another radio.
The main part of the chassis went smoothly without any significant issues.
Then came the RF unit.
I was dismayed to find that it would work intermittently...and when it stopped working, a tiny bit of smoke would start to emit from one of the band switch wafer sections in the oscillator section of the RF unit.
Okay, a burned carbon track in the switch wafer. It had happened before to a 37-650 I had serviced, and I was able to remove the carbon track from that switch wafer and fill the resultant gap with epoxy, after which the radio worked fine.
Not this time. I could not find the carbon track!
So...I tried the oscillator section from the worst of the other two 37-650 chassis I had. The switch wafers were fine...but band 3 (the highest SW band) would not work! It produced only static noises but did not tune any stations.
Next, I removed the Band 3 oscillator coil from the oscillator section which was smoking in the switch wafer, and installed that coil in place of the Band 3 coil from the replaced oscillator section.
Result...same problem.
The odd thing is, both oscillator coils had good continuity. But I have learned from servicing 1937-38 Philcos in the past, that "good continuity" does not always equal "good coil."
So, in desperation, I pulled the entire RF unit from the 37-650 chassis I had planned to keep for myself.
You guessed it...that solved the problem and the set now works on all three bands.
Here are a couple photos of the now restored 37-650 chassis in action.
[Image: http://www.philcoradio.com/images/phorum...0001-1.jpg]
[Image: http://www.philcoradio.com/images/phorum...0002-1.jpg]
The main part of the chassis went smoothly without any significant issues.
Then came the RF unit.
I was dismayed to find that it would work intermittently...and when it stopped working, a tiny bit of smoke would start to emit from one of the band switch wafer sections in the oscillator section of the RF unit.
Okay, a burned carbon track in the switch wafer. It had happened before to a 37-650 I had serviced, and I was able to remove the carbon track from that switch wafer and fill the resultant gap with epoxy, after which the radio worked fine.
Not this time. I could not find the carbon track!
So...I tried the oscillator section from the worst of the other two 37-650 chassis I had. The switch wafers were fine...but band 3 (the highest SW band) would not work! It produced only static noises but did not tune any stations.
Next, I removed the Band 3 oscillator coil from the oscillator section which was smoking in the switch wafer, and installed that coil in place of the Band 3 coil from the replaced oscillator section.
Result...same problem.
The odd thing is, both oscillator coils had good continuity. But I have learned from servicing 1937-38 Philcos in the past, that "good continuity" does not always equal "good coil."
So, in desperation, I pulled the entire RF unit from the 37-650 chassis I had planned to keep for myself.
You guessed it...that solved the problem and the set now works on all three bands.
Here are a couple photos of the now restored 37-650 chassis in action.
[Image: http://www.philcoradio.com/images/phorum...0001-1.jpg]
[Image: http://www.philcoradio.com/images/phorum...0002-1.jpg]
--
Ron Ramirez
Ferdinand IN
