Posts: 74
Threads: 42
Joined: May 2008
City: Shinnston, West Virginia
State, Province, Country: USA
I am helping a friend with his Philco 42-327 code 122. He has changed the filter capacitors and all of the paper capacitors. I am using the negative side of the electrolytic capacitors for the voltage measurements. At the cathode, pin 7 of the 35Z3 rectifier I measure 120 volts and 126.4 volts with 2 different meters. The voltage should be 108 volts DC. I am receiving no stations. The local oscillator grid, pin 4 of the 14AF7 measures -4.3 volts. When I inject the 455 KHz IF frequency into the set, I get an oscillation riding on the signal instead of a clear 455 kHz IF frequency sound. All suggestions are appreciated. Thank you.
nv3g
Oscar
Posts: 7,294
Threads: 268
Joined: Dec 2009
City: Roslyn Pa
So where are you injecting the 455kc signal? At the antenna? or At the plate of the mixer. Detector and audio stages seem OK? The 20v or so extra isn't too much to be concerned about.
Terry N3GTE
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
Terry
Posts: 74
Threads: 42
Joined: May 2008
City: Shinnston, West Virginia
State, Province, Country: USA
I was injecting the signal into the grids of the 7B7's. I just discovered something that may be the problem. I can inject an audio signal into the control grid, pin 5 of the 50L6 and it sounds fine. Then inject an audio signal into the control grid, pin 3 of the 7C6 and it sounds fine. When I inject an audio signal into the top of the volume control, I get audio with undesired oscillations. I suspect the volume control. I will check that out on Friday. Thank you for the suggestions.
nv3g
Oscar
Posts: 7,294
Threads: 268
Joined: Dec 2009
City: Roslyn Pa
DeOxit works well on volume controls. In a pinch WD40 any bad either.
Gud lk OM
Terry
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
Terry
Posts: 74
Threads: 42
Joined: May 2008
City: Shinnston, West Virginia
State, Province, Country: USA
My apologies. Capacitor 30 was missing. Also did not have the band switch figured out. Left is Police, Center is Broadcast, and Right is Shortwave. I have the band switch in the Left position. My error. The radio now plays nicely in the center ( Broadcast ) position.
Thanks for all your input.
nv3g
Oscar
Posts: 7,294
Threads: 268
Joined: Dec 2009
City: Roslyn Pa
Great ! glad to hear you got it all worked out.
Terry N3GTE
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
Terry
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