10-15-2011, 10:24 PM
Can someone tell me the resistance of a philco 7439 volume control.
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volume control
10-15-2011, 10:41 PM
If it is for the model 80 it's 20K. Two quick checks, one unplug set turn volume all the way up. Measure resistance from ANT post to chassis ground. Should be very low like a few ohms. If not antenna coil primary is open. Two, Turn volume all the away down.Measure resistance from antenna post to chassis ground. Should read about 20,000 ohms. If not check volume control, open or bad ground connection.
How's your oscillator doing? 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 it! Terry 
10-15-2011, 10:42 PM
What model Philco are you working on?
I didn't see any data on your part number on Philcorepairbench.com. -Keith
10-16-2011, 07:30 AM
Terry is correct, it is 20K. Part no. 7439 was used in model 80 and the three-knob 81.
-- Ron Ramirez Ferdinand IN
10-16-2011, 08:06 AM
Do I get a prize????
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 it! Terry
10-16-2011, 09:17 AM
Yeah - a Philco 84B that needs complete restoration.
 
-- Ron Ramirez Ferdinand IN
10-16-2011, 10:11 AM
I unsoldered one outer lug, not the one to ground and measured it like a resistor, 17 ohms.
Strange, then I unsoldered the center lug and it read 27k. I thought you can measure a pot like a resistor if one of the outer lugs is disconnected.
10-16-2011, 11:24 AM
Depending on the circuit this may not be true, IE this case. However if the wiper is all the way toward the still connected end you should be able to get an accurate reading. Then you could connect the ohmmeter between the center and unconnected end and sweep it, and you will then see if there are any open spots.
10-16-2011, 06:02 PM
It also maybe effected by the very low resistance of the antenna coil connected to the wiper and ground.
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 it! Terry
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