volume control - Printable Version
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volume control - johnfin - 10-15-2011
Can someone tell me the resistance of a philco 7439 volume control.
Re: volume control - Radioroslyn - 10-15-2011
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
Re: volume control - ipwizard - 10-15-2011
What model Philco are you working on?
I didn't see any data on your part number on Philcorepairbench.com.
Re: volume control - Ron Ramirez - 10-16-2011
Terry is correct, it is 20K. Part no. 7439 was used in model 80 and the three-knob 81.
Re: volume control - Radioroslyn - 10-16-2011
Do I get a prize????
Terry
Re: volume control - Ron Ramirez - 10-16-2011
Yeah - a Philco 84B that needs complete restoration.
Re: volume control - johnfin - 10-16-2011
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.
Re: volume control - codefox1 - 10-16-2011
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.
Re: volume control - Radioroslyn - 10-16-2011
It also maybe effected by the very low resistance of the antenna coil connected to the wiper and ground.
Terry