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Hello all, I have my Philco model 19H chassis 128 here with the schematic showing the volume control pot with a part # 33-5000. In my radio is a part # 33-5425-2 and stamped under that is 1-230. This is a tapped pot, but the schematic says it should be "20K ohms to tap" but mine is 200K to the tap. The overall value is correct, 350K. I took the pot apart and cleaned it, it appears and checks out to be in good working order. I am not sure if this was ever replaced, but the mystery here is that there is a 10K resistor going to the 4 point bass compensating tone control switch that is supposed to go to the tap on the volume control but was never connected. I am going to assume there is a typo in the schematic and connect it. Any thoughts would be appreciated, thanks!
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http://www.philcoradio.com/tech/19evol.htm
Look at the last schematic on that page (Model 19, Code 128 ). It shows the 10K resistor, part (39), between the volume control tap and the tone control. Yes, it should be connected to the tap, else the tone control will have no effect save for the fourth position (clockwise).
How are you measuring the resistance to the tap? It should be measured from the grounded end of the volume control to the tap.
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Ron Ramirez
Ferdinand IN
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Hi Ron, yes- I am measuring from the grounded end to the tap and I am getting 150,000 ohms. Does my part number make sense? Thanks a lot!
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I would have to go find a Philco parts catalog...they are all in the basement, and I'm upstairs...
So it's 150K to the tap. I'm wondering if your replacement control is linear taper rather than audio taper? It would still work...but you won't get much control of your volume with a linear taper control...
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Ron Ramirez
Ferdinand IN
Posts: 50
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City: Wyoming, PA
Thanks a lot Ron, glad to be a member of this forum! Next I have to figure out the Shadow meter and the best type of AM antenna to connect to this thing!
Posts: 13,776
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According to the 1941 Philco parts catalog, 33-5425 is a 500K control, logarithmic (audio taper), with a tap at 250K.
G'ahead, try it, should be OK.
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Ron Ramirez
Ferdinand IN
Posts: 50
Threads: 14
Joined: Dec 2014
City: Wyoming, PA
