Early Model 89 Tone control-Figured It Out, Maybe - Printable Version

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+--- Thread: Early Model 89 Tone control-Figured It Out, Maybe (/showthread.php?tid=4725)

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Early Model 89 Tone control-Figured It Out, Maybe - Pepperoni - 05-10-2012

My model 89 has the tone control that is referenced in the first drawing in the following link. If I did the link correctly. The .015ufd cap and the .01ufd cap are tied together inside the tone can and are soldered to the pad (which has a lug on it) and is not grounded. The wiper switches on and off of this pad. The other end of the .01ufd cap goes to the plate of the 42 output tube and the other end of the .015ufd cap is soldered to the frame of the tone control can which is also not grounded.
http://www.philcoradio.com/tech/89evol.htm

I have my 490K resistor connected to the 7E .05 cap which ends up at the CT of the high voltage output. But there is no place for me to connect the 490K and the 7E .05 cap to the .015ufd section of the tone control unless I connect the two to the same place as the .015ufd cap which is the frame of the tone can. This is not the way the radio was wired so I don't know how the tone was working without the 7E .05 cap and the 490K resistor. Or will it work that way?

So what should I do? Redo my tone control can and make it per the 2nd drawing on the referenced link?

EDIT: I think I have this figured out without having to pull the new caps out of the already re-potted tone can. Just a matter of switching a couple of wires coming off of the caps in the tone control can and then routing and connecting them accordingly to make it match the 2nd schematic on the referenced link. I will have to ground the "Un-grounded" lug on the tone can frame and the high and low tone frequencies will be reversed when I switch from "bass" to "treble". Doesn't matter to me. It's only a two position switch anyway.

Thanks to those of you who viewed this and probably said... "What the heck is he trying to say?"

Pepper

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