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Philco Tone control nº 30-4178 - Printable Version

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Philco Tone control nº 30-4178 - edison - 12-30-2021

Hello.

I'm restore my Philco 245, and would like to know the values of the tone control capacitors (part no. 30-4178).
In the schematic the values are not clear.
I believe that one condenser is 1.000 pf, another is 10.000 pf, but I can't see the value of the other.
As it is the middle capacitor, it must be a value between the two.
Will it be 5.000 pf?


Many thanks

RE: Philco Tone control nº 30-4178 - Radioroslyn - 12-30-2021

It depends on how the switch works. If it sweeps across connecting shorting more of the caps together or does it select each one separately? If in shorting the caps are going be smaller in value vs selecting as they are going to add up. The old Philco set were set up like that. Later on when the tone control got more advanced with tapped volume controls and such the switches had to pick off different points in the circuit to accommodate the bass boost.

All in all the value of the middle cap isn't particularly critical. I'd go w/the .005mfd as you mentioned.

RE: Philco Tone control nº 30-4178 - morzh - 12-30-2021

1.000 pf - one picofarad is a really, really small value. If however you mean something else, well, Ameriocan notation uses a comma for separating thousands.

RE: Philco Tone control nº 30-4178 - Ron Ramirez - 12-30-2021

P/N 30-4178 is also used in American models 29 and 45.

The Model 45 schematic does not give the values of the condensers, but the 29 schematic does.

The first cap is .01 uF or 10 nF.
The third cap is 3000 pF or 3 nF.
The second is nearly impossible to make out. It is either .02 uF, .03 uF, or .05 uF. (20, 30, or 50 nF, respectively).

I believe I would split the difference and use .03 uF for the second one. It isn't going to make that much of a difference in tone quality, especially since these are not high fidelity units anyway.

RE: Philco Tone control nº 30-4178 - Mondial - 12-30-2021

The recently posted service bulletin for the model 29 has a much clearer schematic and it shows the middle cap as .02 uf.

These scanned service bulletins are a big improvement over schematics taken from the old Rider manuals and other previous sources. Its great that they are now posted in the library!

Thanks to those who scanned and made them available.

https://philcoradio.com/library/download/service%20info/service%20bulletins/Philco%20Service%20Bulletin%20195.pdf

RE: Philco Tone control nº 30-4178 - edison - 12-31-2021

Hi.

morzh:  sorry, but I meant a thousand and not one. I used the dot and not the comma.

Thanks Ron and Mondial.

In the diagram of the model 29, the values of the capacitors are perfectly visible.

Thank you all.

Best regards and happy New Year.