Philco 91 code 225 - Printable Version

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+--- Thread: Philco 91 code 225 (/showthread.php?tid=20844)

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Philco 91 code 225 - Tom45acp - 01-09-2020

I have been unable to find a schematic for this chassis. Anyone know if one even exists and where I might get a copy?

I've been working off of a schematic for chassis 126 & 226 and it seems to be accurate but I have a capacitor in my radio that doesn't show up on this schematic. It is in a small metal enclosure but not like the rectangular ones elsewhere in this radio. It is wired to the BC resistor which consists of an 85 ohm and 205 ohm section. One lead of the capacitor in question wired to the junction of the two resistors and the other lead is connected to the chassis. Stamped into the metal case is 50835, searching for this part number yields no results.

The metal case is soldered to the chassis whereas all other parts use screws or nuts and bolts. Makes me wonder if this was a factory installed part.

The cap measured .246 mfd, but I don't know if that number is reliable.

Does anyone know the real value of this cap? Should I leave it in place or replace it with a 
.25 mfd cap?

Any leads or advice would be appreciated.

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RE: Philco 91 code 225 - Radioroslyn - 01-09-2020

It would appear that it's used to decouple the audio signal out of the bias voltage going to the control grids of the 42's. That this point there is little voltage there like -20v. You could use a small electrolytic cap a few mfds @35 or 50v but be sure to connect the + side to the chassis and the - to the BC resistor.

OBTW Welcome!

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RE: Philco 91 code 225 - Tom45acp - 01-10-2020

Thanks for the information. I'm still getting used to the fact that the chassis can be a conductor for several circuits units at the same time.

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