Electrolytic Cap 30-2409 Question - Printable Version

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+--- Thread: Electrolytic Cap 30-2409 Question (/showthread.php?tid=23210)

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Electrolytic Cap 30-2409 Question - cdoyal - 01-16-2022

I believe this is a 12 mfd cap. Is it safe to ASSume the red lead is positive and the black is negative? The markings on the cap are nearly impossible to read.

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RE: Electrolytic Cap 30-2409 Question - Radioroslyn - 01-17-2022

Does the "red" wire go to the cathode of the 7Y4 tube and the "black" wire go to the center tap of the hv winding of the power transformer? If so you are correct!

For those following at home it's p#57 in the 42-345 12mfd/400v input cap in the hv supply.

https://philcoradio.com/library/download/service%20info/yearbooks/1942/split/Part22-Philco%201942%20RMS%20Year%20Book.pdf

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RE: Electrolytic Cap 30-2409 Question - cdoyal - 01-17-2022

Red goes to the 7Y4 but the black goes to the same position on the 7B5.

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RE: Electrolytic Cap 30-2409 Question - Mondial - 01-17-2022

Yes that is correct. Positive of the cap (red) goes to the pin on the 7Y4 socket and negative (black) to the pin on the 7B5. This pin on the 7B5 is unused and the socket terminal is used as a tie point for the center tap and the grid bias resistor of the 7B5.

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RE: Electrolytic Cap 30-2409 Question - cdoyal - 01-17-2022

Perfect. Thanks!
I used a heat gun to melt the wax on the old cap and was able to confirm black was negative.

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