I've got a radio and need to replace the filter caps. The schematic says there are 3 of them. A 20,25, and 30. In the radio there are two 40's and a 20. Do you go by the print or who's right? By the way the rectifier tube had a short, would too large a cap cause this. John

:I've got a radio and need to replace the filter caps. The schematic says there are 3 of them. A 20,25, and 30. In the radio there are two 40's and a 20. Do you go by the print or who's right? By the way the rectifier tube had a short, would too large a cap cause this. John

John,
It would help if you posted the make and model of the radio.
Carl T

It's a Philco mod. 53-562. John

::I've got a radio and need to replace the filter caps. The schematic says there are 3 of them. A 20,25, and 30. In the radio there are two 40's and a 20. Do you go by the print or who's right? By the way the rectifier tube had a short, would too large a cap cause this. John
:
:John,
:It would help if you posted the make and model of the radio.
:Carl T

:It's a Philco mod. 53-562. John

John:
On a radio like that, the caps are not too terribly critical. Either of the values you mentioned would work well. I would go with the schematic. A too large value cap (within reason) will not harm a rectifier tube, but a shorted rectifer tube will for sure ruin a cap.
Lewis

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:::I've got a radio and need to replace the filter caps. The schematic says there are 3 of them. A 20,25, and 30. In the radio there are two 40's and a 20. Do you go by the print or who's right? By the way the rectifier tube had a short, would too large a cap cause this. John
::
::John,
::It would help if you posted the make and model of the radio.
::Carl T

As Lewis said, caps on that radio aren't too critical. Many of those radios simply have a 50 right at the rectifier, and a 30 after the filter resistor. With a 50, it is rare to see the rectifier arc over at that voltage (120). With your filter arrangement, such high electrolytic values aren't as necessary. The output plate voltage is taken after a resistor, which smooths the ripple (the resistor actually reduces the load on the first electrolytic, so that it can maintain a fuller charge). If you want, start with the values listed in the schematic. If you aren't satisfied, increase the first two to 50 (47 in to-day's terms), and the third to 30.

You should be fine with the original values.

T.