[carl1124]

The Main filter cap. on my very old Philco needs to be over hauled. The problem is what caps do I use. I seen a YouTube video and the guy used big Metalized Polypropylene Film number 155K/630 as with the other I am sure they where 205K630V. I would think you should use Electrolytic Capacitors. I link the video at the bottom and here is the layout of the capacitors as shown in the schematic. So my question is, did he do this right and can someone tell me for sure how to rebuild the this capacitor? I have done capacitor rebuild before but this is the first big like this. https://www.youtube.com/watch?v=BB956EnTjBg&t=211s

[klondike98]

Welcome to the Phorum!!


The capacitance values of those caps in the main filter block are relatively small ( 2uF range) and there are film capacitors with those values that you can use. They do not need to be electrolytic capacitors. In fact my understanding is that film caps are better in this application than electrolytic. I think it is due to the size of ripple current in the circuit but one of our more knowledgeable members can comment on that.

Here’s the schematic

http://www.nostalgiaair.org/pagesbymodel...013838.pdf

[morzh]

Use film caps. Electrolytics of 2uF value are so small you will be hard pressed to find those that can work well with ripple that is required. They will work but won't last forever. The film ones will.

[klondike98]

Thx Mike. I thought that was the reason but wasn’t sure.

[carl1124]

Thank you everyone

[radiorich]

hello Carl,
yes I just got done building a reproduction of the 3 section main filter capacitor of my Zenith model 908 .
I used metal film capacitors rated at 630 volts DC .
One of the capacitors was 2.2 ufd at 630 volts DC

Sincerely Rich
P.S. those new capacitors will out live the radio that how good they are not like Electrolytic capacitor but when the value get high the film capacitors are physically to big.