What value is this Capacitor? - diyAudio
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Old 25th May 2012, 10:26 PM   #1
Jclay85 is offline Jclay85  United States
diyAudio Member
Join Date: May 2012
Default What value is this Capacitor?

Hi all, I just picked up an old National Westwood amp.

Click the image to open in full size.

Opened it up and noticed a little leakage from one of the caps. I want to go ahead and replace it but I'm having a hard time finding one of the same value. It looks like a 50v 35mfd. Might I be reading this wrong and it's actually a 5.0 volt? Is there any way to test its capacitance?

Thanks for any advice!
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Old 25th May 2012, 11:45 PM   #2
Enzo is offline Enzo  United States
diyAudio Member
Join Date: Sep 2004
Location: Lansing, Michigan
The4 value of any electrolytic cap in a guitar amp is not going to be critical.

That is 35uf and 50v. In the old days you would see MFD for microfarad. The greek letter mu in lower case is that symbol that looks like a "u". We now use that instead of M.

35 is not a standard value, so look for similar value in the standard number sequence. 33uf perhaps. 50v is a common rating, but if your supplier doesn;t have 33uf in 50v, look in 63v.

Do you know what this cap does in the circuit? If it is some sort of filter cap, 47uf would be fine, and more common than 33uf. And even if it is a cathode bypass cap, the difference between 35uf and 47uf is not much.
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Old 26th May 2012, 02:32 AM   #3
Jclay85 is offline Jclay85  United States
diyAudio Member
Join Date: May 2012
Really appreciate the info man. Ended up finding a 33uf @ 50v. I believe it's just a coupling cap. Went ahead and got new filter caps as well so hopefully she'll be singing nice and clean. There's a good chance I'll be back shortly as I dig in to this project some more. Definitely appreciative of the help'
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