Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Mars-Hall on September 25, 2011, 12:06:56 am

Title: Cap substitution
Post by: Mars-Hall on September 25, 2011, 12:06:56 am

My SFSR has aa electrolytic 5uf 25v cap that comes off one leg of the optoisolator in the tremelo circuit.  Would it be ok to substitute it with the 4.7uf 50v cap that Doug offers?  Is it critical to even replace that cap?  Mouser offers the correct value but I have other stuff to order and would like to give all the business I can to Doug.  The tube amp library is the best thing in the world and want to do all I can to support it.
:worthy1:

Title: Re: Cap substitution
Post by: DummyLoad on September 25, 2011, 12:17:18 am

Would it be ok to substitute it with the 4.7uf 50v cap that Doug offers?

absolutely! it will work just fine.

if you have to replace some of the electrolytic caps, then you should replace all of them. even tough that cap sees light duty, electrolytic caps dry up over time and fail shorted.

--DL

Title: Re: Cap substitution
Post by: Mars-Hall on September 25, 2011, 12:31:55 am

Thanks!  The amp still sounds good as is, but being nearly 40 years old with all original caps, I'm trying to get ahead of any failures. 

Title: Re: Cap substitution
Post by: stratele52 on September 25, 2011, 04:41:21 am

4.7 or 5 Mfd = the same

Title: Re: Cap substitution
Post by: bigsbybender on September 25, 2011, 12:48:37 pm

Quote from: stratele52 on September 25, 2011, 04:41:21 am

4.7 or 5 Mfd = the same

Exactly

Consider that most common caps of that size are rated at + or - 20%  4.7uF is well within the spec.