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112RP-65, GP-1, C-23 polorization?

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Mike H
Posted on Saturday, June 18, 2005 - 06:51 am:   

My amp does not have an original Mallory cap at C23. It has an apparent replacement Sprague Atom (TVAN) 10uf 35v non polorized cap. I do not see a positive side indicated on the schematic. So:

1. Was C-23 originally non-polorized?
2. If not, which direction is positive? Toward the back of the amp or front? C-23 is across 6 & 7 of IC-6 (LM1458).
3. Sould this cap be a 25v like most of the others? Or, is 35v correct? Or, maybe a 50V???

I'm getting ready to replace all the caps and would like to get it right. Thanks.
Steve Kennedy (admin)
Posted on Saturday, June 18, 2005 - 04:24 pm:   

It appears (from the schematic) that C23 is indeed a non-polar electrolytic. These can be acquired from anyplace that sells components for making speaker crossovers and is a common value (just harder to find than polarized parts).

You can also "make" one by taking two 20�F polarized electrolytics and putting them in series "back-to-back". This means connecting to the two negatives together and the two positives go to your circuit points. Just mount them in "tee-pee" fashion (inverted "V") on the board.

Steve

Mike H
Posted on Sunday, June 19, 2005 - 11:31 am:   

Thanks!
Mike H
Posted on Monday, June 20, 2005 - 06:51 am:   

I was looking at some of the pics posted on this site of other amps like mine. In one of the photos, it appears that C23 is the same as on mine. So, I now suspect that MM used a Sprague Atom (TVAN) 10uf 25v cap possibly because it's the only one in the amp that is non-polorized?