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Old 26th September 2009, 03:52 PM   #1
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Default FISHER - 500b Caps Leave Them In ???

Hello,
So I got this Fisher 500b off ebay last year. It had one channel not talking.
I was hoping for an easy tube swap fix. But that's not the way it worked out.
I wound up replacing the multi-part condensor attached to the treble pot..

I did rebuild the B+ power supply sections now my finals aren't frying.

Last night I replaced 2 stock caps in the tone control amp section. C14 and C15 with 2 sprague Orange Drops. .022uf/600v...
Powerd it back up and immediately noticed the audio sounds crappy. I was amazed. I was going to put the old ones back in but I clipped those right up to the point where they couldn't be used again. It was late, I was tired and a little pissy. This morning I get up and turn it on and was surprised again. A drastic difference. Now hearing things I wasn't before, for the better. Last night it was like the mids kinda rolled off into a little grainy sound. now I'm thinking I was hearing things.

Anyway, the main question here. I have more of these to replace in the amplifier section but wonder if I should. What is the problem with leaving the old stock ones in there?
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Old 27th September 2009, 11:02 PM   #2
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The prob with old stock ones is they have drifted out of spec in most cases and may leak in some cases as well. As for the changes in sound thats the caps burning in. I wouldn't pass judgement until the new caps burn in which is minimum 10 hours playing time. There will be many that disagree with cap burn in but I am a firm believer. A full recap would benefit you immensely and get the amp ready for the next 25 years. The only other danger is if a cap pops and put a bunch of wax and oil all over the inside of the chassis which is a big mess to clean. If your unit has matched pairs of bias resistors I would replace them that is almost mandatory. Look for the asterisk next to a pair of resistors and those are the matched pairs. Just my opinion. Hope that helps.
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