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 Post subject: Re: Forming filter caps
PostPosted: Sat Apr 24, 2010 10:10 am 
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Roe wrote:
after about 12 hours the sprague atoms in a fender have not dropped below 38volt. and these caps are pretty new. I guess I'll have to change them


You did remove the 220K bleeder resistors didn't you?

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 Post subject: Re: Forming filter caps
PostPosted: Sat Apr 24, 2010 10:51 am 
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flemingmras wrote:
Roe wrote:
after about 12 hours the sprague atoms in a fender have not dropped below 38volt. and these caps are pretty new. I guess I'll have to change them


You did remove the 220K bleeder resistors didn't you?


yes but someone had installed an extra 1m somewhere :evil:

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 Post subject: Re: Forming filter caps
PostPosted: Sat Apr 24, 2010 11:12 am 
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Roe wrote:
flemingmras wrote:
Roe wrote:
after about 12 hours the sprague atoms in a fender have not dropped below 38volt. and these caps are pretty new. I guess I'll have to change them


You did remove the 220K bleeder resistors didn't you?


yes but someone had installed an extra 1m somewhere :evil:


But at least it got ya lookin'...and ya found it. ;)

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 Post subject: Re: Forming filter caps
PostPosted: Fri May 07, 2010 11:59 pm 
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Will this work? I too like pictures (duhwing :? )

On #3, should I lift the entire rectifier wire that bridges the two + terminals and connect the 100k/1w to just the first +? Then there would be nothing connecting the two + terminals.

I guess same question for the 56k bleeder resistors. Do both + terminals need to stay connected? Sorry, I'm a newbie late to this. Many thanks!
Image

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 Post subject: Re: Forming filter caps
PostPosted: Sat May 08, 2010 10:10 am 
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yes, the terminals need to stay together. just unsoldier one end of the 56Ks. and use one leg of the 100k to bridge the terminals on #3

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 Post subject: Re: Forming filter caps
PostPosted: Sat May 08, 2010 2:28 pm 
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That's great, thanks Roe. :D

It's funny, I can make a nice and pretty graphic of it, but don't completely understand it at the same time. :oops:

Man, I really appreciate this forum as a mix of players and techs, best of both worlds.

And the fact that folks here who are heavy in the knowledge (and there are a lot of 'em) take the time to help those who are tech challenged to learn some along the way, and not kill themselves!! :shock:

Truly excellent. Rock on.

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 Post subject: Re: Forming filter caps
PostPosted: Fri Jun 18, 2010 8:12 am 
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how about detaild instruction on how to do this with a 12 series with the cap board inside?? The diode wire goes from the diodes to the HT fuse holder. Is that where the 100k res goes?? Thanks Mark

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 Post subject: Re: Forming filter caps
PostPosted: Wed Jul 07, 2010 3:13 pm 
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Ok so al little over a year after my initial question I finlly had my build to a stage to where I could try this. I'm not sure about the result though. I let the amp sit for 24h. After about 13h it was down to about 8V but never went lower after 23-24h it went up to 9V again.

Not sure if I should change the caps or not? They are brand new J/J caps.

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 Post subject: Re: Forming filter caps
PostPosted: Thu Jul 08, 2010 2:19 am 
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Ok so according to what Larry said earlier if the voltage does not drop below 5V the caps are questionable. To test this I replace the J/Js with the blue F&Ts that I normally use. And guess what. 9h later and down to 3,8V. WTF? What's up with the J/Js?

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 Post subject: Re: Forming filter caps
PostPosted: Thu Jul 29, 2010 10:15 pm 
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F&T caps are the best. i got them with my amp instead of the JJ's, im sorry but i hear nothing but bad things about them. i got some bad el34's from them once and my mind is made up. cant be thrifty with certain parts. IMHO.

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 Post subject: Re: Forming filter caps
PostPosted: Fri Aug 20, 2010 1:09 am 
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Hi, i have a question about reforming. After just reading the instructions i don't understand if it's enough to measure the voltage drop just across the first filter cap or i should repeat the measure for every filter cap in the circuit. Because if for example the PI filter cap needs to be changed how can i know it just measuring the voltage drops on the first filter cap?


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 Post subject: Re: Forming filter caps
PostPosted: Sat Aug 21, 2010 6:05 am 
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If at the end i'm only able to reach 10V instead of 5V or lower, how is about my filter caps? should i changed because 10V is really bad, or could i play with the amp fine anyway?

I mean: is there much difference if i get stuck on 10V or if i reach 5V?


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 Post subject: Re: Forming filter caps
PostPosted: Mon Aug 23, 2010 6:38 am 
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measure across the 100k resistor, not the cap.
10v means its ok
5v means good
2v means great

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 Post subject: Re: Forming filter caps
PostPosted: Mon Aug 23, 2010 7:49 am 
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yes, i switched them off yesterday, because they were stuck at 8V (one is a jmp 2203 from '78 and the other is a jmp 1959 from '79).

Today i will listen if there are any differences.

By the way i'm waiting for 15 new ARS 50+50uF caps to replace these dalys if they will need (and i think that they need!)


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 Post subject: Re: Forming filter caps
PostPosted: Mon Aug 23, 2010 9:20 am 
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marci84 wrote:
By the way i'm waiting for 15 new ARS 50+50uF caps to replace these dalys if they will need (and i think that they need!)

I wouldn't swap orig. Daly's, as long as they reach less than 10V across the 100K resistor by forming within a 24h forming process. The ARS's won't give you the sound of Daly's, LCR's or Erie's.

Larry

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