Forming filter caps

axeman · Post by **axeman** » Tue Jan 06, 2009 11:20 pm

novosibir wrote:
axeman wrote:Are you saying to place a resistor between the red wire and the filter (main filter)?
The Resistor then is located between the rectifier and the first filter caps - temporarily, until forming is done.

Larry

Larry does this look rite. I removed one lead from the 56k resistors, added a 100k resistor between the first main filter and the red wire going to the rectifiers. I disconnected the yellow wire from the second main filter. My amp has been on for 1 hour and it reads 476 volts the voltage goes up not down.

budubum · Post by **budubum** » Wed Jan 07, 2009 3:39 am

axeman wrote:
novosibir wrote:
axeman wrote:Are you saying to place a resistor between the red wire and the filter (main filter)?
The Resistor then is located between the rectifier and the first filter caps - temporarily, until forming is done.

Larry
Larry does this look rite. I removed one lead from the 56k resistors, added a 100k resistor between the first main filter and the red wire going to the rectifiers. I disconnected the yellow wire from the second main filter. My amp has been on for 1 hour and it reads 476 volts the voltage goes up not down.

i dont know if you are still doing thins but i think you should stop and changeout that resistor to a bigger wattage. he said something on the prev. pages i cant remember right now.

but you didnt see or noticed any smoke or heat right?

budubum · Post by **budubum** » Wed Jan 07, 2009 3:42 am

EDIT!

i appologize for beinga big mouth. i read the statement where it clearly stated 100k/1watt.

sorry for the missunderstanding. thouught of very high voltage. better safe than dangerous right?

novosibir · Post by **novosibir** » Wed Jan 07, 2009 9:10 am

axeman wrote:Larry does this look rite. I removed one lead from the 56k resistors, added a 100k resistor between the first main filter and the red wire going to the rectifiers.

Rite? Yes, right!

axeman wrote:I disconnected the yellow wire from the second main filter.

Electronically regarded it's between the 1-st filter group.

axeman wrote:My amp has been on for 1 hour and it reads 476 volts the voltage goes up not down.

Where are you measuring? From the diodes to ground?

Read my instruction once again!

Measure the voltage drop ACROSS the temporarily installed 100K resistor!

This means: Clip one meter lead BEFORE, the other AFTER the 100K - this means ACROSS!

Larry

Warning: If anybody can't read instructions, or doesn't understand my instruction about forming caps absolutely 100% and/or after reading it isn't shure absolutely 100% about that, what he's supposed to do in the amp - then he/she better shouldt give the amp to an experienced amp tech to have him doing this! Always keep in mind: Inside the amp occur lethal voltages, which might kill you, if you're doing ONLY ONE MISTAKE !!! And the voltage doesn't care about, whether the mistake has happened due to accident or due to misunderstanding!

budubum · Post by **budubum** » Wed Jan 07, 2009 9:17 am

when you say ACROSS then i gotcha. black lead on 1st leg of resistor and red lead on the other leg of the 100k.

it sometimes confusing novosibir sometimes ppl say across then what they actual meant was something else. but this one is clear to me now. hope this is clear for everyone stopping by here

axeman · Post by **axeman** » Wed Jan 07, 2009 9:59 am

Thanks Larry, it's all clear now. You set me free.

budubum · Post by **budubum** » Wed Jan 07, 2009 10:35 am

axeman wrote:Thanks Larry, it's all cleare now. You set me free.

how is it going? did it worked what larry said? oltage and such?

axeman · Post by **axeman** » Wed Jan 07, 2009 10:46 am

Yes, It's working great. The voltage at this time is reading 9.08v and the amp has been on for 15 minutes now. These caps are the CE caps.

novosibir · Post by **novosibir** » Wed Jan 07, 2009 11:01 am

New caps are forming quickly and you'll probably come below 5V voltage drop after 2-3 additional hours - maybe even down to residual 2-3V, depending on the cap's quality. A cap, what has been stored unused for 5 years or longer will take much more time, until it reaches a low leakage current (what you're measuring with the voltage drop method across the resistor).

My NOS LCR's from 1993 usually take 8-12 hours of forming, to go below 5V - and additional 10-14 hours, to go below 2 volts.

Larry

axeman · Post by **axeman** » Wed Jan 07, 2009 11:05 am

Got it. Thanks larry.

I'm going to see if I can figure out the samething for my 68 and ceriatone 45/100.

axeman · Post by **axeman** » Wed Jan 07, 2009 6:39 pm

8 Hours now and olny 1 volt drop. I have my Meter set on DC and it read -7.46

fatcatefx · Post by **fatcatefx** » Sat Jan 31, 2009 1:47 pm

GRRREEEAAAT! Did this to my 1987 -- really makes the tone smooth! Great way of forming, and alot cheaper than a variac! Thanks Larry

5150loveeddie · Post by **5150loveeddie** » Fri Mar 13, 2009 9:57 pm

Larry, when you say disconnect one lead for both 56k bleed resistors, what do you mean? Which lead do I need to disconnect there?

Thx Larry!!

novosibir · Post by **novosibir** » Fri Mar 13, 2009 10:44 pm

Every resistor does have two leads - or two terminals - and you always have to connect both leads, that a current can flow through the resistor at all. When you now disconnect only one lead of the both, the current flow stops immediately...

... but the current doesn't care about, which of the both resistor leads you've disconnected

If you're still in doubt, then remove both resistors entirely and put it back in place, after you've done.

Larry

Roadrunner · Post by **Roadrunner** » Sun Mar 15, 2009 12:33 am

Hi Larry...

I just want to say that this method absolutely works... perfectly!

The last few amps that I've made for customers have had the caps formed using your method and they sound... perfect, after this process.

Thanks for sharing this information!!

Gary

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