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Hoffman Amps Forum image Author Topic: Cap replacement question  (Read 2580 times)

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Offline pbman1953

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Cap replacement question
« on: January 25, 2021, 04:05:38 pm »
I was installing my new filament transformer in my 2000s and by accident a cap was damaged.


Seems to be the "C" connection that has a pair of 20uf's at 450V. I have a new 80uf at 500v. Is it too large a value or simply overkill and use it since I have it?


Thanks

Offline sluckey

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Re: Cap replacement question
« Reply #1 on: January 25, 2021, 04:10:50 pm »
Isn't one of those 20µF caps inside a multi-cap can?
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline pbman1953

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Re: Cap replacement question
« Reply #2 on: January 25, 2021, 04:12:57 pm »
Sorry I didn't mention , this has had a cap job years ago and it's all discrete

Offline sluckey

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Re: Cap replacement question
« Reply #3 on: January 25, 2021, 04:36:51 pm »
I'd use it to replace both of the parallel 20s. Might even be an improvement in a Bass amp.
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline pbman1953

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Re: Cap replacement question
« Reply #4 on: January 25, 2021, 04:42:14 pm »
So you're saying I have  a green light for the 80uf?


Also , should I check the bias?

Offline sluckey

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Re: Cap replacement question
« Reply #5 on: January 25, 2021, 04:46:16 pm »
Why do you need a new filament transformer?
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline pbman1953

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Re: Cap replacement question
« Reply #6 on: January 25, 2021, 04:48:55 pm »
For the Kt120's, to be safe. I got a 6.3 @ 10amp


Also is there any advantage to up the value for the "B" line? I have another 80uf

Offline thetragichero

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Re: Cap replacement question
« Reply #7 on: January 25, 2021, 05:00:32 pm »
any reason you're switching to kt120s? is it just because 120 is bigger than 88/60 is bigger than 42? will those transformers have enough current capability (b+ and output) to make the switch worthwhile?

Offline pbman1953

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Re: Cap replacement question
« Reply #8 on: January 25, 2021, 05:04:20 pm »
For me they are so worthwhile, blame Ed Chambley, in good way. For me nothing beats them. I wanted to help the amp , based on Ed's and a high end tech that used to work for Ampeg to install the FT.

Offline pbman1953

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Re: Cap replacement question
« Reply #9 on: January 25, 2021, 07:21:11 pm »
For the Kt120's, to be safe. I got a 6.3 @ 10amp


Also is there any advantage to up the value for the "B" line? I have another 80uf

Offline sluckey

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Re: Cap replacement question
« Reply #10 on: January 25, 2021, 07:22:14 pm »
Try it and see.
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline pbman1953

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Re: Cap replacement question
« Reply #11 on: January 25, 2021, 07:23:45 pm »

 


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