Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: pbman1953 on January 25, 2021, 04:05:38 pm

Title: Cap replacement question
Post by: pbman1953 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

Title: Re: Cap replacement question
Post by: sluckey on January 25, 2021, 04:10:50 pm

Isn't one of those 20µF caps inside a multi-cap can?

Title: Re: Cap replacement question
Post by: pbman1953 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

Title: Re: Cap replacement question
Post by: sluckey 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.

Title: Re: Cap replacement question
Post by: pbman1953 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?

Title: Re: Cap replacement question
Post by: sluckey on January 25, 2021, 04:46:16 pm

Why do you need a new filament transformer?

Title: Re: Cap replacement question
Post by: pbman1953 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

Title: Re: Cap replacement question
Post by: thetragichero 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?

Title: Re: Cap replacement question
Post by: pbman1953 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.

Title: Re: Cap replacement question
Post by: pbman1953 on January 25, 2021, 07:21:11 pm

Quote from: pbman1953 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

Title: Re: Cap replacement question
Post by: sluckey on January 25, 2021, 07:22:14 pm

Try it and see.

Title: Re: Cap replacement question
Post by: pbman1953 on January 25, 2021, 07:23:45 pm

Quote from: sluckey on January 25, 2021, 07:22:14 pm

Try it and see.

Will do! Thanks