Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Erik Aa on March 06, 2022, 05:46:12 am

Title: Replacing electrolytic cap cans
Post by: Erik Aa on March 06, 2022, 05:46:12 am: Hi. I have two stacked electrolytic cap cans that need replacement. One 16uF + 16uF 500v/650v, and one 50uF + 50uF 450v/500v.

Here is my question. Is it ok to put in one 16uF + 16uF 500v/500v, and one 50uF + 50uF 500v/500v instead?

Any opinion and/or advice on this would be highly appreciated.

Thanks!
Title: Re: Replacing electrolytic cap cans
Post by: bmccowan on March 06, 2022, 07:28:20 am: definitely yes on the 50/50, and maybe on the 16/16. But what is the amp? You need to determine if a 650v rating is really needed?
Title: Re: Replacing electrolytic cap cans
Post by: Erik Aa on March 06, 2022, 07:51:24 am: Thanks. The amp is a EKO made in Italy. Two 12ax7 and two el84. I have seen a schematic for a very similar EKO amp and that one has 500v on the 16/16 uF.
Title: Re: Replacing electrolytic cap cans
Post by: sluckey on March 06, 2022, 08:05:09 am: 500V seems excessive for EL84s. I suggest you measure the voltages in your amp BEFORE ordering and replacing caps.
Title: Re: Replacing electrolytic cap cans
Post by: Erik Aa on March 06, 2022, 08:33:25 am: I believe the amp is from around 1965 and the caps have leaked electrolytic and don’t hold voltage well. They measure around 260 volts when the amp is powered up. The aforementioned schematic for a similar EKO amp has 500 volts for the 50/50. So am I in the clear? Regards.
Title: Re: Replacing electrolytic cap cans
Post by: acheld on March 06, 2022, 10:03:11 am: You should be ok with 500V ratings on those cap cans.

I'm basing that on your posted voltages, though the caveat is that we don't know the model of the amp, have no schematic, don't really know where those voltages are taken, don't know if the leaking cap cans are original -- there's a lot here we know we don't know. That said, none of the EL84 amps (all Blues Juniors or heavily modded BJs) I have require more than 500V ratings on their filter caps.
Title: Re: Replacing electrolytic cap cans
Post by: Erik Aa on March 06, 2022, 10:17:42 am: Thanks. Here is an image of the original caps. I will try to upload an image of the similar schematic later.