Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: pbman1953 on January 07, 2011, 10:03:51 am

Title: Filter cap replacement values
Post by: pbman1953 on January 07, 2011, 10:03:51 am

For this amp- A Traynor YBA 3 Custom-

http://www.0rigami.com/vb/YBA3__cool-schematics.gif

What would be the value suggestions to replace the 2- 40/40  filter can caps?

I had 2- 100 MF's @ 450V so I replaced the 2- stand alone units already. The ones I replaced were the 2 @ 80mf.  My next step would to either get 2 new 50/50 cans or go discrete and new resistors. I'd have the room if I took the 100's and mounted them on the main board

Thanks

Title: Re: Filter cap replacement values
Post by: JayB on January 07, 2011, 10:29:24 am

Quote from: pbman1953 on January 07, 2011, 10:03:51 am

For this amp- A Traynor YBA 3 Custom-

http://www.0rigami.com/vb/YBA3__cool-schematics.gif

What would be the value suggestions to replace the 2- 40/40  filter can caps?

I had 2- 100 MF's @ 450V so I replaced the 2- stand alone units already. The ones I replaced were the 2 @ 80mf.  My next step would to either get 2 new 50/50 cans or go discrete and new resistors. I'd have the room if I took the 100's and mounted them on the main board

Thanks

50/50 will work just fine. That will bring you a total 50uf for your plates and screens. Only 10uf more. I don't know how the layout of that amp is but you could use 2 100/100uf 450v cans to end up the same way. Hard to find caps rated higher than 500V. Would be nice to find something like 600V.

Title: Re: Filter cap replacement values
Post by: pbman1953 on January 07, 2011, 10:36:46 am

Here's waht I found for the 50/50-

https://taweber.powweb.com/store/dcan.jpg

They have both 50/50 & 100/100

But wouldn't be better to use individual caps? I think I have the room

Thanks

Title: Re: Filter cap replacement values
Post by: JayB on January 08, 2011, 11:14:42 am

Either way will work. It's just a matter what is easy for you and keeping it some what period correct or stock.

Title: Re: Filter cap replacement values
Post by: PRR on January 08, 2011, 03:05:12 pm

> replace the 2- 40/40  filter can caps?

Pete used the 40+40 can-cap because, in 1967, it was cheaper than a 80uFd.

He had to use an insulated 80uFd for the upper cap in each stack.

It's like my old foundation. A row of rocks, then a row of bricks. Yes, everything is strong and hard and it holds-up the house. But lots of minor settling and cracking because of the different components.

What they did at the factory to meet contract and payroll is not what might be "best". The mix of 40s and 80s should be four identical caps, at least 80uFd, at least 350V.

The driver feeder C29 will rise above 450V at start-up or in standby; this should be 500V rating. (If you buy a ten-pack of 100uFd 350V, you can use four 100u 350V caps here.)

I do not recall how the inside of a YBA3 look, if a bunch of compact axials or a PCB of snap-caps is an appropriate fit.

Title: Re: Filter cap replacement values
Post by: pbman1953 on January 12, 2011, 03:50:32 pm

I ended up to buy 2 - F&T can caps at 50/50 @ 500V and 2-F&T polarized caps 100 @ 450