Replacing filter caps on tube p.a

[jonniewalker]

Hi I'm abit of a newbie when it comes to electronics, I've just got feed up of being messed around. so i thought i have a go myself.  i've got Selmer PA100 SV amp that needs some love. thought i would start with the filter caps. x4 100uf 450v x2 32uf 350v x1 50+50 uf 450v. I've been looking around for parts it seem quite expense to buy nos or new cans, i've seen some people restuff the cans with modern components or fit them in the chassis, if theirs room. what would be good replacement components. would this be a good replacement for 100uf?
http://uk.farnell.com/nichicon/lgu2w101mela/cap-alu-elec-100uf-450v-snap-in/dp/8813450

Heres come the stupid questions, so the 100uf caps have 2 pins and all the others have 3 is that just ground and on the 2 pin it negative to ground? would the 50+50 uf 450v need to be made out of x2 50uf caps and how would i wire them?

Any help would be great, and by the way i know about discharging caps.

I've attached the schematic

Cheers

Jonnie

 

[musika]

Could the third connector you are seeing just be a stabilizing pin? 

I recently replaced some large caps in a power supply that were manufactured in the 70's where this was the case.  Look at the solder points on the circuit board, the third pin might just be for rigidity on the circuit board.  The newer versions of the same caps were ¼ the size of the old.

Also, the cap you showed for replacement has a socket arrangement for plug-in.  You most likely need a radial leaded capacitor.

Can you post a few photos that show those "3 lead capacitors" that you want to replace?

 

[pucho812]

hmmmmm 3 pin caps? Are the caps multi-value?

 

[qmp audio]

hmmmmm 3 pin caps? Are the caps multi-value?

I just re-capped my marshall head.  The filter caps i used where a single can with 2x 50uf in parallel:

http://www.thetubestore.com/Capacitors/F-T_2/F-T-Can-Capacitor-50uF-x-50uF-500V

 

[jonniewalker]

Hi thanks for the help guys. heres a pics, what would be good
cheap modern replacements for these caps.

Cheers

 

[jonniewalker]

Thanks

 

[jonniewalker]

blue cap

 

[PRR]

Two caps in one can with common negative used to be cheaper than two cans.

No more.

The 2-in-1 bundle does not work great where grounds are very different (first power filter with preamp, for example) or where caps are stacked (you have this).

I do not see ANY 50+50 on the schematic you posted, which suggests further study of what is really happening.

The Snap-Caps may be the best current replacement. You replace a 2-in-1 with two caps. The mounting is VERY different, and suggests a PCB (may be bare) mounted inside where fingers do not go. I do not know if the Selmer build-style encourages this. (Is a real problem on late Ampegs.)

 

[jonniewalker]

Hi, thanks for the reply. i'm still trying to get my head round this. Whats the difference between have 2 pins or 3pins? is the 100uf 450v.  Two caps in one can? i'm guessing that if it has 3 pins, its two caps in one can, were as the 100uf 450v has 2 pins so that is just one cap? if you were to replace the caps "x4 100uf 450v x2 32uf 350v x1 50+50 uf 450v" what modern replacments would you use and how would you wire them? just want to make sure i'm going to get it right.  appreciate the help.

Cheers

Jonnie