2. tech-talk
  3. 169140-5759

Electrolytic capacitor replacement

I want to swap out a couple of electrolytic caps with higher quality caps, also electrolytic. The ones I am looking at are all physically bigger than the ones I am replacing, and consequently the leads don’t fit the board. The rubicon’s I want to bin are have a diameter of around 3/4’ and the caps I’m considering are between 1’ and 2’. The big issue I have is the lead spacing.

I’m considering using a spacer between the pc board and the cap giving enough room for the leads to bend enough to fit the board. I have space on the board to fit a larger cap, but not enough to mount the caps on their side. The caps new will need to sit “upright”.

Id appreciate it if somebody has figured an eloquent solution for this.

Thanks
pauly
pauly OP
1,012 posts
 
Are you using the Audio Note KAISEI caps? Great caps!


I’m looking into kaisei caps - the value I’ll need to get has snap on connectors -> 50uF/500v. They have a 50uF/350v with leads but I’m uncomfortable going down to 350v given the board specifies 47uF/400. The actual caps are 47uF/450v so …

I was also looking into Mundorf MTubes, but if anything they’ll be more challenging to mount than the kaisei. 
I was also thinking of drilling holes in the PC board that match the cap spacing and the routing the leads to the existing holes underneath the board. I’d need to glue the caps in place with some non conductive epoxy. 
I’ll look into Soundcoat . Never heard of it before.


grannyring's avatar
grannyring
6,464 posts
 
Careful drilling holes if the board is double sided etc…! Also, sometimes a ground plane is located close to the solder pads. You could cause a short.  Soundcoat is sold at Parts Connextion and Sonic Craft I think. Sonic Craft used to sell it. I use the stuff all the time in my mods/upgrades.
pauly OP
1,012 posts
 
@grannyring 

Have you used glue on PC boards before? I'm worried an epoxy may be too much and you end up with a hole in the board when you want to change later on. A friend of mine used a glue gun but that is way to much heat for my liking. 
grannyring's avatar
grannyring
6,464 posts
 
No need. If you solder the leads properly from under the board, then you can tension the leads strong enough so the cap rests securely on top of the precisely cut Soundcoat pads. This is all you need.

If you don’t want to do that, then hot glue always works and comes off fairly easily without damaging the board should you need to remove the cap. I don’t like using any kind of goop for this sort of thing, but that’s me.

You could also use double sided tape pads in place of the Soundcoat material.
pauly OP
1,012 posts
 
@grannyring 

I’ve taken a peek inside my 2A3 monos, and over there I have all the space in the world for cathode bypass caps. I was wondering if you have tried Solen PB caps for cathode bypass? 
I’m thinking they’re film, which beats an electrolytic all day long, and they’re very inexpensive. Size is not a problem. 
More to discover