Stupid question about FP can caps

[Noval_novice]

I am trying to restore a 1946 Oahu that has a single Sprague FP can cap. I am a total noob and have not used these before. I have a replacement can cap in hand but was a little confused about the connections. I know the interior lugs are the positive ends of the caps, but I want to ask a question about the external lugs. These are the negative (ground) ends, correct? There are three separate external (ground) lugs on my new cap but only 2 caps in the can. Are all three connected and equivalent?

[ampdoc1]

Probably!! Use your ohm-meter to check.

[KT66]

One of the "interior" lugs is the common ground for both caps. If you look closely at them there should be a mark or some way to distinguish between the 2. The exterior ones are not connected to the cap ground.

[M Fowler]

Here is drawing showing outer are for ground. The cap should be marked as for the positve connections.

[KT66]

Mark is right of course, I had a brain fart because I misread the question The can is the common ground connection and all the tabs that are a part of it are as well. Sorry for the misinformation.

Btw, those caps are expensive so I usually just clip them out of the circuit and put regular electrolytics inside the chassis if they will fit.

[tubeswell]

Furthermore - all the ground tabs in a cap can are common, so one ground to one of those caps will ground all the caps in the can (which is why cap cans are not ideal for filtering - better results are obtainable with separate caps)

[Noval_novice]

Thanks, guys! That's what I thought, but I hadn't dealt with them before. And I do realize they are not ideal in terms of grounding, noise, but I'm trying to keep this ugly amp 'period correct.' I don't think I would use them again.

[renshen1957]

I am trying to restore a 1946 Oahu that has a single Sprague FP can cap. I am a total noob and have not used these before. I have a replacement can cap in hand but was a little confused about the connections. I know the interior lugs are the positive ends of the caps, but I want to ask a question about the external lugs. These are the negative (ground) ends, correct? There are three separate external (ground) lugs on my new cap but only 2 caps in the can. Are all three connected and equivalent?

Hi

Check out Antique Radio Supply (or if you are a busines their wholesale division CE distributors) or Weber for Can Caps.

Best Regards,

Steve

PS Ditto, as to the noisy aspect of multi-cap cans.