A new way to restore smoothing capacitors

[Refugee]

This can now be done without cutting the can open and in some cases could even be done with the can remaining in the chassis while you work on it.
These are the parts I shall be using.

http://golbornevintageradio.co.uk/forum/...p?tid=3756

My first trial will be on a 32uf + 32uf 450V smoothing can.
It had dried out and there was crystals where it had leaked out.
I first tried to add some distilled water and tried to reform it without success.
The bung de-laminated and the terminals corroded until the bung became conductive.
   
   
I could get 4 of them in the can side by side if it was a 4 cap can.
They are of a slim design and should fit in a 10mm hole drilled through the bung with just a little spot of epoxy to retain them.
I will not use the old terminals as these became damaged during the reforming attempt although I am tempted to use the negative as a tie point.
It does not look like there is even any need to dig out the remaining foil wind unless the original terminals are going to be used again and the bung has been tested to make sure the insulation is still good.
   
   

[Old Sparky]

This looks like a good idea, although, personally I never re-stuff old electrolytic capacitors, instead using the modern dual & triple cans made by F&T, and stocked by (amongst others) Cricklewood Electronics and 'www.askjanfirst.de'
The latter site stocks a wider range than Cricklewood, plus many other components.

[Refugee]

I have seen those.
They do tend to look a little out of place in bright blue or red.
Doing them without removal from the chassis is also attractive due to a cramped layout on the top side.

[Nick]

'www.askjanfirst.de'
The latter site stocks a wider range than Cricklewood, plus many other components.

Jan Wuesten of "Ask Jan first" is an excellent chap - dealt with him for many years, always with first class personal service. He doesn't do rubbish - only top quality - and a huge range of stuff at that.

Cricklewood are good too (before anyone complains!)

[Yorkie]

I've just taken delivery from Farnell of some of the newly stocked miniature Rubycon BXW series of miniature caps, which are ideal for stuffing multi-section can type electrolytic caps.

At first sight they look puny and not really up to the task, but they do have a high ripple rating, beyond what is needed for typical domestic valve radios. Those in the attached picture from left to right in the 'front row' are 15uF, 22uF, 33uF and 47uF. The three between the two cans are 18uF and give an indication of their small size. The small can on the left is a (NOS) 3-section 16uF which is 25mm diam x 45mm tall (1" x 1.75" in 'old money). The yellow can on the right is a (NOS) 2 section 16uF which is 35mm diam x 50mm tall. (1.5" x 2") - same size as the smoothing/reservoir cap in the DAC90A etc. As can be seen, even in the smaller can, three caps would just fit side by side, 'triangular fashion'.

I don't want to spark off a pointless debate about the merits or otherwise of stuffing old electrolytics and I know that not everyone may want to go to that trouble, especially in a commonplace set of little value, but instead, may prefer to simply disconnect the old cap and fit new ones beneath the chassis. But for anyone who does wish to stuff caps to preserve the originality of appearance of the set, these particular ones lend themselves to that role. (Those in the picture ore all 450V WKNG). As to price, they're not expensive - all fifteen came to £24.41 inc VAT and free delivery - about £1.63 each on average.

The Data Sheet is here:

http://www.rubycon.co.jp/en/catalog/...inum/e_BXW.pdf

The caps are here:

http://uk.farnell.com/jsp/search/pro...-bf9f-00001000

Hope that's of interest.

Thanks to 'Refugee' for bringing these dinky little caps to our attention!

[Refugee]

The one thing I would check carefully it that if you use the original terminals as anchor points is that the old roll of foil does not dry out and shrink falling down onto the inside of the tags to cause a short circuit.
The two methods I would use is either to dig it out through the drilled hole(s) in the bung or a spot of epoxy between the tags and the roll of foil.
I once found one that was so loose that you could shake it and hear the roll of foil rattling freely inside the can.

[Yorkie]

In the few that I've done, I've cut the can open carefully on the lathe at the base of the cap, gutted the cap, cleaned up the two mating surfaces (again on the lathe), then having stuffed the cap, I've joined the two parts together with epoxy and a sleeve. I've attaches pics of one that I recently re-stuffed for an Ekco AC77 I'm slowly restoring, which I've posted in other threads. As can be seen from the last pic, apart from the fact that the cap was duff, it was also shabby so I wanted to smarten it up a bit as well as re-stuff it. (You can see the join of course but it's no big deal, and on some caps, the join would be hidden by the fixing clip). I made and fixed a waterslide transfer with the necessary data on it.

(In this particular case the cap didn't have tags - the leads came out of the central fixing boss).

[Refugee]

That single nut mounting one is a little bit more of a challenge.
I would have looked into turning the bung out with the threaded part still attached.
Then I would then have salvaged the threaded gland and screw terminal and fitted a grommet the correct size.
Much more of a challenge without a lathe though.

[Yorkie]

The bung is Bakelite - not rubber, and the hollow mounting bolt was moulded into the Bakelite so I wanted to keep the base intact.

[Refugee]

I have seen them with Bakelite bungs before.
That would have been even more of a challenge without cutting the can.