Hi all,
Whilst restoring one of my television sets I found that the main smoothing can had failed so thought I would show you how I re-stuff these multi capacitor cans, please note that this is 'my way' of doing the job and not necessarily the right or best way but it seems to work and looks OK when the capacitor is placed back in a chassis. The info below may help someone who has never undertaken this task before or you may know of a better way to do the job, any comments welcome.
So we start with a 100uf / 200uf capacitor that has failed reading less than 4uf on either part.
First job is to cut the capacitor into two pieces, the cut position can vary depending on where the clamp is positioned that holds the capacitor to the chassis, in this case around 30mm from the terminal end.
Job done.
Next the Cap pieces are heated up with a hot air gun to melt the pitch inside and allow the innards of the capacitor to be withdrawn using a pair of snipe nosed pliers. When doing the terminal end of the cap it will be necessary to twist the innards to break the wires away between the dialectric and the terminals.
Capacitor shell now empty.
The terminal end of the can is cleaned with the aid of a small screwdriver and knife for scraping and a quick wash and dry.
I now drill small holes through each terminal rivet keeping close to the terminal itself.
Wire is now passed inside the can though the holes and a few millimetres are wrapped around the bottom of the terminal and soldered.
We now have leads within the can to connect to our 'new' capacitors.
A 220uf capacitor is soldered to the Yellow +ve and white common -ve, 100uf capacitor is soldered to Pink +ve and also common White for -ve. I also slid some shrinkwrap over the terminals.
Once the soldering was complete I added a support (cable ties and a piece of cut down kebab skewer) for the capacitors to hold on to.
The other part of the can is now slid over the new caps.
And the join is taped together using 'Scotch' aluminium tape.
Scotch aluminium tape.
Now the complete re-stuffed capacitor is returned to it's chassis and clipped back into place and it's leads re-soldered. Who would know....apart from me, Oh and all of you that read this !
As I said at the start this is only my idea of how to do a capacitor re-stuff but it may help someone out there. Hope I haven't bored you all to much and for those I have..... I hope you enjoyed your little nap. 
Marc.
Hi Marc,
Alternatively you could have put a request in for a replacement, I have a sealed NOS 1991. 
But seriously where's the fun in that?
We would have missed out on your useful and detailed thread and there isn't a thread on here detailing a procedure. So well done for stepping up to the plate and offering your experiences. I'm sure it will help others who have not yet considered how to go about stuffing.
As you rightly say there are likely many ways so it would be good if other 'stuffers' offered up their techniques in this thread.
Looking at the repaired cap it looks original. The original connections inside the capacitor appear to be only connecting by pressure to the old insides, I never had one to pieces before but 50 years ago we were in the position to get a new one off the shelf.
edit, not had one in piece before apart from cleaning up after the the ones that burst with a bang.
Hi Chris,
I've done quite a few 're-stuffs' over the years and have meant to show the forum how I did them but just never seem to have got round to it....until today. I'd love to know how others tackle this job. 
Hi Frank,
No, the original cap is 'hard wired' to the terminals but they snap off as the old innards are twisted out.
I was going to say it must have been nice back in the good old days to go to the stores and grab spare parts straight from the shelf, but if your at Chris's fine establishment that still seems pretty normal today ! 
Marc.
I like that way of doing it because when the cap is back in situ, you cannot tell it has been apart.
Excellent! That's really useful Marc, I'm glad you took the trouble to do this thread. I know you explained the procedure to me when you were last here, but as they always say, pictures speak a thousand words.
Steve
I always used to pull out the rubber end and then use melted wax to pour in over the new caps inside almost to the top and then use araldite glue to seal it off and hold the new connection tags in place.
In future, I will adopt Marc's method as it is less messy and less of a performance. Not only that, the can may be opened up again if one of the new caps ever need to be replaced.
colourstar said
Excellent! That's really useful Marc, I'm glad you took the trouble to do this thread. I know you explained the procedure to me when you were last here, but as they always say, pictures speak a thousand words.Steve
Hi Steve,
I'd forgotten your interest in how to re-stuff cans, I'm pleased this post helps you.
Marc.
PYE625 said
In future, I will adopt Marc's method as it is less messy and less of a performance. Not only that, the can may be opened up again if one of the new caps ever need to be replaced.
You might have to wait a few years to have a second go at the same cap again. 
Marc.
Very neat! I must get some of that aluminium tape.
I've had a go at the one in the Ekco TU 211, for the internal connections I used some of the innards of a length of 2.5mm twin and earth cable, which has doubled up as the support for the new capacitors.
The one thing that bothers me about sealing up the new caps inside the old can is what happens if the new caps vent? All the released contents get stuck inside the old can, and possibly blow it apart. I've thought maybe it'd be an idea to allow for this by drilling a small hole in the can, or if you are re-using the old base with it's terminals, drilling out the original vent hole. I'm probably just being paranoid though!
Regards,
Lloyd.
Lloyd said
The one thing that bothers me about sealing up the new caps inside the old can is what happens if the new caps vent? All the released contents get stuck inside the old can, and possibly blow it apart.
Regards,
Lloyd.
Hi Lloyd,
There should be no problem at all regarding venting, the original vent pip is still open to air in the cap housing base and will do the job if it were to become necessary.
Marc.
Vent in centre of tag base is open to air.
I understood the vent is to prevent explosion from excessive pressure should the capacitor fail short, the heat causes gassing which needs venting. Invariably they mounted upside down though which means they expel the nasty acidic ooze.
Maybe this is an incorrect assumption and it would be good to know definitively.
In the case of the re stuff the negative side is that should the capacitor start to vent, its unlikely to be a visible diagnostic being entombed in the old capacitor shell.
freya said
In the case of the re stuff the negative side is that should the capacitor start to vent, its unlikely to be a visible diagnostic being entombed in the old capacitor shell.
Hi Stephen,
Very good point, it would have to be purely down to electronic testing rather than physical sight for future failures.
Marc.
marc said
Whilst restoring one of my television sets I found that the main smoothing can had failed so thought I would show you how I re-stuff these multi capacitor cans.
Excellent tutorial! Also timely, I have a couple to do, my first, and I'll use your technique. BTW, if the original capacitor has a plastic sleeve, which I'd like to keep in place after the re-stuff, any suggestions?
FordAnglia said
if the original capacitor has a plastic sleeve, which I'd like to keep in place after the re-stuff, any suggestions?
In the past I've been lucky as I've only had a couple of these with the clear insulating sleeve to do. The plastic sleeves have slid off by holding the can and allowing heat from my hand to make the plastic more supple and rocking my hand back and forth until the sleeve let go. One particular cap sleeve was well and truly stuck so I soaked it in hot water again the make the plastic more supple and then whilst holding it under a running warm tap I used a pin to gently pull the plastic away from the metal at one end working round the can but only a tiny bit at a time until the water got in between the can and the plastic which eventually broke it's seal and the plastic slid off, It wasn't easy.
Oh by the way I re-wet the sleeve to slide it back on the can. Once the sleeve was put back onto the re-stuffed can I wafted a heat gun round it to flatten any pulls where I'd stretch the plastic with the pin.
Hope this is of some help.
Marc.
marc said
The plastic sleeves have slid off by holding the can and allowing heat from my hand to make the plastic more supple and rocking my hand back and forth until the sleeve let go.
Oh by the way I re-wet the sleeve to slide it back on the can. Once the sleeve was put back onto the re-stuffed can I wafted a heat gun round it to flatten any pulls where I'd stretch the plastic with the pin.
Thanks for the suggestions! I have one with a nice blue sleeve that I'd like to keep. The other is probably bare metal. Anyway, when I get back to the work bench I'll have a go at it.
FordAnglia said
Thanks for the suggestions! I have one with a nice blue sleeve that I'd like to keep. The other is probably bare metal. Anyway, when I get back to the work bench I'll have a go at it.
Let me know how you get on with them. Good luck.
Marc.
Excellent work indeed and certainly more professional looking than my own efforts when replacing the defective 4.33uF dropper capacitor in the 960 portable set.
Note it's absolutely essential to replace this component prior to testing if another example of these sets turns up. Myself and Dazzlevision learned the hard way as described in my, "Fault of Horror" thread on the UKVRR forum.
http://vintage-radio.net/forum/showthread.php?t=103917&highlight=fault+of+horror
freya said
I understood the vent is to prevent explosion from excessive pressure should the capacitor fail short, the heat causes gassing which needs venting. Invariably they mounted upside down though which means they expel the nasty acidic ooze.Maybe this is an incorrect assumption and it would be good to know definitively.
In the case of the re stuff the negative side is that should the capacitor start to vent, its unlikely to be a visible diagnostic being entombed in the old capacitor shell.
The thought occurs to me that you could insert a blob of softened wax into the vent, then in the event of the hidden cap blowing its top, any gassing would push out the wax plug without going bang - a simple and visible little tell-tale that would at least indicate major failure.
That's certainly a very neat-looking job and skilfully done. Many congratulations. I always find it interesting to see other peoples' solutions.
I do have a couple of questions, if you'll forgive me.
1. The component is marked "can not isolated", so originally the can will have been connected to the common negative. Has this feature been retained, and if so, how has contact been made with the can?
2. I have tended to avoid the use of adhesive tapes, because of the problem of the adhesive "escaping" from under the tape over time. Is Scotch Aluminium Tape conductive?
My approach to this problem has been to carefully open the peening on the can and go in from the end. This also works well with pre-war tubular wet electrolytics as found in (amongst others) Philips chassis. I would be the first to agree that this calls for a fair amount of patience and dexterity. Another method I am aware of is to turn the peening off, but clearly this requires access to a suitable lathe, and leaves the issue of reclosing the can afterwards.
