JJ Punctured Cap Can (With dissection photos)

[Meat&Beer]

One of the JJ cap cans for a build I'm working on got a tiny little hole in it from an allen wrench multi tool, the hex nut that holds it together. Must be I was tightening the mounting nut underneath and the tool pivoted, and was in just the right position to poke a can with the sharp corner of the nut.

I built just enough of the amp to make sure the PSU was working properly and to locate iron. This was noticed when I was taking it apart, so it did have full unloaded B+ on it.

What do you guys think? There is/was no leaking of internal goo. I'm not sure if it's actually punctured, or if it's a clean tiny dent. Also don't know what the internal make up is to be able to give an assumption of reliability at this point.

These caps aren't cheap, I'm kinda ticked off to say the least. If I need to buy a new one, I certainly will. But thought I'd ask here for opinions first...

*edited title for further reference*

[Meat&Beer]

Thanks GKT, I really appreciate it! I'll put a 'lil dab of silicone in there. It's a single, not a multi cap.

Anyone else care to weigh in if this makes them squeamish?

[matt h]

DUDE! You should have told me it was a single! I assumed a multi...

I'd say GKT is on the money. There's a huge, huge likelihood that between the outside of the "can" and the inside of the actual "cap" there's a gap to end all gaps. I'd throw something on the whole to prevent anything from catching it/widening, corrosion, gunk, etc getting where it should be. Think russian stacking dolls with like, the middle three dollars removed and only the tiny one inside the big one with its feet glued down to the bottom.

[VacuumVoodoo]

That goo is the electrolyte in gel form. It's what makes it work. At working temperature it liquifies. It will leak out. The electrolyte will spread all over amp's innards. The cap is junk. It's terminally ill.
Read detailed data sheets, the part dealing with handling and application notes. It says even if the cap only dropped on a hard surface it's lifetime will be reduced and you shouldn't use it in any case. No, not JJ datasheet, it's too brief.

[Stevem]

Be on the safe side and for the 13 dollar cost change it!

[Meat&Beer]

Well, it was only realistically going to take one person to tell me to scrap it for me to make up my mind. Seems the price went down a little since I got them at least....

I'll make a video cutting it open and spilling its guts if anyone's interested? I'm going to cut it open now anyway, my morbid curiosity won't allow otherwise. Might as well capture the experience!

Thanks for the input guys!

[Structo]

Yep, RR that cap.

I always like to post this picture when there is a question about replacing Filter Caps.

[img:640:480]http://i23.photobucket.com/albums/b392/ ... C01888.jpg[/img]

[Meat&Beer]

Picture results of dissection, for science!

Better to side with caution, but in this case, I doubt it needed to be done. However, I couldn't have came to that conclusion without having actually done it.. The dent was in fact a tiny dent, not a puncture. There is a very small air gap between the capacitor and its shell. Otherwise, that's all cap! That air gap is in all reality, very negligible. Maybe 1/32" all the way around? I suspect the cap was filled with the hot wax like yellowish substance you see, and shrank a small bit with cooling.

Results may vary with manufacturer, this isn't meant to be an all encompassing result/determination for the cap can kingdom. Precautions were taken and protection was worn, just in case it decided to squirt or bleed or anything like that.

JJ 500uf 500v cap can... Destroyed.

[Meat&Beer]

Oh, and by the way! The $13 price quoted by stevem above, is actually a Black Friday/Cyber Monday deal at thetubestore.com, so if you're in need of caps like this or anything else from them, now is the time to order! These are normally more in the $20 range. So, the price didn't go down from what I remembered them to be, they're just on sale at the moment.

[gktamps]

M&B,
Thanks for posting those pics. The can cap I disassembled was a Mallory multi-value, and the capacitor didn't fill the entire space within the can; the black goo I referred to earlier filled the remaining space. After VV posted his warning that the electrolyte would leak I thought it better to delete my suggestion to silicone the presumed hole.
It was interesting to see the JJ construction, and if this happens to me I will first slit the shrink wrap to inspect the can before tossing it, and it the dent is as small as the one you have, I would personally use it.
Glad you were able to get a replacement for a reasonable price.
Greg

[Leo_Gnardo]

Thanks m&b for putting up a couple photos, all that's needed to show what's inside. No movies necessary. Whew, good thing they put 'em in nice cans, they sure ugly inside!

[Davidg]

The construction of those look more like vintage-old school cap construction than any of the others I have seen the inside of. I got a few of those laying around I haven't used yet,Hmmm. Now if I can just get some time to fire up the old Hakko.. Good to see there's not any baby caps hiding inside the can, I know everyone has opinions but I am very pleased with JJ and think think they make some of the best tubes overall for new production stuff. Looks like their caps are good quality too. Good to see a maker of stuff we need growing and adding products and doing it right instead of getting greedy trying to maximise profits then dying out . Maybe Sprague and some of the others could learn a thing or two from them.

[rp]

The construction of those look more like vintage-old school cap construction than any of the others I have seen the inside of.

I was thinking the same thing. It's good to see. Wonder what's in the F&Ts?

Also can't help thinking the world is still using this paste & foil technology pretty much unchanged for 100 years, e-caps are like the sharks of electronics evolution. Viva e-caps.

Whoever owns that Marshall in Toms pict needs to replace that cap. I believe these are vintage correct:

[Structo]

Hehehehe


Yeah it's a mess!

Party Popper indeed!

Awhile back when we discussed the counterfeit E caps, there were many examples of large cans filled with smaller radial caps.

Then of course the was the year or more where there were defective E caps on the market, where a corporate espionage person stole an electrolyte paste recipe.

He didn't get it right and there were thousands of these faulty caps on the market.

Computer motherboards were affected by this as many power supply caps leaked or exploded.

There were even cottage industries that emerged for repairs of the computer boards.

I think the one that upset me most was the higher priced caps that had small caps in them.
Sometimes not even close to the rated values.

Electrolyte story:

http://spectrum.ieee.org/computing/hard ... therboards