URGENT! Capacitor about to explode! What should i do ?

[bleubleu]

Hi!

I just built a small 18V power supply (LM317 based). I use power from a 18VAC wall power supply, convert it to DC, regulate it. You get the picture.

I plugged it for the 1st time for a quick test.
I started to smell something strange after 5-6 seconds, I unplugged everything.
Now one of the capacitor is all inflated and huge. I let everything cool for 2h but I am still shit scared of touching the whole thing.

What should i do now Can I cut it off safely, should I try to discharge it ?

I looked at those videos of exploding caps on youtube and it is scary stuff.

Mat

[brett]

Chances are that you have the polarity wrong, or are using the cap across AC volts.

[bleubleu]

My question was more about how NOT TO DIE replacing that cap!

Mat

[zachomega]

Probably won't be any danger as long as you unplug the thing from the wall. 

18 volts really isn't that much. 

If you are that paranoid, short the leads of the cap with a screwdriver (with a plastic handle). 

-Zach

My question was more about how NOT TO DIE replacing that cap!

Mat

[Paul Perry (Frostwave)]

It isn't going to burst now it is cooled down.
just unsolder it.

Either you have a wiring mistake or you put it in backwards. Or both.

[drewl]

BLOW IT UP! BLOW IT UP! BLOW IT UP! BLOW IT UP!
It's soooo cool to watch!

[puretube]

put on your SAFETY-glasses FIRST!

[niggez]

Do they actually blow up or doe they ooze do death?

[R.G.]

Safety glasses. There is hardly ever a time when safety glasses are not appropriate. The laser lab out at the research center had a sign saying "Use safety goggles to protect remaining eye."

Modern electro caps are designed with weak places in the outer metal shell so those places tear and it vents first. It may vent and plop out a bit of goop, but it probably won't even vent now that's it's cool.

Blown up electro caps smell terrible. Or at least they did way back when. I got the diodes backwards on a power supply board one time and my lab tech was testing it for me. Vented a 3" diameter by 8" long filter cap (big power supply...) through the rubber plug which vents large computer-grade caps. Sprayed ethyl-methy-hydroxy-nastysmelline all over the wall and ceiling. Horrible smell. Plastic cased diodes did explode, though, and sprayed bits of case all over the lab. Pete (the lab tech) never would fire up power supplies the first time for me after that.

[ayayay!]

Blown up electro caps smell terrible. Or at least they did way back when. I got the diodes backwards on a power supply board one time and my lab tech was testing it for me. Vented a 3" diameter by 8" long filter cap (big power supply...) through the rubber plug which vents large computer-grade caps. Sprayed ethyl-methy-hydroxy-nastysmelline all over the wall and ceiling. Horrible smell. Plastic cased diodes did explode, though, and sprayed bits of case all over the lab. Pete (the lab tech) never would fire up power supplies the first time for me after that.

Noobs note:  Even R. G. started somewhere, but his stories are more hilarious.   

[johngreene]

Modern electro caps are designed with weak places in the outer metal shell so those places tear and it vents first. It may vent and plop out a bit of goop, but it probably won't even vent now that's it's cool.

That sure took all the fun out of it when they started doing that. At one point in my past, while practically the entire company was at a trade show or on vacation, I decided to do everyone a favor and 'dispose of' all the old electrolytics in the engineering stock room without the scores in the top. One at a time. By connecting them backwards to a BAPS and ducking behind the lab benches.

--john