Electrolytic cap starting to bulge

[BoxOfSnoo]

I started to search for this, but couldn't come up with the right terms,  I guess.  I built an Echo Base, and noticed one electrolytic cap, the 100uF just before the LFO was starting to bulge out slightly.  I figured I caused some issues when debugging, so I replaced it with another one... and now after a few days I notice the new one doing the same thing...

What causes this to happen?  It's rated at 15v, and I'm only running the project at 9v.  The orientation is correct, I've double (triple)-checked.  If it wasn't, it would be more drastic of a failure than that, right?

[Paul Marossy]

Huh, weird. It shouldn't be doing that if you are giving it less voltage than it's rated for. Maybe it's a bad batch of caps or something?

[TELEFUNKON]

have you measured the voltage of your power supply? 9V?

[BoxOfSnoo]

have you measured the voltage of your power supply? 9V?

9.1v according to my meter.  It's a Godlyke Power-all.

[Paul Marossy]

Sounds like a bad batch of caps to me. Or they are like 5V caps that have the wrong markings on them.

[JKowalski]

Are the caps getting hot when they are running? Are they old stock caps?

Careful when you have it turned on though, don't put your face near the top of the cap - a common failure of electrolytic is where they develop a short, draw excess current, and as a result the electrolytic paste inside boils and the cap explodes out the top (or all round if it is bad enough!).

[Brymus]

Yeah I blew up a 450V cap once by using the wrong type of rectifier,way too much voltage the cap blew sending a huge cloud of smoke up into my garage,and that oil inside them doesnt smell to good when it gets boiled into smoke...

[MikeH]

I'd also measure the voltage on either side and make sure it's oriented appropriately- you might have it in correctly according to the layout, but the layout might be wrong

[phector2004]

Are the caps getting hot when they are running? Are they old stock caps?

Careful when you have it turned on though, don't put your face near the top of the cap - a common failure of electrolytic is where they develop a short, draw excess current, and as a result the electrolytic paste inside boils and the cap explodes out the top (or all round if it is bad enough!).

http://en.wikipedia.org/wiki/Capacitor_plague

a possibility, maybe? where'd you get them from?

[Paul Marossy]

Yeah I blew up a 450V cap once by using the wrong type of rectifier,way too much voltage the cap blew sending a huge cloud of smoke up into my garage,and that oil inside them doesnt smell to good when it gets boiled into smoke...

Yeah, I bought a Marshall 9005 power amp from a friend a few years ago. It was sitting in his garage for a few years (uninsulated garages here in Las Vegas can be probably 135 deg F in the summer). I fired it up after I got it home and one of the filter caps blew up. That was one of the nastiest odors I have ever smelled. I hurried that thing out of the house ASAP! 

[col]

One of my sons received a nasty burn to his eyeball when a cap exploded in ashorting digital telly box! Beware.

BTW I had a near miss today while driving as i has some spare AA batteries in my pocket for my camera and I also had a large bunch of keys in there. Just caught it before I set on fire!!!!

Col

[StereoKills]

I replaced some bad electrolytic caps that had bulged open and were starting leak on a motherboard a few months ago. Replace them as soon as possible.

[BubbaFet]

All of the electrolytic caps in my Super Hard On are bulging too! 

[StereoKills]

That and on the Swollen Pickle are the only times I'd consider it normal 

[JKowalski]

That was one of the nastiest odors I have ever smelled. I hurried that thing out of the house ASAP! 

The only one I've blown so far has smelled exactly like shellfish. 

[Hides-His-Eyes]

BTW I had a near miss today while driving as i has some spare AA batteries in my pocket for my camera and I also had a large bunch of keys in there. Just caught it before I set on fire!!!!

Col

I had that once before a gig. I just randomly felt something very, VERY warm in my pocket and it was a 9V battery shorting out against my keys.

[knealebrown]

BTW I had a near miss today while driving as i has some spare AA batteries in my pocket for my camera and I also had a large bunch of keys in there. Just caught it before I set on fire!!!!

Col

I had that once before a gig. I just randomly felt something very, VERY warm in my pocket and it was a 9V battery shorting out against my keys.

you have just made me realise why i had a 9v bat getting realy warm in my pocket a few months back, although mine was likely to have been a coin. Simple explanations eh? i thought it was a ghost doing it........

[MikeH]

Yeah I did the same thing driving to a gig with a battery and a slide in my pocket.  Just about set my junk on fire; it's a miracle I didn't crash the car.

[phector2004]

I've never noticed anything strange when shorting AAs (no sparks, nothing), but you should definately be careful around 9vs... a lot of people keep 9v batteries and steel wool to start emergency fires 

[ayayay!]

I've never noticed anything strange when shorting AAs (no sparks, nothing), but you should definately be careful around 9vs... a lot of people keep 9v batteries and steel wool to start emergency fires 

Yeah my brother's girlfriend had a taser that worked off of a 9 volt. (That's all it takes)   She tried it on me one day.

My brother married someone else.

I love my brother and his someone else.