Capacitor question

[Kris]

Ive built a handful of the layouts here and I always solder the electrolytic caps with the long leg(positive) in the position of the grey mark on the layout. Is this correct? I've never had a problem before, but today I powered up a board to test it and a 100u electrolytic blew up.

Thanks,
-Kris

[boratto]

grey strip = negative
probably you invert things... it can blow up too if you are using low V, and unregulated power supplies.

[Kris]

boratto wrote

grey strip = negative
probably you invert things... it can blow up too if you are using low V, and unregulated power supplies.

Wow. Thanks for clearing that up, Boratto. I'm kinda shocked nothing's happened before and all my builds have worked. I guess it just shows I still don't know what I'm doing. hahah...thanks again!

[induction]

If it doesn't blow up, it will eventually fail closed-circuit (and probably sooner rather than later). If it's being used as a power filter cap, it will be a cause circuit from V+ to ground, which can burn components on the board or kill your adapter. If it's being used as a coupling DC blocking cap, it will eventually put DC where you don't want it, causing pops or misbiased gain stages. (In other words, your pedal will start to sound like crap.)

I recommend you go through your builds and replace all the reverse-biased caps. Don't just flip them around, they're already compromised. Throw them away and put in fresh ones in the correct orientation.

[Kris]

Great advice! I just went through my builds and checked to see what caps I have on-hand. I'm gonna switch them all out right away. Thanks so much for all the help!