Barry Gershenfeld wrote:
>
> >>         Does a bang and a lot of smoke count? I've never actually completely
> >>vaporized a part... (feeling disappointed and inadequate now) :( TTYL
> >
> >Yeah, I think that counts ;)
>
>  Turn on board.
>  Nothing unusual happens...for awhile...
>  BANG!
>  Huh?  Look at board, oh, there is a pair of leads
>  where there used to be a part.
>  Then,
>  the sound of something bouncing off the counter across the room.
>  Go retreive part.  It's the can from the electrolytic capacitor.
>
> In an unrelated explosion, you know how you can spot check
> a board, and how the electrolytics always have their negative
> lead soldered to the ground plane?   Except, not on
> the negative supply :)


Ha ha! Bingo! Only a day ago I blew the main filter
cap on a stepper driver board I was testing, slowly
increasing voltage to the driver and testing
performance, I got to 35v and BANG (+ PSU went direct
to the 6 amp current limit which is never a good sign)

Turns out the 470uF cap was a 16v one... Whoops.
Surprising how it worked fine at 32v, but those extra
3 volts weren't appreciated apparently. The rest of
the board was undamaged. Cap bulged badly and went
short, it was red hot but I hit it with the freezer
spray and prevented it spraying acid steam all over
the workshop. At least the other 7 boards I built
had the 50v caps. :o)

Now I know the safe voltage overhead for that brand
470uF 16v at least. ;o)
-Roman

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