9 Sep
2006
9 Sep
'06
1:29 p.m.
So what I want to know is how the thing functioned at all without the =
cap (burnt carbon acted as a capacitor in some way)? and what caused it =
That cap[acitor was probably a tantalum electrolytic (this being the type
normally known for exploding in this manner) and was probably a supply
decoupuling capacitor. That is, it was connected across the supply lines
to come component (say between +5V and ground), close to that component
to probide a local store of energy. Otherwise, the sudden current surge
when the device switehd could cause excessive voltage drop across the
supply traces to that component, and thus cause further problems.
That said, ther'es often a fair ammout of over-enginnering when it comes
to such capacitors. As I put it 'Decoupling capacitors are cheap, my time
in finding obscure glitches isn't'. So it's common to put at least one
per chip, at least on experimental/low-volume-production boards.
And therefore if one failes, it's likely the board will keep running.
I've had tantalum capacitors faile while a machine is in use, and the
machine just carries on.
to stop working.
Now that I don't know, but it may have nothing to do with that capacitor.
-tony