14 Apr
2010
14 Apr
'10
12:07 p.m.
As you surmised, the problem was on the 12V rail,
which measured 0.5 ohms
That is 'guessed' :-). Please remember I've never seen this type of
drive, I've certainly not seen the faulty one, and I was working from a
possibly incorrect scheamtic. No, even 'guessed' is too strong a word..
to ground. It runs to quite a number of chips, but
was surprising easy to
follow around and through the various via holes. I dragged out the dremel
tool and did a binary search by slicing traces. Took the full logN tries,
but on the last cut I nailed a 4.7ufd / 16V tantalum cap with a dead short
:-).
I see. I hope that's the only fault. A capaacitor is easy to replace.
I could _really_ learn to start hating the blasted things. It seems like
almost every failure of this type has a tantalum cap behind it - on both
I know the feeling. Often power supply decouplers at least annouce their
failure with smoke signals. But yours didn't even do that.
audio and computer gear. Just finished resurrecting a
KLH/Burwen phono
noise suppressor in which EVERY blasted one of the things was shorted.
My eyes are crossed from staring through the board at a bright light...
Will patch traces and reassemble tomorrow. I'll let you know if things
cooperate.
I hope it works....
-tony