The problem Matt ran into was misreading a value on a cap .It can be made
whether you do all the caps at once or one at a time. Matt took all the
necessary precautions needed to avert any wrong installations of the caps by
noting each caps place, value and polarity rather than rely on the circuit
markings (to me, that shows some experience there) Though it is more time
consuming and there is more chance of a mistake, I see no problem with
removing all the caps at once so long as those steps are taken.

"William" wrote in message
...

"Matt J. McCullar" wrote in message
et...
Something I learned the hard way...

I was replacing a bunch of electrolytic capacitors in a video monitor. I
removed the originals all at once, taking careful notes about each
location,
its reference designation, and the value and voltage of each capacitor.
All
the original caps went into a zip-lock bag.

Then I got a fresh batch of new capacitors, tested each one first, and
installed them in one go. I carefully checked off each capacitor on my
list
as I went. (Another tip: I colorize the top of each new electrolytic
capacitor with a red magic marker so I can readily see if I've missed
something later.)

This was about 30 capacitors. It's very easy to put one in backwards, as
you well know. I was very, very careful.

I apply power, and...

BOOM! One cap literally got blown completely out of the monitor! It
sailed
past my ear and landed about three feet away! It was a small one, a 10
uF,
50 volt job, but it learned how to fly that day.

Well, poop. I quickly removed power and found the location of the fried
capacitor. I checked my notes again. Something in my gut told me to
re-double-check. I went back through the bag of original capacitors and
checked off each cap's value and voltage rating.

Now, here's the golden moment: I found my mistake. I had the right
value
of capacitance, and I'd installed it correctly. My mistake was the
voltage
rating. I had installed a 50-volt capacitor, which is what the original
capacitor was rated for. But... The original capacitor had some white
rubbery gunk on it; that had been applied on the circuit board at the
factory to keep parts and wiring from moving around much. It's basically
a
rubberized version of hot glue. This white gunk had hardened all over
one
side of this cap, and it had masked something critical: one digit.
That's
all, just one digit. I removed the gunk.

The original capacitor was rated for 250 volts, not 50! No wonder the
replacement cap exploded.

So, keep this in mind the next time you're replacing a bunch of
capacitors
or other electronic parts: make sure you can read ALL the numbers and
letters on them!!!

Matt J. McCullar




I never remove ALL the caps at one time. I do it one at a time and verify
voltage and polarity of the old cap first before installing the new
one....sometimes the markings on the circuit board are wrong.