On Thu, 31 Mar 2011 10:27:03 -0700 (PDT), "larry moe 'n curly"
wrote:

Jeff Liebermann wrote:

Out of about 7 machines, I
managed to reverse the caps on 4 of them. All had the silk screened
stripe marking the "+" end instead of the usual "-" end. I didn't see
the "+" silk screened marking or bother checking the square pad, until
Phil Allison pointed it out in the first photo.

BTW, not all Dell mobos are marked that way.

Yep. This is the first time I've seen boards marked that way and I've
been dealing with PC's since the Apple ][.

Do you mean you don't write a red dot next to the positive lead when
you remove each capacitor? I do that because I've come across
circuit boards that were marked wrong.

I usually take a photograph. For major repairs, such as laptops, I
also print the photo, and mark any parts I replace. However, I
haven't found it necessary to mark the capacitor polarity. I have run
into some that were marked backwards, but that was maybe 10 years ago.
More commonly, capacitors where the silk screened markings are UNDER
the capacitor, where they can't be seen. When I do mark something on
the board, I use a UV pen for the top, and whatever I have handy for
the bottom (which can't be seen).

Worst case are some video cards, where the annular ring around the
solder bad is so narrow, that any attempt to solder the pad will
result in a guaranteed solder bridge. These also tend to have no
visible polarity markings of any kind, which adds to the challenge.

The problem here was that these machines were mine, not my customers.
So, I simply ignored all of this, and blundered onward with no photos
or markings.
--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com
# http://www.LearnByDestroying.com AE6KS