CJT <abujlehc (AT) prodigy (DOT) net> wrote


How many watts is your soldering iron rated for? I had bad luck with
the usual 25-35 watt irons and found that 40W was the minimum needed
for good results, with 45-50W being a lot better. Also some
desoldering wicks soak up much more solder than others, like the
ultra-fine or braided stuff, and I've been told that "No Clean" brand
is a favorite among technicians. It really helps to cut off the used
wick before proceeding tot he next pin. And if the solder doesn't
melt, sometimes it's best to just add more solder because apparently
the factory stuff has a higher melting temperature. Regular
electronics solder is 60% tin, 40% lead, but I once tried some 63% tin
solder that melted even easier.

www.mouser.com is sometimes cheaper than Digi-key and has no minimum.
Another good source is www.bdent.com , but I don't know about their
minimums.

In article <410184AB.70805 (AT) prodigy (DOT) net>, CJT <abujlehc (AT) prodigy (DOT) net>
writes

Sorry, I should have mentioned: we've got a decent temperature-
controlled vacuum desoldering station at work I can use. I'd planned to
cut each cap away, remove the legs separately, then use the desoldering
station to clear the holes.

Though I agree that it may take longer than half an hour Thanks for
the warning.

"Mike Tomlinson" <mike (AT) NOSPAM (DOT) jasper.org.uk> wrote

A professional tip from BadCaps.Net advises against using the solder sucker
more than twice for each hole. In fact, a stainless steel dentist pick might
work just as well or even better than the sucker. Some time ago, I've
collected quite a number of links related to the "Bad Caps on Motherboards"
fiasco. I'm listing some of the more informative ones in my article below so
that others may also benefit from reading them (or be amused by them) as I
have.
Al-U

-----
Alpha Uma's Collection of Links Related to the "Bad Caps on Motherboards"
Fiasco and How to Replace Bad Electrolytic Capacitors on Motherboards
(C): July 24, 2004

Disclaimer: Use the following information completely at your own risk. No
effort is made to guarantee the accuracy or completeness of the information
contained in this article or the information contained in the articles
linked from this article. Repairing a motherboard yourself obviously voids
the manufacturer's warranty on the motherboard.

Warning: Do NOT try to repair a motherboard yourself unless (1) you are a
trained and qualified electronics professional, (2) you can live without the
manufacturer's warranty on the motherboard, (3) the motherboard is already
dead, (4) you are perfectly happy to use your dead motherboard as a
paper-weight should you fail to repair it yourself, and (5) you will not
suffer, financially, physically or otherwise, if your workmanship fail to
repair it or make it even worse than dead. In other words, repair a
motherboard at your own peril. You have been warned.

The following links are collected in no particular order of preferences.

Testing Capacitors:
The poor-man's way uses just the ohmmeter component of a digital
multimeter.
Use an ESR meter or an oscilloscope if you want more accurate results.

Rough: Ohmmeter
Better/Popular: ESR Meter
Best (Perhaps): Oscilloscope

Useful Links on Testing Caps:
http://www.repairfaq.org/sam/captest.htm
http://www.101science.com/101captesting.htm
http://octopus.freeyellow.com/esr.html
http://octopus.freeyellow.com/99.html
http://www.fullnet.com/u/tomg/esrscope.htm

Professional Tips and Services on Replacing Capacitors on Motherboards:
From Badcaps.Net:
http://www.badcaps.net/tips/rem/
From Gary Headlee's MotherboardRepair.Com:
http://www.motherboardrepair.com/index.php?sec=images

Replacing Capacitors on an ABIT VP6 Motherboard:
http://www.vp6-board.com/caps1.htm

How "Anyone" Can Replace Capacitors:
http://www.overclockers.com/tips1081/

How to Get It Done the "Ugly" way:
http://www.overclockers.com/tips758/

Some General Tips on Soldering Skills:
http://www.gameconsolerepair.com/solderinghelp.html

Historical Background on the "Bad Caps" Fiasco:
Leaking Capacitors Muck Up Motherboards (from IEEE Spectrum Online):
http://www.spectrum.ieee.org/WEBONLY...eb03/ncap.html
Low-ESR Aluminum Electrolytic Failures Linked to Taiwanese Raw Material
Problems
(from Passive Component Industry Magazine):
http://www.niccomp.com/taiwanlowesr.htm

Probably More Than You Want to Know About Electrolytic Capacitors:
Basics:
http://www.oz.net/~coilgun/theory/capacitors.htm
Technical:
http://www.nichicon-us.com/english/lib/alminium.pdf
http://www.faradnet.com/index/toc.htm
http://www.aavidthermalloy.com/techn...apacitor.shtml
http://www.elna-america.com/MTBF.htm

Copyright (July 24, 2004) Alpha Uma: Permission is hereby granted to copy
and reproduce the this article provided that (1) the exact content remains
unaltered, (2) the exact content is completely reproduced including this
copyright notice, and (3) credit is acknowledged with the phrase "Reprinted
with Permission from Alpha Uma".

On Sat, 24 Jul 2004 08:42:27 +0100, Mike Tomlinson <mike (AT) NOSPAM (DOT) jasper.org.uk>
wrote:

I have found this to be the best way.
The pads and traces are too delicate to do
any other way. Using a solder sucker and
heating em too long just raises the pad and
ruins it.
So I cut away the old cap, expose each leg,
and with a pair of small needle nose pliers,
I heat it, while gently pulling the leg....comes
out cleanly while applying the least amount
of heat.

"Mike Tomlinson" <mike (AT) NOSPAM (DOT) jasper.org.uk> wrote

Hey, Mike,

Have you fixed it yet?

Al-U

In article <nNFNc.129576$ek5.11297@pd7tw2no>, alpha_uma
<no_one (AT) nonesuch (DOT) com> writes

Hi Al,

I have the replacement caps but haven't had a chance to fit them yet;
have been away on a Cisco course. Will post back early next week.

Mike

In article <nNFNc.129576$ek5.11297@pd7tw2no>, alpha_uma
<no_one (AT) nonesuch (DOT) com> writes

Done today.

Replaced all nineteen caps listed in a previous post. I found a 22w
soldering iron was insufficient to melt the solder where the hole
connected to a +ve or ground plane and had to use a 45w iron, working
quickly to prevent damage.

I replaced two caps at a time, cutting each cap in half using a pair of
snips. The remaining bit of cap is then easy to pull away from the
board with a pair of pliers, leaving two pins soldered in the holes. I
applied the iron to each pin, lifting it out with a pair of needlenose
pliers, then added more solder to each pad before clearing the hole with
a hand held solder sucker.

A quick check with a magnifying glass (some PCB tracks run very close to
the cap mounting points and there is a possibility of shorting) and
remounted the board. After a couple of test passes using Memtest86, it
fired straight up into Redhat 9 and is running fine.

The machine also does not seem to be running as hot; the air exhaust
from the PSU is markedly cooler, and lm-sensors says the CPU temp is
48C; it used to be about 53-54C. This is a Duron 1300 overclocked to
1400. I'm using the HoneyX BIOS.

Replacing all the caps took about an hour. But I don't think I would
bother doing it again on a cheap board.

Mike

On Sat, 31 Jul 2004 22:13:26 +0100, Mike Tomlinson <mike (AT) NOSPAM (DOT) jasper.org.uk>
wrote:


Where did you get the replacement caps from?

In article <1apog0p2vo639hll6m8f2qvb91d26lbtag (AT) 4ax (DOT) com>, TX_Dude
<ric.duncan (AT) verizon (DOT) net> writes

I'm in the UK, so got them from Farnell. Here's the info from an
earlier post:

"I wasn't able to find 1800uF 6.3v, so have ordered 2200uF 6.3v to
"replace those.

"These are high-quality, low-impedance, 105C Rubycon caps. For anyone
"who's interested, the Farnell (www.farnell.com/uk/) part numbers are:

"767360 x8 1500uF 6.3v
"769071 x1 1500uF 10v
"768005 x10 2200uF 6.3v

Total cost was ukp9 (about us$16) including delivery.

--
..sigmonster on vacation

In the US, I got replacement caps at www.electronix.com.

dan


TX_Dude wrote: