[RndTbl] Bad caps

Robert Dyck rbdyck2 at shaw.ca
Mon Mar 15 11:25:38 CDT 2010

Trevor Cordes wrote:
> I'm curious, was the bad caps issue widespread when you were in that job?
Any trends you noticed in brand, year, etc?  I certainly am
> noticing trends (like the badcaps issue did not stop in 2003) and would
love to hear someone else's experiences in the field.

I didn't notice a trend in brand, they all appeared to have issues. I did
notice that leaking caps caused the motherboard to completely fail; bulging
caps caused strange behaviour rather than complete failure, but it was in
the processing of dying quickly. Motherboards older than 2003 did have more
problems than newer ones, but the new ones also had bad caps.

There was a strong trend with LCD monitors. We got a number of monitors in
for repair, but were not able to repair most of them. The usual problem was
blown caps on the power supply. This occurred with Dell, Gateway, and NEC
monitors. Most of the monitors brought in were Dell. An occasional monitor
had a cracked display; you can't fault the manufacturer if someone sits on a
monitor. We couldn't swap parts because they all had the same problem: blown
caps in the power supply. I noticed all monitors with this problem had an
LCD display manufactured by HannStar. The monitors have 3 parts: LCD
display, power supply, and signal processing board. The two boards are not
made by HannStar, so you can't fault HannStar, but the power supplies are

I had a bit of a problem there. The owner wanted a technician who was able
to repair LCD monitors, but the service department foreman did not want
anyone to do so. So I was stuck between the owner and department foreman. I
did replace power supply capacitors for one monitor, but as soon as power
was applied the replacement caps blew as well. I had checked voltages, and
they were correct briefly but kept dropping out. Voltage would be Ok for a
fraction of a second, then drop, then come back. I thought replacing the
caps would fix it, but whatever blew the caps in the first place burnt out
the used replacements as well. Possibly a bad voltage regulator.

One customer had blown capacitors for his onboard motherboard audio. He
wanted to connect sound from his computer to his stereo. Unfortunately he
connected line out from his computer to line out for his stereo. He said as
soon as he connected it, he heard a pop. Sound on his computer hadn't worked
since. I opened the case while he was still at the counter; yup, 2 blown
caps. I told him we could replace the caps but the surge may have damaged
circuitry on his motherboard, and the service department foreman doesn't
like us to replace caps, so recommended a new motherboard. Besides, that
store charges $30/hour for normal desktop service work, but $60/hour for
soldering work. It would cost him less to replace the motherboard.
Unfortunately the foreman convinced him to buy a used computer. If he just
replaced his motherboard he would have had a brand new motherboard and all
the stuff he had before. The used computer cost more than a new motherboard,
and was older than his computer. The customer's father said he knows how to
solder so may replace the caps himself. I cautioned him that he has to
replace the caps with an exact match for capacitance and voltage, as well as
dielectric vs. ceramic, and has to be careful when soldering a multi-layer
board. Don't overheat the board, you can burn it easily.

The guys talked about bad power supplies in Antec cases, but I thought Antec
were premium cases. The computer I have at home has an Antec case, and I've
never had problems with it. The Antec cases we got through recycling while I
was there worked fine, their power supplies could be used as replacements
for customer power supplies. Some technicians also talked about AMD
processors not lasting, but again I didn't see that. Again, my computer at
home uses an AMD K7 Athalon Thunderbird processor. I've never had problems;
but then I was cautioned when I got it that AMD processors require good
cooling. I got a very good CPU heat sink. The only problem I've had with my
home computer was the video card. I got an G-Force3 v8200 when it was brand
new, top-of-the-line. The board died, but the retail store I worked for had
an exact match as a used card. I bought the used one at employee discount.
When I got home I found the used card had a seized GPU fan, but my old card
had a working fan. So I "Frankensteined" it together: took the working fan
from the dead card. I now have a program to monitor sensors, the GPU is
running hottest of all. I guess that's why that's the component that failed.
As for computers through the store: most computers had Intel CPU chips, but
that was due to volume of sales. I didn't see any trend with repairs: Intel
vs AMD.

That store sells 2 brand of hard drives: Western Digital and Seagate. The
Western Digital drives last perfectly for 3 years, but can fail after that.
Seagate drives are 50% more expensive, but more reliable.

Maxtor had manufactured hard drives, but were bought out by Seagate. In
their last days they replaced the metal top of their hard drives with a
heavy foil. The foil top drives failed a lot. IBM Deskstar hard drives also
had a reputation for failing, and I did see a number of them come in. Some
technicians called them "IBM Deathstar".

Rob Dyck

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