faulty capasitors

  • Thread starter Thread starter Juve
  • Start date Start date
J

Juve

HI,

Mobo has been on and off for the last couple of weeks. (occationally
harddrive is not detected at start up) Someone suggested this might be
due to bad capasitators. How does one gauge the "capasity" of
capasitors? Multimeter?
OR
 
Juve said:
HI,

Mobo has been on and off for the last couple of weeks. (occationally
harddrive is not detected at start up) Someone suggested this might be
due to bad capasitators. How does one gauge the "capasity" of
capasitors? Multimeter?
OR
Click to expand...

No need for a meter to check the capacitors on a motherboard. When they go
bad the ends of them rupture and leak. Visually check each of them and if
they are leaking a substance (usually dark in color) then they are bad, if
not don't worry about them.

For what it's worth, the capacitors usually have a couple of little grooves
in the ends of them. They are actually there to allow the capacitor to
break open at that point and allow pressure to escape in an emergency.
During an electrical short the older one's that did not have the relief
grooves would explode like a firecracker causing much damage.
 
Juve said:
HI,

Mobo has been on and off for the last couple of weeks. (occationally
harddrive is not detected at start up) Someone suggested this might be
due to bad capasitators. How does one gauge the "capasity" of
capasitors? Multimeter?
OR
Click to expand...

Bulging caps indicates internal failure and a pressure buildup.
The stress relief lines break open, when enough pressure is
present. The bottom (rubber) seal, can also start to
protrude below the capacitor body, and cause the cap to
tilt on an angle.

http://www.badcaps.net/images/caps/kt7/image004.png

Brown color on the top of the caps, is from leaking electrolyte.
The brown liquid can also dry on the motherboard surface. (This
is a picture of the inside of an ATX supply, but the same problem
can happen on the motherboard.)

http://upload.wikimedia.org/wikipedia/commons/8/84/PSU_Caps.jpg

Capacitance can be measured with some multimeters, if they have
a capacitance option. My $100 meter can measure capacitance, but
only for a restricted set of ranges. If the capacitor is
resistively leaky, I'm not sure whether the multimeter could
get a proper reading or not.

Paul
 
Juve said:
Mobo has been on and off for the last couple of weeks. (occationally
harddrive is not detected at start up) Someone suggested this might be
due to bad capasitators. How does one gauge the "capasity" of
capasitors? Multimeter?
Click to expand...

www.badcaps.net

As others have said, you'll usually see a bulged top on a bad
capacitor, but a multimeter or even a capacitance meter will rarely
show anything wrong with such capacitors. An ESR (equivalent series
resistance) meter is needed, but it's not useful for motherboards
because the capacitors are wired in parallel.
 
Juve said:
HI,

Mobo has been on and off for the last couple of weeks. (occationally
harddrive is not detected at start up) Someone suggested this might be
due to bad capasitators. How does one gauge the "capasity" of
capasitors? Multimeter?
OR
Click to expand...
Because you say "occationally harddrive is not detected at start up" I
like to ask, did you check the CMOS battery?
If that's the culprit the computer time, while the computer has been
off, might be wrong.
 
Juve said:
HI,

Mobo has been on and off for the last couple of weeks. (occationally
harddrive is not detected at start up) Someone suggested this might be
due to bad capasitators. How does one gauge the "capasity" of
capasitors? Multimeter?
OR
Click to expand...


Might also be your PSU, try changing it:)
 
Open up the case and look with a flashlight. Bad capacitors will be
discolored on top. Usually due to air moisture.
 
Somewhere on teh intarwebs "Maggy" typed:
Open up the case and look with a flashlight. Bad capacitors will be
discolored on top. Usually due to air moisture.
Click to expand...

Once upon a time all advice given here was qualtiy advice....
--
Shaun.

DISCLAIMER: If you find a posting or message from me
offensive, inappropriate, or disruptive, please ignore it.
If you don't know how to ignore a posting, complain to
me and I will be only too happy to demonstrate... ;-)
 
Don't be so quick to criticize Shaun. Poor quality mobo's (cheap) often
react badly to humidity.
I've seen the results and believe me, (or not) the top end of capacitors are
very prone to corrosion.
this is just one possibility to the op problem.
 
Somewhere on teh intarwebs "Maggy" typed:
Don't be so quick to criticize Shaun. Poor quality mobo's (cheap)
often react badly to humidity.
I've seen the results and believe me, (or not) the top end of
capacitors are very prone to corrosion.
this is just one possibility to the op problem.
Click to expand...

Learn to post correctly. Top-posting is for 'tards.


You now say "this is just one possibility to the op problem". You previously
said "Bad capacitors will be discolored on top".

Going by your first statement, that bad capacitors will be discloured on
top, the capacitor in this picture can't possibly be bad as it's top isn't
discoloured:

<http://test.internet-webmaster.de/upload/1225234719.jpg>

However, when the capacitor is viewed from the side it becomes obvious that
something is amiss:

<http://test.internet-webmaster.de/upload/1225234757.jpg>

So, as it's not discoloured on the top is this capacitor fine?

That would indeed be odd as, when I replaced it, the graphics card worked
fine again. It didn't with that capacitor fitted.
--
Shaun.

DISCLAIMER: If you find a posting or message from me
offensive, inappropriate, or disruptive, please ignore it.
If you don't know how to ignore a posting, complain to
me and I will be only too happy to demonstrate... ;-)
 
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