I knock off a capacitor from a computer motherboard. And i lose the
capacitor. I am sure that it is a capacitor since it is marked as C256
The capacitor is very small, it is smaller than an ant.It has no
marking and only a single color stripe at the middle.
I know the color of the capacior since i have an identical board.
Question:
Since there is no marking on the capacitor, is there any way to find
out the rating of it?
Also i have couple of junk boards, can i just remove the one with the
same color and size,and replace it?

Hmm , a single colour stripe in the centre , doesn't sound like a
colour coding system. Desolder one from a working board and measure it
with a capacitance meter. Voltage rating should be around 25 V unless
it's part of a dc to dc convertor section .

On 29 Jul 2005 23:26:48 -0700, wrote:

I knock off a capacitor from a computer motherboard. And i lose the
capacitor. I am sure that it is a capacitor since it is marked as C256
The capacitor is very small, it is smaller than an ant.It has no
marking and only a single color stripe at the middle.
I know the color of the capacior since i have an identical board.
Question:
Since there is no marking on the capacitor, is there any way to find
out the rating of it?
Also i have couple of junk boards, can i just remove the one with the
same color and size,and replace it?


I work on MB's everyday, and have to replace various components such
as you describe (ant like). They do have standard sizes, and power
carrying capabilities. Your cap may be either an "0402" or "0603"
size. The values are NOT marked any way on the caps (they are on
resistors, if you have a strong enough eye loop to read them). Since
values range from 3pf to 0.1uf for these chip caps on most MBs, it is
probably not a good idea just to grab one that "looks" the same, as a
3pf 0603 cap looks the same as a 0.1uf 0603 cap.

If you are very fortunate, it was only a "noise cap", and the MB will
probably work fine without it. However, it could just as easily be a
critical cap, without which the MB will be rendered into a fancy
door-stop.

You might be able to find out the value by emailing tech support of
the MB manufacturer. Once you know the value, you can buy a
replacement from a place like Digi-Key (www.digi-key.com) .

Good luck!

Actually, it is not a stripe. See the picture

http://qcpages.qc.cuny.edu/~slee18/Capacitor.jpg

wrote in message
oups.com...
Actually, it is not a stripe. See the picture

http://qcpages.qc.cuny.edu/~slee18/Capacitor.jpg


In my experience, caps of that type are either .1uF or .01uF.

Probably work fine without it.

Mark Z.