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Bad cap - Replace a 2200µF with a 1800µF

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October 14, 2012 9:56:04 PM

Hi.

I have an old P4 computer that have a couple of defect capacitors.
Motherboard is a WB72 and the blown cap is labeled E2 (printed on mobo).

I just got an old mobo that had 1800µF caps (voltage and temp range is the same) that I plan to use as replacement cap for the old 2200µF.

Can anybody tell me if you thing that the new cap might be too small?

I'll use that cap anyway if I don't get another replacement soon.


Thanks.
a b V Motherboard
October 15, 2012 12:38:37 AM

You can change the voltage value (up) but not the microfarad, stay with the 2200uF. I have repaired around ten motherboards and used the same valu caps. with no problems.
November 8, 2012 2:17:10 PM

has to be 2200mf and same voltage or higher voltage never lower.
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a c 156 V Motherboard
November 8, 2012 3:56:26 PM

SHOULD be 2200 mfd; 1800 MAY work. Assuming your soldering skills are up to it, you have nothing to lose by trying.
a b V Motherboard
November 8, 2012 5:01:03 PM

Increasing capacitor working voltage ratings is not a good idea since higher voltage caps have thicker dielectric which means higher losses and worse ESR/ESL.

The quality of replacement capacitors is often more important than the nominal capacitance. Most of the failed capacitors I have replaced had only 0.7-1.2A RMS current ripple rating. My replacements are rated for 2.6-3.6A.

Decreasing capacitance however is never a good idea for power decoupling since it practically always means more supply noise and could cause output to change too quickly for the feedback circuitry to respond properly. When I replace input/output caps in PSUs, I try to bump uF ratings up a notch or two if the footprint and clearances can accommodate them and I happen to have them in stock.
November 18, 2012 8:47:25 PM

Hi.

Yesturday I did the soldering job and replaced two bad caps with two caps from Samxon.

Sadly, when starting up I never got any signal to the screen.
I did try to:
* Replace vga card.
* Remove any unneccesary components from mobo. RAM included.
* Reset the bios.
No success :( 

However, I did use a screw clamp directly on the cpu cooler in order to keep the mainboared into place, so that may have being too much for the mobo even if I never applied severe force onto the mobo.

Also, the caps could be damaged from the heat (uset a hot air gun to remove them from spare parts mobo). Or that the mobo just didn't cope with the heat from the solder iron. All three reasons seems fairly possible.

I've done many repairs on tv's and audio equipment, but this is my first soldering on a computer mobo.
!