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how do i know if my PSU bad?
Posted: Wed Nov 14, 2007 5:20 pm
by skier
how can i use this multimeter to check the PSU?(what wires to check and what their voltages should be)
Re: how do i know if my PSU bad?
Posted: Wed Nov 14, 2007 8:26 pm
by werty316
Connect the black lead to one of the black slots in the end of a molex connector and the red lead in either the red or yellow slot on a molex connector of your PSU to test the 5V or 12V rails.
To test the 3.3V rails put the red lead into the one of the orange slots on the 24-pin power connector.
Re: how do i know if my PSU bad?
Posted: Wed Nov 14, 2007 8:49 pm
by skier
cool! 11.90 V on the 12V rail, and 4.90 on the 5V
i was expecting it to be way off
-do i check the 3.3 by unplugging the main connector and testing it without turning it on, or do i have to jump the PSU?
Re: how do i know if my PSU bad?
Posted: Thu Nov 15, 2007 6:51 am
by bubba
just stick it down in from the top of the plug.
like this,
- psu test.jpg (43.9 KiB) Viewed 3992 times
Re: how do i know if my PSU bad?
Posted: Sat Nov 17, 2007 10:29 pm
by skier
ok, it said 3.23 on the 3.3V rail
so is a PSU fine as long as it is +/- .1V, or should it be even closer than that?
Re: how do i know if my PSU bad?
Posted: Sun Nov 18, 2007 8:30 am
by bubba
When you checked the voltages was the PC idle or at full load? If they were at idle, check them again with the PC under load. Put under a load and see where you are at.
Re: how do i know if my PSU bad?
Posted: Sun Nov 18, 2007 10:12 am
by DMB2000uk
It works in percentage tolerances.
The bare minimum is 5% and most good manufacturers go to 3%. And the really good supplies are tighter than 3%.
so for 5% they have to be between:
12v: 11.4v <--> 12.6v
5v: 4.75v <--> 5.25v
3.3v: 3.135v <--> 3.465v
And for 3% they can be between:
12v: 11.64v <--> 12.36v
5v: 4.85v <--> 5.15v
3.3v: 3.201v <--> 3.399v
Dan