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I just did a Paper Clip test on my PSU. I got nothing. That tells me that the PSU is dead, right?

But:

When I did a breadboarding test, the heatsink fan was activated, plus an LED light on the front panel was also on. Is this possible with a dead PSU?

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What makes you think the PSU is dead? What failed to make you start testing it? –  ChrisF Jul 16 '11 at 11:13
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2 Answers 2

Some PSUs will not start up properly unless they are connected to a load, so if you did the paperclip test with no devices connected to the PSU then it may 'play dead' - and that's also why things seemed OK when you tried again later with the PSU hooked up to some PC parts.

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There's an interesting discussion on this here playtool.com/pages/psuunderload/mincurrent.html - apparently not only is this a problem for unloaded power supplies, but also for some of the higher output ones being coupled to a system that's very power-efficient. Not enough current draw on the 12V rail, and it will either not power up, or only power up briefly. Paper clip test really needs to be depreciated, as max load goes up, so does minimum load, particularly if the manufacturer is trying to control costs. –  Stephanie Jul 16 '11 at 12:28
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Also... "A modern ATX supply has minimum loads of about 1A on the +12 supples, 0.3A on the +5V, and 0.5A on the +3.3V. The -12V and the +5V standby ouput have no minimum current. These figures can be used as a general guide if the exact specifications are unknown." from mysite.du.edu/~etuttle/electron/elect62.htm –  Stephanie Jul 16 '11 at 12:31
    
@Stephanie +1 good additional info, thanks –  Linker3000 Jul 16 '11 at 13:42
    
@stephanie-- thanks for the information. Put that in as your answer and I'll choose that as best. –  Jim Syyap Jul 17 '11 at 0:36
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Did you actually do the paperclip test properly?

Getting nothing could mean the PSU is dead or the paperclip test wasn't done properly. It's impossible for us to say.

But it sounds like the PSU isn't dead if the fan was activated and a LED was on.

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It's inconclusive then. I guess I am going to have to swap out that psu to get that ruled out. Thanks! –  Jim Syyap Jul 16 '11 at 20:48
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