Testing Power Supply

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Rickles

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#106439 24-Jul-2012 12:37

Folks,

I have a desktop that will not fire up .... the little green light on the motherboard comes on, but when the start button is pushed the CPU fan spins once, and nothing more happens.

As a test, I have connected a new power supply to the motherboard via the 24-pin connection, and the CPU fan connection .... again the green light comes on but nothing else including the PSU fan?

Any clues or ideas would be welcomed,

R.

xpd

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#660966 24-Jul-2012 12:44

We get a few like that, usually find that a cap has given up on the board.

Remove everything from the board (RAM/HDD etc) and try again, reset CMOS.... if still no go, think itll be time to look for a replacement.

XPD / Gavin

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Rickles

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#660968 24-Jul-2012 12:49

Gavin,

Thanks ... yeah, bare board testing was our next thought too.

I presume that all circuits need to be formed before a PSU's fan comes on, or will that run with just external power?

R.

Rickles

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#661507 25-Jul-2012 10:01

UPDATE:

I used a power supply tester on the spare PSU I have, and with just the 24-pin connection all the testers' lights came up solid and the fan was running.

Connecting the suspect PSU to the tester, all lights very briefly flashed and then only the +5VSB light stayed on.

Would that tend to indicate that indeed the PSU is buggered?

R.

LostPacket

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#661519 25-Jul-2012 10:25

what power supply tester are you using?

Rickles

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#661520 25-Jul-2012 10:29

Power supply tester is just one of those off TradeMe (Chinese origin?), .... not exactly up to to commercial/industrial standards I know, but seems to do the job when I tested the various connections with the good power supply.

R.