SM schrieb:
> Hi all,
> my Asus P3B-F motherboard doesn't start at all.
So, did you try another PSU now?
> When i plug the power cord i see the internal LED green.
> I checked all the ATX power supply connector pins: all the voltages are
> present but the PowerGood signal is low.
From the ATX power supply design guide v2.01, as found on
formfactors.org:
> 3.3.1. PWR_OK
> PWR_OK is a ´power goodˇ signal. It should be asserted high by the power supply to
> indicate that the +12 VDC, +5VDC, and +3.3VDC outputs are above the under-voltage
> thresholds listed in Section 3.2.1 and that sufficient mains energy is stored by the converter
> to guarantee continuous power operation within specification for at least the duration
> specified in Section 3.2.11, ´Voltage Hold-up Time.ˇ
[That's 17 ms.]
> Conversely, PWR_OK should be deasserted
> to a low state when any of the +12 VDC, +5 VDC, or +3.3 VDC output voltages
> falls below its under-voltage threshold, or when mains power has been removed for a time
> sufficiently long such that power supply operation cannot be guaranteed beyond the powerdown
> warning time.
So since you apparently managed to turn on the PSU but PWR_OK is low
nonetheless (which in turn tells the board that it better not power up),
I'd say that the power supply is defective. (If it's as old as the board
or older, it may simply have dried-out caps. But given that you can buy
good, solid PSUs like the Fortron Source FSP300-60PN for not too much
money, a repair is hardly worth it.)
Stephan
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