Foxconn WinFast NF4K8MC power up problem

[llphat]

I have a Foxconn WinFast NF4K8MC motherboard which does not seem to power up if you short the PWR_SW leads. If you however short the PS-ON (green wire on ATX power connector) to ground it will power up and boot without problems. Once powered up, you can switch the board off by shorting the PWR_SW lead for a few seconds, after switching off though it will again not power up if you short PWR_SW, the only way to power up is to short the PS-ON to ground on the ATX power connector.

Yes I can probably make two switch, one to hot-wire PS-ON to ground to start and the other is the normal switch connected to PWR_SW but it's rather annoying.

Any clues of what might be wrong? Thanks.

[Krankshaft]

Did you try another power supply?

ATX PSUs have a power good signal (gray wire) they output through the ATX connector if it's not there the mobo may not power up unless you force it directly. A power good signal won't be outputted until all of the rails are within voltage spec.

[llphat]

Thanks for your response.

I had tried at least two different PSU, with them having either 24pin or 20pin power connectors but the effects are the same.

[ala_borbe]

you can try replacing the ITE chip. it is responsible for power on

[czeq]

Originally Posted by ala_borbe

you can try replacing the ITE chip. it is responsible for power on

how easy replacing this chip, i have EXACTLY same problem, with same motherboard, one day it stop power up, and i have to use wire to power it up manually, connecting green and black wire.

[kc8adu]

i dont think its getting that far.no pg on +5stby.
something on the board may be telling the system the +5stby is out of range and this blocks startup till you force it on.

Originally Posted by Krankshaft

Did you try another power supply?

ATX PSUs have a power good signal (gray wire) they output through the ATX connector if it's not there the mobo may not power up unless you force it directly. A power good signal won't be outputted until all of the rails are within voltage spec.

[Calchaqui]

Originally Posted by llphat

I have a Foxconn WinFast NF4K8MC motherboard which does not seem to power up if you short the PWR_SW leads. If you however short the PS-ON (green wire on ATX power connector) to ground it will power up and boot without problems. Once powered up, you can switch the board off by shorting the PWR_SW lead for a few seconds, after switching off though it will again not power up if you short PWR_SW, the only way to power up is to short the PS-ON to ground on the ATX power connector.

Yes I can probably make two switch, one to hot-wire PS-ON to ground to start and the other is the normal switch connected to PWR_SW but it's rather annoying.

Any clues of what might be wrong? Thanks.

Same problem in several mobos, ghetto fix soldering a direct swich. I cant fully understand the root problem

[Calchaqui]

Originally Posted by ala_borbe

you can try replacing the ITE chip. it is responsible for power on

One of the mobos with this failure, a Biostar one, has no ITE CHIP whatsoever, it doesnt even has little transistors or discrete components (rersistors, caps) in the PSON trace to atx connector. It is quite clear.
A MISTERY to me (it powers up directly, but not using the pson panel pins, but powers downs using the pson panel pins)
Any comment?

[ala_borbe]

you can read here some basic info about SIO and how it works

http://translate.google.com/translat...hoat-dong.html