Dead Mobo ?

[Simon]

Hi There,

This is a customer job, originally the PC was powering down all on it's
own. After debugging this a new PSU was installed, PC was working fine.
Now 2 weeks later the PC won't power on at all. I have tried a brand new
PSU, still nothing - no lights/fans anything. I disconnected all the
peripherals from the mobo and also tried shorting the connectors on the
mobo where the power switch connects in case that had gone, still nothing..
I'm wondering if the previous power supply failing has introduced a
fault on the mobo/cpu that has taken this long to show ?
Any replies appreciated.
thanks simon.

 

[Mike T.]

Hi There,

This is a customer job, originally the PC was powering down all on it's
own. After debugging this a new PSU was installed, PC was working fine.
Now 2 weeks later the PC won't power on at all. I have tried a brand new
PSU, still nothing - no lights/fans anything. I disconnected all the
peripherals from the mobo and also tried shorting the connectors on the
mobo where the power switch connects in case that had gone, still
nothing..
I'm wondering if the previous power supply failing has introduced a fault
on the mobo/cpu that has taken this long to show ?
Any replies appreciated.
thanks simon.

It's not unusual for a failing power supply to kill and/or weaken connected
components. I think you are seeing a delayed reaction to the original power
supply failure. Good bet the mainboard is toast. -Dave

 

[Israel Richner]

Sounds like your on the right track, I would just check the red voltage
switch on the back of the power supply before replacing the mobo. I
think the settings are 220 and something else.

 

[Rod Speed]

This is a customer job, originally the PC was powering down all on
it's own. After debugging this a new PSU was installed, PC was
working fine. Now 2 weeks later the PC won't power on at all. I have
tried a brand new PSU, still nothing - no lights/fans anything. I
disconnected all the peripherals from the mobo and also tried
shorting the connectors on the mobo where the power switch connects
in case that had gone, still nothing.. I'm wondering if the previous
power supply failing has introduced a fault on the mobo/cpu that has taken this long to show ?

Yes, that is certainly possible. Power supplys dying can over
voltage the output rails and that can produce that sort of effect,
a delayed failure of what was powered from the original supply.

Another possibility is that the motherboard was bad when it first
showed up at your place, and that fault saw the original power
supply shut down as its supposed to when the load on one of the
rails was too high. The second power supply could supply more
current on that rail and so didnt shut down, and then the original
motherboard fault developed into a permanent failure.

The obvious test between these two possibilitys is whether
the original power supply still works or not, but there is some
possibility it may kill what you test it with if its intermittent.

 

[Simon]

Another possibility is that the motherboard was bad when it first
showed up at your place, and that fault saw the original power
supply shut down as its supposed to when the load on one of the
rails was too high. The second power supply could supply more
current on that rail and so didnt shut down, and then the original
motherboard fault developed into a permanent failure.

The obvious test between these two possibilitys is whether
the original power supply still works or not, but there is some
possibility it may kill what you test it with if its intermittent.

Thanks all for the replies
simon