[Gllug] Hardware fault

Chris Bell chrisbell at 3966.ukfsn.org
Tue Apr 13 11:40:54 UTC 2010

On Mon 12 Apr, Dylan wrote:
> Hi All,
> I am faced with a machine which is *completely* un-responsive after power-up. 
> There is no HD activity, no activation of the monitor from standby, and no 
> beeping, although the fans run normally. I have removed or disconnected 
> mouse, keyboard, DVD and HD (both SATA) and memory resulting in no change of 
> response - i.e. there is no complaint of any kind about the lack of essental 
> hardware. The machine's owner tells me that yesterday it spontaneously 
> rebooted.
> Is there any way simple way to distinguish a power supply, processor or 
> motherboard fault? Any suggestions would be welcome.
> Dx

   Not all ATX PSU connectors are standard layout, but usually totally
disconnecting the PSU from the computer and then applying mains will give +5
volts standby on one pin only plus another just under +5 volts (often a
green wire) to drive full power-up when connected to any 0 volts (normally
black wires). I use a cut paperclip to connect the start volts pin to 0
volts. Motherboards will link the +5 volts standby to a selection of PCI,
USB, and fan connectors, and even hard discs, ready for start-on-lan or
other triggers. USB connectors are easily damaged so that they short out
this standby supply, and then the computer does not power up. Voltages
off-load may not be exact but should be close to normal.

Chris Bell www.chrisbell.org.uk (was www.overview.demon.co.uk)
Microsoft sells you Windows ... Linux gives you the whole house.

Gllug mailing list  -  Gllug at gllug.org.uk

More information about the GLLUG mailing list