Re: Power supply fried?

The message <kHIpzTDjN4NJFAio@xxxxxxxxxxxxxxx>
from GSV Three Minds in a Can <GSV@xxxxxxxxxxxxxxxx> contains these words:

Bitstring <wMHZk.1445$fw1.1056@xxxxxxxxxxxxx>, from the wonderful person
Gary S <jjj@xxxxxx> said
Rebooted my pc tonight and got no picture and no power to keyboard just a
flashing hard drive light continous.

Reseated vga card just in case but then that wouldnt cause a loss of power
to the keyboard?

Would a faulty PSU cause this?

Possible, but so could other things. If you have a spare PSU by all
means try it...

I've seen a similar system problem (I can't recall whether it was the
HDD activity LED for certain) which turned out to be the consequence of
a card reader acting as a bridge between the 5VSB rail and the 5V rail.
The simple cure was to rejumper the USB / PS/2 sockets power source from
the 5VSB line to the 5V line.

In this case, try disconnecting the card reader (assuming you have one)
from the internal MoBo USB header. Of course it might simply be an
overloaded 5VSB rail if you have a lot of self powered USB devices
connected and the MoBO is jumpered to supply from that rail instead of
the normal 5V one. And, of course, it might simply be that the PSU has
gone faulty or any number of alternative faults that can afflict PC
hardware.

The main thing here is to employ a systematic way to eliminate the
possible causes, starting with replacing the cheapest parts first after
you've disconnected all non essential items to eliminate any that might
be overloading the PSU due to a fault (this, in extremis, might include
the graphics card -you've got bios bleep codes to provide info-, ram and
the CPU fan (briefly) and even the CPU if the PSU starts looking more
and more a likely culprit.

This was the technique I used a couple of years ago on my own system to
get it down to a choice of MoBo or PSU before I _finally_ tried another
PSU and solved the puzzle (brief flash of the power on LED when trying
to start the machine the next morning after an uneventful shutdown the
previous evening).

I _so_ couldn't believe that a PSU could die overnight whilst it was
totally without mains voltage stress (I use the mains isolator switch
after a shutdown since it also shuts off the feed to the monitor and
speakers fed by the auxilary IEC power socket). Each time I shed some
load, the flash would become brighter and less brief.

I've just remembered, I've also seen similar symptoms when a clumsy
kack handed user has broken the the USB ports (Plural, please note!) and
placed a short circuit on the 5V feed either blowing the 3A polyfuse (or
smd inductor or circuit track in the case of PC Chips product) which
protects the USB and PS/2 socket power feeds.

If a polyfuse has been employed, simply clearing the fault will restore
service, otherwise, in the PC Chips MoBo case, you'll also have to
bridge the burnt out smd inductor or circuit trace.

HTH

--
Regards, John.

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