3.5 year old Dell. Won't power on, supply fan doesn't spin.
Pulled supply & it powers up outside the PC. (10 ohms between
any red & black wire; green wire shorted to black for testing
outside the PC). Pulled everything from the mobo (motherboard)
one thing at a time, still won't power up. Tested PC power on
switch with ohmmeter - tests good. No shorts at power connector
pins (ohmmeter), no visible burns, no swelled lytics. Was working
a week ago.
Anyone have any thoughts on what else I can check?
Note: below refers to standard psus- you don't say the model of your
Dell - which may not have standard pinout/colour coding
Here's what I would do:
1) Ask at a pc hardware group with the model number - ideally a Dell one
- in case the pinout or colour code is different..
2) Disconnect all the output leads from the power supply
3) connect a dummy load (some psus wont work (reliably) without a
minimum load) - I use an old 20MB (yess 20 meg) disk drive).
4) Check the mains power lead on a different appliance.
5) plug in mains power lead.
6) Check for standby 5v power between pin 9 (purple) on ATX connector
and ground (any black) - no power, psu is faulty.
7) Start up main power supply by shorting pin 14 (green) and ground.
8) CHeck for volts at the disk drive connectors/other connections -
If all the above is ok - the mobo is probably dead.
If not ok - the power supply is dead.
Reconnect switch, power supply, and motherboard. Best test is all
components of the power supply system united, undisturbed, and loaded
by the computer. Follow the two minute procedure posted in "When
your computer dies without warning....." starting 6 Feb 2007 in the
newsgroup alt.windows-xp at:
Best and informative test means power supply remains connected rest
of power supply 'system' and to a full load - the computer. According
to that procedure, first measurement with a 3.5 digit multimeter would
be a purple wire from power supply to motherboard - both before and
when power supply switch is pressed. Other important numbers are
voltage on green and gray wires. And finally what happens to voltages
on orange, red, and yellow wires when power switch is first pressed.
Lower limit numbers are 3.23, 4.87, and 11.7. But based upon what was
reported, the problem probably will be apparent long before getting to
that orange, red, and yellow measurement.
Best testing does not remove anything. Reporting those numbers here
may provide more useful facts that are otherwise not apparent. Chance
are the problem will be apparent with the purple, green, and gray
wires before and when power switch is pressed.
It is now fixed. Bad motherboard. What a pain - the new
mobo required a new cpu, new cooling fan/sink and new memory
and it wasn't just a "drop in" replacement. Windows had to be
re-installed, as the new mobo and the existing Windows on the
hard drive would not work together. So I bought a new HD,
installed Windows on it and copied the data over from the old
HD. I spent a day reinstalling Windows, downloading and installing
all the Windows updates, then reinstalling all the programs,
downloading drivers & installing, etc. etc. A "nice" extra
pain in the ass was that the FDD header on the new mobo
did not match the floppy drive ribbon cable.
Anyway, its a much faster mobo/cpu, and now the C: drive
is 320 gig SATA (vs the old 80(?) gb ide) so its a nice
Thanks to those who replied.
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