glend0 said:
hi. my problem is when i updated my pc (windows xp). after it had updated and
i needed to restart my pc. but before i restarted it my electricity went off
now when i start my pc nothing happens my screen is blank. i have tryed f8
ect,ect. restarted with xp disk in. still nothing. please help. its driveing
me nuts. thankyou
The most probably answer, may depend on the brand and model number of the
computer. There are some Emachines, for example, where a power supply failure,
ruins the motherboard (so two components fail at the same time). On other
machines, it could be a single component has failed, with the power supply
still being a candidate. The AC input to the supply is exposed to all the
outside world insults, such as spikes, brownouts and so on.
Have you tried turning off the switch on the computer, unplugging the power
cord for a short time (60 seconds minimum), then plug it in and try again ?
Do any power lights show up, as they normally do ? Some power lights
run from +5V. If you have a mouse and keyboard that are always powered,
even when the computer sleeps, then the light on the optical mouse could
indicate the +5VSB is working.
If the fan on the power supply is spinning, and the other ventilation
fans are running, you have +12V. And that would indicate that the power
supply is mostly working.
If you got the fans to spin, that means pressing the soft power button on
the front of the computer is working. The next step, would be to consider
what other parts inside might be broken.
The BIOS screens are a good way, to prove some of the system works. The
user manual may tell you which key enters the BIOS. I have a number of
computers here, where I use the <Delete> key to enter the BIOS. I have
one machine where you press F2 to enter the BIOS. If you can enter
the BIOS, and see the 640x480 text screen, then the processor and RAM
are working to some extent.
When you look in the BIOS screens, there is a section for IDE disks,
You don't need to change the settings, but you can look to see whether
the brand and model number of your hard drive is listed. That tells
you the BIOS can do a simple communication with the disk. And the disk
will not identify itself, unless the internal initialization sequence
completed. Some disk failures, cause the disk controller to refuse to
answer any probes, even though the disk may be mostly functional
(from a mechanical perspective). The industry design intent seems to
shun the idea, that the disk controller (logic board), should be
able to tell you things, even if the platters don't spin.
Another diagnostic approach, is to simplify the setup. If you had
a graphics display, but only a flashing cursor, you could try
powering off using the switch on the back of the computer,
and disconnecting components not essential to getting the BIOS
to work. You could strip the RAM down to just one stick (if there
are multiple sticks). You could disconnect the ribbon cable(s) to the
disks, keeping careful note of the orientation and which end is
which and so on.
I had one machine, where one day I could not get into the BIOS.
The fans on the machine were spinning, but the screen was black,
and there was no beep. I had two sticks of RAM, and I tried them
alone, one at a time. With one stick present, the machine
started. The other stick caused the computer to "black screen".
Some RAM faults are serious enough, that the BIOS cannot
send a "beep error code" to the speaker. It turns out, the
defective module had one chip which was entirely dead. That
means a lot of low memory locations wouldn't be working properly,
which is where the BIOS stores its working data.
Finally, if you remove all the RAM, many computers will beep
the "RAM error". The fact that the computer can beep the "RAM error",
is still an indication that a good percentage of the motherboard is
functional. So you can use the expectation of a "beep code",
as a test that the processor worked well enough to emit a beep.
If the BIOS contents were damaged for some reason, then the computer
may not beep. And simplifying, by disconnecting stuff, wouldn't
make any difference. So you can get to a point, where it is time
to consider replacing the motherboard. But by the time you get there,
it might be a good idea to get out the multimeter, and verify the
power supply voltages. Just in case there is an obscure fault there.
And at that point, you might want some help from a shop. Ask for a
price on a diagnosis, and when they tell you which component they
think has failed, you can take it from there.
The problem with some prebuilt machines (Dell/HP/Gateway), is
deciding what to do next. One of the reasons I build my own computers,
is so I know the answer to this question (by not buying pre-built, I
can replace components modularly, without having to worry about the
screwy OS they installed).
Good luck,
Paul
