PC won't boot properly - power OK

[Tim Synge]

I have a Pentium II which has worked fine for some years. All of a
sudden, it will not boot up.

Here's what happens.

When I turn on the power and switch the PC on, both fans (CPU and power
supply) come on fine. The power LED on the PC lights up. I am 99.9%
sure that the hard drive starts spinning. There is a little series of
clicks as if the heads are starting to read the hard drive. So far so
good. The CD-ROM drive seems to be fine - it accepts a disk and sets
it spinning.

Here's what doesn't happen.

The characteristic "beep" that follows the initial reading of the hard
drive doesn't happen. There is no floppy disk drive activity (I cannot
boot from my "rescue" floppy.) The system doesn't boot up at all. There
is "no signal" to the monitor. (Therefore no evidence of scrolling
through the various hardware/RAM tests etc prior to loading Win98.)

The computer just sits with the fans gently humming until I remove the
power again.

I have opened it up and checked that all plugs and connectors that look
as if they belong somewhere are firmly bedded. No change.

The only thing that might be remotely relevant is that this started
almost immediately after I had been using my printer with a different
PC, then reconnected the printer to this PC. Each time I tried to
connect the printer to this PC, Win98 would simply freeze completely.
This very quickly developed to the situation I have described.

I have previously been advised to run some hardware diagnostics.
Unfortunately, "PC Doctor" (?) is sitting happily on the hard drive,
but completely inaccessible in the current situation.

All suggestions welcome ...

Tim

no spam please

 

[Jan Alter]

Hi,
I'm listing some options for you to try.

Observe capacitors on the mb and look for any leaking electrolyte on their
tops or on the board. (mb is no longer viable)
Make sure the graphics card is seated firmly in its slot.
Disconnect all peripherals such as CD-ROM, hard drive, floppy. Disconnect
printer cable. Do not remove graphics card.
Try booting and listen for Post.

If none check cmos battery. It should be 3 volts, minimum 1.5 . Also clear
cmos (usually by temporarily moving a jumper)
Additionally, reseat RAM

Further, it's still possible the PS is a problem, and you can either check
voltages with a multimeter or simply substitute a know good PS and try
booting.

That all done it's possible the mb has collapsed

 

[w_tom]

If the foundation is collapsing, everything else in a
building can have strange problems. Same with a computer.
Very first thing to check is power supply (computer's
foundation), using two minutes, and 3.5 digit multimeter. In
your case, voltages on the red, orange, yellow, and purple
wires are important. Voltage must be above 3.22, 4.87, and
11.7. If not, the computer will do strange things. Also
voltage on gray wire must maintain significantly more than 2.4
volts - else computer will lock.

Can PC Doctor (or DOS) be booted from a floppy? Another
important symptom.

Very few - almost no failures - are visually apparent. The
system may have been failing for so long that bad capacitors
are visually apparent. But if the system is problematic, and
everything previously suggested does not help, then strip the
machine down to basic components to learn what does and does
not work. Basic as in keyboard, mouse, video controller and
display, CPU, RAM, power supply, floppy drive (if bootable
floppy is available), and speaker. Now what happens?

 

[DaveW]

It sounds like either your PSU or your motherboard have failed. The easiest
thing to try to diagnose which is to replace the PSU with a known working
one. If that doesn't fix it then it's probably the motherboard.

 

[itsacin]

I've had a similiar problem with my computer. Usually happens after a
power surge or failure of some type. My solution was to unplug anything
not absolutely nessesary, like the cd roms and dvd players. Unplug the
power of course first then clear the cmos jumper. With mine its simply
a jumper that is moved to the clear settings for a few seconds. I'd
check your motherboard guide. This takes me right to the bios settings
and it's usually the cpu setting that is reset preventing it from
operating. Check your utilities settings and reset anything that may
need it.
Hope this works for you.

 

[w_tom]

Dave is discussing "PSU or your motherboard have failed".
That being a hard failure. You are confusing that with what
sounds like the protective lockout located on motherboard. A
protection feature that is reset - not a hard failure - when
power cord is removed from the wall.

 

[Tim Synge]

Thank you all for your suggestions. Got it back up yesterday - I don't
honestly know what I did differently from the previous 100 attempts,
but it sprang into life, ran Scandisk and sat there as if there had
never been a problem. I even managed to get the printer plugged in
without the PC immediately freezing again.

I ran PC Doctor, which suggested nothing amiss. My intention is now
simply to leave the PC switched on (hoping there aren't any crashes
that might result in a reboot being necessary) until I identify a
suitable replacement (which for various reasons is due this winter
anyway). I appreciate all the helpful advice and suggestions though.

 

[w_tom]

This is the time to be taking voltage readings with the 3.5
digit multimeter. First with system in idle. Then again,
when multiple devices are being accessed at the same time.
IOW soundcard playing music, as hard drive directory is being
displayed, as floppy disk is read, and a DVD is playing - or
even better burning - and then record those voltages.

Also review historical error messages in the Event (system)
logs. If unknown, learn about event logs in Windows Help.