Computer Won't Start!

[scroggs]

I've been resurrecting an old computer of mine for a mate, and it's suddenly decided to refuse to power up. It had been working perfectly, though the CPU fan was a little noisy. I had to change the CD drive, and when the machine was back together it got as far as the POST single beep (normal), then powered down. I suspected the power supply, and changed it for a known good one - same thing. There's no response to either the power or reset buttons; the machine attempts to power up on its own once the mains lead is connected and the power supply master switch is selected on. Once it's powered down, it will not power back up again at all unless the mains lead is removed for a few minutes. The CPU fan is working.

Any thoughts, chaps?

The tech stuff: it's a Pentium ll 333Mhz (slot 1) processor, QDI Legend V mobo, 128mb SDRAM, Matrox G100 graphics, AWE32 Soundblaster, Motorola V90 modem, Toshiba 32x CD, Zip 100 internal, 4Gb and 2Gb HDDs, Win98SE OS. As I said, old! (But all in good nick, and not heavily used).

Scroggs

[GoneWest]

Not heavily used!! - is that 'cos it won't start?? :D

[timmcat]

Scroggs,

I'm probably no more qualified than yourself to answer this, but, as they say, two minds better than one..

Presuming its not just coincidence, and that the drive replacement has something to do with it...

Have you checked the security of all the plugs / sockets
to and from the motherboard and all drives (annd re-checking the PSU connections in particular?

Have you another CD drive you can try.. perhaps the drive detection during boot is picking up a problem. Does the old drive allow boot to complete.

Was this an additional drive. If so, are the master / slave jumpers configured correctly?

I dont suppose (I don't see why you should have) you disconnected the HDD IDE plugs and got them 'mixed up'?

Hope this helps.

Tim

[scroggs]

The thing isn't powering up long enough to start checking drives etc. Even if the drives were wrongly configured, I should still get as far as the BIOS boot-up screen. The time from power-up to power-down is no more than 10 secs!

I also suspected that the removal of the CD may have been related, but, even with all drives disconnected there's no change. I'm beginning to think that there's a mobo or CPU problem, but I can't see why!

Scroggs

[Ronbmy]

Reset the bios.

And then try again.

Make sure you haven't dislodged the ram.

This effect can also be caused by the m/b not being securely fixed to the case. If the m/b moves then one of the mounting screws/pillars can short a trace.

[scroggs]

Um, how can I say this?:O

I'd had the front of the case off to replace the CD drive (and the replacement is t*ts up!!). On replacing the front, the power switch did not mate properly with the button on the case front, so with the front fully home the power switch was permanently depressed. Having disconnected everything, removed the mobo from the case and attached it to a PSU on the bench, all worked perfectly. Gradually rebuilt it in the case, and re-attaching the power switch lead to the mobo revealed the snag.

Just got to replace that CD again now. Ho hum.

Thanks chaps!

[timmcat]

Scroggs,

Nice one! We've all done something like that but how many of us are prepared to admit it!

Glad things all OK now.

Tim

[expedite_climb]

Scroggs,

Was just about to suggest it might be that !

Had a not dissimilar problem with a Master Caution button on a 757 a few months ago. It took 3 engineers 2 1/2 hours to spot why the fire warning bells werent working.... button stuck in !!