Switching On Problem.


Apr 21, 2001
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The best thief you'll never see.
For a few weeks I have been having to press the button on the PC case a few times after plugging it in before I could hear power sparking the PC up.
Then for about 3 days I have to leave the power on to the machine a couple of minutes before pressing the case button. This morning it was like 5 minutes or more before the button would spark the PC up.

It looks like a deterioration problem and at some stage is not going to switch on at all.

Does anyone know what component is that could be causing the problem? And if something like a faulty capacitor where would it be, i.e. case, power unit, MB etc.
I had a similar fault where the PC wouldn't power when pushing the button but it was intermittent. Sometime is worked first try then next it would take half a dozen tries and sometime even longer.

Once booted there was no problems.

Put it into local shop and they had it a couple of days but couldn't replicate it - they were about to give me it back and did the last couple of tests only to experience it.

They advised it was a fault on the PSU - it's been swapped out and has been fine since then.
Yeah faulty PSU sounds right, they store power to smooth out the supply so this maybe not working hence the 'warm up' time.

Given the "charge up" time, my guess would be a faulty CMOS battery.

If the CMOS battery is dead most systems won't boot. However, some systems maintain a short backup charge for the CMOS which is supplied by the PSU +5Vsb (standby power line). If you turn off the PSU at the plug then this voltage isn't maintained and the backup for the CMOS battery will drain quite quickly. When you turn on the power the +5Vsb is restored and the backup begins to charge, eventually the system will boot.

It's worth replacing the CMOS battery. Certainly much cheaper than replacing the PSU.

Oh, and BTW, PSU's don't store power to smooth out the supply. A mains conditioner, or better still a UPS, is required for that.
Just got a battery this morning but it will be a week I think before I try that solution incase things go belly up. I need the net up without fail for a week.

Thanks all for the advice. If the battery fails I think I'll get a new powersuply with a eye on the future for upgrades although the last SU Im very pleased with a Hype Type R:smashin:
Oh, and BTW, PSU's don't store power to smooth out the supply. A mains conditioner, or better still a UPS, is required for that.

Perhaps not smooth out the supply exactly but they do store power hence all the warnings about opening them.

The CMOS battery can be ruled out if the PC doesn't hold the time and date.

Well the up shot was the PC would not start the day before I was ready to sort it out(typical). anyway the quickes thing was was the CMOA battery but that did ot work.
Then I remebered I still had a power supply unit that was still working but not powerful enough to work the graphic card, I tryed it and it got a lot further.

So I too it back to the suppliers unfortunatly the 3 year garentee was back to base after a year so I bough a new one and Im going to send the faulty one of for repair or exchange.

Oh the new PSU did the trick.

Thanks again for the help:smashin:

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