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Technical News & Discussion => Windows News & Discussion => Topic started by: psp83 on Oct 20, 2008, 12:12:52

Title: Computer problem
Post by: psp83 on Oct 20, 2008, 12:12:52
Well the PC downstairs stopped working yesterday. I thought it was the PSU but the mobo has the green light on.

What could stop the PC powering up? pressing the button on the front doesn't do anything.

Motherboard dead?
Title: Re: Computer problem
Post by: Rik on Oct 20, 2008, 12:14:29
No beeps, Paul? If so, check for anything shorting the mobo to the case.
Title: Re: Computer problem
Post by: psp83 on Oct 20, 2008, 12:16:36
Quote from: Rik on Oct 20, 2008, 12:14:29
No beeps, Paul? If so, check for anything shorting the mobo to the case.

Nothing at all. everything seems dead except for that one green light on the mobo.

I took it all apart and put it back together. still the same.
Title: Re: Computer problem
Post by: Rik on Oct 20, 2008, 12:17:26
Is the PSU delivering power on all the rails?
Title: Re: Computer problem
Post by: psp83 on Oct 20, 2008, 12:19:27
dunno. not got a voltage checker, my one is broke.
Title: Re: Computer problem
Post by: Rik on Oct 20, 2008, 12:20:53
All you can do, then, is try a spare PSU if you have access to one. If it still won't work, it's probably the mobo. :(
Title: Re: Computer problem
Post by: psp83 on Oct 20, 2008, 12:24:32
well i was thinking about getting a package from novatech or something and turning the pc into a server as its quite old and i dont think i can get a mobo that will support the celeron cpu.
Title: Re: Computer problem
Post by: kinmel on Oct 20, 2008, 12:35:37

You can check if the power supply will jump start whilst disconnected from the motherboard by following this guide (http://forum.overclock3d.net/showthread.php?t=435).

If the p/s fan doesn't spin up then the supply is duff, if it does start then follow this flowchart (http://www.fixingmycomputer.com/)
Title: Re: Computer problem
Post by: Sebby on Oct 20, 2008, 19:02:28
Have you tried removing the power plug from the PSU and putting it back? Sometimes it "resets" things.
Title: Re: Computer problem
Post by: psp83 on Oct 20, 2008, 21:00:40
First thing i did, plus checked to see if power was going through the mains cable and it is.
Title: Re: Computer problem
Post by: LesD on Oct 20, 2008, 21:17:28
Quote from: kinmel on Oct 20, 2008, 12:35:37
You can check if the power supply will jump start whilst disconnected from the motherboard by following this guide (http://forum.overclock3d.net/showthread.php?t=435).

If the p/s fan doesn't spin up then the supply is duff, if it does start then follow this flowchart (http://www.fixingmycomputer.com/)

The guide is worth a  :karma: Alan so have one on me.

I have had a modicum of success on at least one occasion by giving the PSU fan a spin while pressing the PC's on button. Sometimes the back emf this creates can make a difference but if it does work the PSU is definitely on the way out.
Title: Re: Computer problem
Post by: psp83 on Oct 21, 2008, 15:28:16
is this voltage tester good enuff for computers?
http://cgi.ebay.co.uk/PRO-DIGITAL-MULTI-METER-VOLTAGE-VOLT-TESTER-TESTERS_W0QQitemZ110301761505QQcmdZViewItem?hash=item110301761505&_trkparms=72%3A1301|39%3A1|66%3A2|65%3A12|240%3A1318&_trksid=p3286.c0.m14 (http://cgi.ebay.co.uk/PRO-DIGITAL-MULTI-METER-VOLTAGE-VOLT-TESTER-TESTERS_W0QQitemZ110301761505QQcmdZViewItem?hash=item110301761505&_trkparms=72%3A1301%7C39%3A1%7C66%3A2%7C65%3A12%7C240%3A1318&_trksid=p3286.c0.m14)
Title: Re: Computer problem
Post by: Rik on Oct 21, 2008, 15:36:19
Probably, Paul, but there's not a lot of information there.
Title: Re: Computer problem
Post by: psp83 on Oct 21, 2008, 15:37:52
what should i look for in a voltage tester for a pc?
Title: Re: Computer problem
Post by: Rik on Oct 21, 2008, 15:44:00
I'd want to know the accuracy for starters. :)
Title: Re: Computer problem
Post by: psp83 on Oct 21, 2008, 15:46:55
Doesn't say that on any i've seen, including amazon.

What should the voltage be anyways? i've forgot, been along time since something like this has happened.
Title: Re: Computer problem
Post by: Rik on Oct 21, 2008, 15:59:30
You really want good performance at low voltages. My Fluke gives a 40V scale with a resolution of 0.01V and an accuracy of +/- 0.9%, and a 4V scale with a resolution of 0.001V, same accuracy.
Title: Re: Computer problem
Post by: kinmel on Oct 21, 2008, 16:14:38
Quote from: psp83 on Oct 21, 2008, 15:37:52
what should i look for in a voltage tester for a pc?

I use one of these (http://shop.ebay.co.uk/?_from=R40&_trksid=m38&_nkw=power+supply+tester)
Title: Re: Computer problem
Post by: Rik on Oct 21, 2008, 16:17:35
How do you find them, Alan? Are they sufficiently accurate to diagnose a fault, or simply adequate to test if something is working at all?
Title: Re: Computer problem
Post by: kinmel on Oct 21, 2008, 16:54:46
Quote from: Rik on Oct 21, 2008, 16:17:35
How do you find them, Alan? Are they sufficiently accurate to diagnose a fault, or simply adequate to test if something is working at all?

Works fine, just plug the P/S in and watch for the green lights.

They just pass or fail each rail. 

You need much more serious kit if you want to start repairing/replacing board components though.

Is it worth all the effort though? Power supplies are cheap enough to just throw away these days

Title: Re: Computer problem
Post by: Rik on Oct 21, 2008, 16:57:17
So are a lot of computers, Alan. ;)
Title: Re: Computer problem
Post by: kinmel on Oct 21, 2008, 17:12:19
Quote from: Rik on Oct 21, 2008, 16:57:17
So are a lot of computers, Alan. ;)

Well as long as it's not an Apple replacement parts are cheap enough, but then you miss an opportunity to upgrade of course  :thumbd:
Title: Re: Computer problem
Post by: Rik on Oct 21, 2008, 17:38:06
Real men don't eat quiche, eh? ;D
Title: Re: Computer problem
Post by: psp83 on Oct 23, 2008, 18:58:59
I guess the mobo has died.

I've tried the jump start psu thingy and the fan started up.
(http://www.psp83.com/pics/jumpstart.jpg)

The PSU tester also showed the +12v green light.
Title: Re: Computer problem
Post by: Sebby on Oct 23, 2008, 19:06:54
It does sound like it, Paul. Still, they seem to be fairly cheap these days.
Title: Re: Computer problem
Post by: Steve on Oct 23, 2008, 19:37:59
If PSU is ok , is the case power switch working?
Title: Re: Computer problem
Post by: Colin Burns on Oct 23, 2008, 20:05:56
probably the eaiest way to find out if it is would be to trace the switches cable back to the board and bridge the gap with a wire/paper click. to make it think the switch is there.

Title: Re: Computer problem
Post by: Steve on Oct 23, 2008, 20:11:04
Absolutely, I have used a screw driver in the past to bridge the gap
Title: Re: Computer problem
Post by: Glenn on Oct 23, 2008, 20:44:44
The fan runs off the 12v rail, most, if not all the motherboard run off the 5v rail, which then gets converted to 3.3v or less for the components.