PC won't start!

W

wanstronian

Geek Trainee
Hi,

Tried to turn my PC on this morning and it's completely dead. I've ascertained using my multimeter that the switch is okay, which means it's either the PSU or the motherboard.

How can I find out which is faulty without actually replacing one or the other? The PSU fan doesn't spin, there's no life at all, apart from a little click inside the PSU when power is applied. I have checked the fuse on the power lead!!

We had a power cut the other day, but the multi-plug has a surge protection, so that shouldn't have blown anything up!

Thanks

W
 
http://pinouts.ru/data/atxpower_pinout.shtml
http://www.monarchcomputer.com/Merchant2/graphics/00000002/100298-pinout.jpg
take a look at those

short pin 8 and pin 14 if you have an atx 20-pin power supply to turn power supply on and it won't hurt anything if it's in working order, if you can use a multimeter to measure voltages that would be great.

be careful!

EDIT - actually hold up I did this to a power supply of mine in storage I'll go take a peek I think 8 and 14 may be wrong

EDIT - It's 13 and 14!
 
On my PSU those wires are labelled as 'Power Good' and 'Ground'.

Seems to make sense, but can you confirm?

And is pin order as follows?

01 02 03 04 05 06 07 08 09 10
11 12 13 14 15 16 17 18 19 20

or

01 02 03 04 05 06 07 08 09 10
20 19 18 17 16 15 14 13 12 11

with pin 1 in both cases being +3.3V?

Thanks
 
Okay - and you say short the pins, not just measure voltage across?

Sorry for all the questions, want to be absolutely sure I'm doing the right thing!
 
if you short the pins, and the power supply spins it's fans that's a start.
then you could use a multimeter to measure each individual rail, 3.3v 5v and 12v to make sure the power supply has correct volts going to the hardware
be sure it's not connected to any other hardware
 
Right then, I bought a new PSU. Plugged it all in and switched on the socket at the wall.

The PSU fan spins up as soon as power is supplied to it from the mains, and the HDD led is constantly lit. Nothing else happens and the switch on the front of the case has no impact.

I'm assuming the PSU took out one or more other components when it went, but can anybody give me a clue which ones to start testing/replacing first?

Thanks

W
 
Make sure all of the cards, the CPU, and the RAM, are properly seated. Remove them and reinsert them to be sure.



Remove all non-essential components and disconnect non-essential cables (including IDE, floppy, etc.). All you should need to reach the initial boot screen (memory count, etc.) are: the motherboard, CPU, RAM, power supply, and graphics card. If it boots, start adding components one at a time, and boot up each time. When the system won't boot, you've found your faulty (or incorrectly installed or incompatible) component
 
try shorting the 2 pins that the power sw on the front are connected to (briefly with a screwdriver or something (the switch could be dead)
 
Karanislove said:
All you should need to reach the initial boot screen (memory count, etc.) are: the motherboard, CPU, RAM, power supply, and graphics card. If it boots, start adding components one at a time...
Click to expand...
And if it doesn't boot to start with, it could be any of the components listed above. So are there any further diagnostic tests to identify which is the faulty component? Or is it a case of trying them all one at a time in another, known working system?
 
Check the power cord and outlet.
Check the power supply's connector to the motherboard. Disconnect and reconnect to be sure its firmly connected.

Check the power supply. If you can test it in another PC, try it. Axion Technologies sent along the following graphic to illustrate one way of testing whether or not an ATX power supply is functional:
jumperset.gif


Check the power switch on the PC's case and make sure it's properly connected to the motherboard. Try shorting the jumper pins that the switch uses to power on the PC. If that works, the switch is bad.
mbconnects-a.jpg

mbconnects1a.jpg

Make sure the motherboard surface is not making contact with the metal case (except at its mounting points). Take the motherboard and power supply out of the case and place them on a non-conductive surface (wooden table, etc.). If it boots, something was probably shorting out in the case
 
unfortunatly, you are correct, but as many or all of guys will probably agree, your best replacing the cheapest part first, i mean with my pc i recognise the smallest of things & alarm bells ring in my head, cos i've seem this before, and i go straight to that part & replace it
 
You mentioned that the light on the hard drive shines. What about the LED on the motherboard? That is a major giveaway as to the motherboards working state.

Does the CPU fan spin?

If it doesn't, then I would suspect a faulty motherboard. Assuming of course that everything is plugged in OK
 
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