How do I test for faults?

[TheReaper]

Hi all, I just tested my PSU and it is working so next is what? The power switch? Mobo?

What should I test next and how?

 

I know the PSU is ok as I replaced it and tested it with a paper clip and chasis fan.

 

But when I install it and press the power button nothing happens.

 

Please help

[xtremedesign]

are all the power connections in? not only the 24pin but the pcie ports on the board.

 

make sure the power cord is in.. lol

[TheReaper]

Lol.

 

I stripped it down and rebuilt it to make sure all connections were solid.

 

The PSU is definitely working and I just tried a new power switch and still nothing.

 

What's next? MOBO? How do I test that?

[kingdingeling]

The mobo might be shorting on the case, I'd take it out and just run it on the box...

[wevsspot]

The lack of an onboard power switch really hurts in situations like this. Any other power indicator lights on the motherboard that show the board is getting power at all?

 

Diagnostics of a bad board requires equipment that most of us probably don't have - relegating us to testing components one piece at a time. I know you tried the jump start method of your psu but that isn't a 100% effective check for making sure the psu is good.

 

Since the psu is the cheapest thing in your setup - I'd borrow one or dig out a spare and try that first. If that doesn't bring the system to life, then you are going to have to consider the cpu or motherboard.

 

Any noticeable bulging caps on the motherboard or visibly burnt traces?

[TheReaper]

I installed a tested new PSU and apart from a slight initial movement from the CPU fan by a couple of mm's there's no signs of power from the mobo whatsoever, no lights, sounds, nothing.

 

There's no noticeable bulging caps on the motherboard or visibly burnt traces.

[wevsspot]

Reaper,

 

I'm assuming that this system has worked before? Any overclocking or stuff like that going on before the rig decided to take a crap on you?

[TheReaper]

Hi Wevs, yes it worked for 2 years without any problems. No one ever tried overclocking this system it just stopped turning on one morning.

 

The PSU was clicking so I tested it and swapped it out with a 500w new PSU.

 

EDIT: I forgot to say it is not the system in my sig it is my daughter's eMachine 370.

Edited December 8, 2009 by TheReaper

[TheReaper]

Ok weird thing... Now when I plug in the power lead, without pushing the power button, the CPU fan is spinning constantly but no other signs of life, still no lights or beeps etc.

 

EDIT: I unplugged and plugged back in and the CPU didn't spin, then I unplugged and plugged in again and it spun again. I think the fan has a dirty/sticky spindle or something but it has power going to it through the mobo.

 

But still no power anywhere else.

Edited December 8, 2009 by TheReaper

[wevsspot]

Is it possible that the cpu fan has been failing/failed for a while and you just didn't know about it? Possible that the m/b - cpu overheated and burned?

[Crazy_Nate]

You can easily rule out the case switch (or any momentary switch that you're using), by simply shorting the two pins on the motherboard (they're often side by side, quite easy to do with a phillips head screwdriver).

 

I wouldn't be surprised if it was the motherboard. Personally, I'd take it out of the case (stick it on a piece of cardboard or other non-conducting material) and try it with bare minimums:

 

CPU, heatsink, new power supply (you might try the one from your rig - you know it works), 1 stick of RAM.

 

Reseat the CPU and heatsink (make sure there's no dust or anything). Don't use the old TIM, use some new AS5 or whatever you keep around. Remove memory, vacuum the DIMM slots, re-insert one DIMM. Jump the two pins for power to drain the motherboard (just for a second). Clear the CMOS (take the battery out if there aren't jumpers). If the battery is old, you can try a new one (you'd be surprised, sometimes it does really help).

 

Button things back up, make sure the jumpers are back in place and that everything is seated well, including power connectors. Flip the switch on the back of the power supply to 1 (note if any standby LEDs come on, etc), then short the two power pins on the motherboard (again, just for a second - you're doing the job of a momentary switch). It should power up and beep at you if something's wrong. If it just sits there, it's probably dead, but difficult to tell what component if you can't swap things out and test in another system.

[TheReaper]

Ok I stripped out the whole machine to the shell, cleaned out every component and reseated them all.

Tried a minimum hardware setup.

Still nothing.

I replaced the CPU fan with a new one but still nothing.

I did the jumping the two pins again, still no go.

It must be the motherboard.

I think it may be easier and more cost effective to build a new one. I built my other rig and it is great. I should never have got one built from a store lol.