How can I test a power supply?

[horqua]

I'm rebuilding a PC that originally died due to excessive heat build-up. I've replaced both the chip and mobo. When I hit the power switch, power comes on, I can hear the HD spinning, the system seeks the keyboard, HD, CDR, and floppy but nothing appears on the monitor and no booting occurs. No BIOS startup, no video whatsoever. A friend suggested the problem may lie in the power supply. I've tried a second PS but I get the same results. I've also checked the mobo battery and reset the bios jumper for a fresh start.

Here are the particulars:
mobo = Biostar P4VMA-M with built in Video, network, sound. I'm using the built-in video but have tried both an AGP and PCI card with similar results.
Chip = CeleronD 2.5g
PS = Emachines

Suggestions are welcomed! Thanx

Knock and the door will be opened to you; Seek and you will find; Ask and it will be given to you!

 

[Gloryhound]

Sounds like the main board has gone into protection. This could be because the board is improperly installed or there is a short somewhere. It could also mean your video is having problems.. Does the mobo make any beeping sounds on boot?

 

[rvnguy]

horqua,

You can quickly eliminate/tracs what the problem might be by removing the mainboard and setting it on an insulated surface(newspaper will sufice) and trying to boot.

I assume that you were not receiving a POST Beep. If by doing this you get a POST beep and video etc. you have determined that there is a short of some type. Check your standoffs, for crossing a trace or the like, also where the holdown screws touch the mainboard.


rvnguy
"I know everything..I just can't remember it all

 

[Frank4d]

Check the floppy drive and see if the activity light is on continuous. If so the floppy cable is plugged in backwards.

Also, as rvnguy suggested, you could have a short. Check to make sure the case has standoffs for each MOBO mounting hole... and that there are no other standoffs.

 

[garebo]

Do you have all the connectors connected? Like the 4 pin 12 volt connector for P4? Sorry, have to ask.

I dont think the problem is the power supply being as you have tried 2 different ones, but you did ask about how to check out your power supply, so here goes.
You need a digital or analog multimeter, (digital is best), which are available at big box hardware and other hardware and auto stores. Then you can go to techrepublic where you will find a great tutorial on how to check each line (rail) for correct voltage. You do have to sign up, but its free and a great site anyway. That is about the only way i know of to properly check a power supply. The tester that you can get at best buy and such will only test if the ps is turning on or not, but thats not close to good enough for testing.

Good advice + great people = tek-tips

 

[rvnguy]

horqua,

Yes, I appologize for reading around your posted question and digging into what I thought your problem might be while ignoring your actual Posted query.

Thank garebo for picking up on this and providing his excellent advice on true complete PS testing.


rvnguy
"I know everything..I just can't remember it all

 

[garebo]

Thanks, rvnguy, for the kind words. Actually, though, i believe you also gave good advice, based on what the problem seems to be. I had the very same happen today on a system that came in to me. I used my pci diagnostic card and it pointed to the cpu. Sure enough, i replaced the cpu and all is well.
I suppose one other thing to check would be to make sure the cpu you are using is ok for that mobo. That is, if you havent had the system running at all yet.
And of course double and triple check all your connections.
In the end, if you still cant get it to boot, do take the mobo out of the case and try booting with on the minimum needed, talking out all pci cards except video if needed, unhooking any usb not needed, and so on.
You mentioned you reset the bios. Did you read the manual on how to do so as some motherboards differ from others, some want the power connected for a bios reset and some dont.


Good advice + great people = tek-tips