PC won't power up

  itw2 23:08 17 Jul 03

I had been suffering an intermittent failure to power up which finally resulted in my power supply failing with much smoke!! I replaced the power supply but although the LED on the main board lit nothing else worked. In desparation I took it to the local PC repairer who checked it over and concluded that a capacitor on the main board had gone. I have now replaced the main board with an ASrock K7VT2 but although I now get the main power on LED when I press the start button nothing else happens, no fan on the power supply, no processor fan and certainly nothing resembling boot up! Has anyone out there got any idea what is likely to be the problem? Thanks

  Mat2 23:25 17 Jul 03

Hi itw2

Have you looked on the back of the power supply to see if there is an on/off switch which some power supplies have it is like a master switch.


  jazzypop 23:30 17 Jul 03

Hmmm - very difficult to diagnose remotely, but the site at click here contains a very comprehensive troubleshooter. Just work through it methodically, do not try jumping about from quick fix to quick fix.

  itw2 23:42 17 Jul 03

Yes I have the swich on at the back. I am getting power into the PC because the front LED comes on when I push the start button but apart from a slight momentary noise from the power supply there is nothing else. I had alook at the trouble shooter but it doesn't seem to recognise my problem!

  spruce 23:52 17 Jul 03

Did you get a manual that came with your mobo. If you have it is well worth checking the jumpers are in the correct position, as they are not necessarily set in the default position.

Also the pins where the fan power goes to, check that you have put the connection right home.

Also check that it is the correct pins that you have fitted it to.

There are loads of other potential reasons for having this problem. Read the manual carefully.

  jazzypop 23:52 17 Jul 03

Are you certain that the power button on the case is fully depressing the power switch on the chassis? I had the same problem / symptoms on a friend's PC a while ago - Diesse diagnosed the cure for me :)

  itw2 09:06 18 Jul 03

Thanks for the responses. I believe I have all the connections correct. I am a 'novice' and I was therefore as careful as I could be even marking the wires going to the front panel to mantain the same polarity. I have removed the 'reset' connection and the HDD led connection just in case I got these wrong. I think the button is making because the power LED on the front panel comes on and I can also switch off the LED by keeping the front switch depressed for about 3 seconds. However nothing else works. I will check the CPU fan connection when I get home. I am pretty certain it is in the correct place.
Has anybody any other ideas as to what might be the cause with these symptoms? One last thought. Is it possible that the front power button is connected the wrong way round? I have been reluctant to change the polarity in case I cause a serious problem. Is there any standard wiring colour convention so I can check?

  Bodi 09:28 18 Jul 03

"Is there any standard wiring colour convention so I can check?" - usually, but not always, the darker of the two wires from each of the front connector leads is "+" the lighter of the two "ground". You cannot damage anything by putting them the wrong way round - it just won't work.

Is your floppy drive light coming on? If not, check that the power lead is connected properly and not misaligned. This will cause same problems you are having.


  Bodi 09:36 18 Jul 03

On a more pessimistic note - if the regulator in your old PSU failed, it could have damaged a lot more than the motherboard. I hope not, but is there any way you can get the CPU, Graphics card, memory etc. etc. checked out?

Only mentioning this because when it happened to me, it damaged motherboard, hard drive, Graphics card, SCSI controller card, CDRW drive, CD-ROM drive - etc. etc. - BUT strangely enough, not the CPU.


  itw2 10:01 18 Jul 03

Thanks. No nothing else is coming on. I will check the floppy power.
My local PC shop was supposed to have checked memory and graphics card. I have assumed(perhaps wrongly) that with anything else damaged I would at least get some sign of life if only the single 'BEEP' at start up. Can anyone advise? I can disconnect the CD and CDR and it should at least give me access to the BIOS.

  seedie 10:29 18 Jul 03

You've a new power supply and a new motherbd.

Either one or both could be faulty.

You've got some connections wrong?

Can you get into the BIOS?

Can you boot from a floppy.?

Good luck


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