Main board power supply

  Paroxetine 20:36 26 Jan 2003

hi all, a real technical question today.

I have the following set up.

KT4 board, Duron 1Gz, 512mb, 40gb drive, CDROM, CDRW, usual extras such as modem, NIC, SCSI controller for the CDRW, sound card and graphics.
and a 300w PSU.

The PC was working fine, no downloads occured, no programs installed I was in fact rather impressed by how stable and great things were going. I turned the pc on and I heard the fans come to life, and left the room, then upon returning the PC is dead. Examine the main board and nothing is found, the PSU smells burnt so I changed the fuse out. The fuse blew out again, this time though on inspection a diode on the board was also burnt out. Upon intsalling a higher rating PSU 350w this time, the mobo fails to boot (there is no action when the on off swtich is pressed), the PSU is out-putting a smaller then I would like voltage (10.5) though not sure that this is being measured properly. The +12v +5v continuty when using a voltmeter continuity test beep for 2 secs then stop and 'reset'.

In a nut shell....

How do i measure the voltage on the PSU to confirm that its all working as it should be.

If the main board is at fault, what can I look for on the boad as obvious signs?

Hope any one can help me with this, tis beginning to drive me a little mad. :D

Thanks for your time.

  DieSse 20:42 26 Jan 2003

It's quite possible that a PSU fault can do lots of consequential damage. I've had them that have done no other damage at all, but just the other day had a PSU fault that blew - Motherboard - HDD - CD-ROM - Graphics Card - Modem - RAM (but not CPU or Floppy).

In the above disaster, the blown chips were quite in evidence when visually inspected.

So basically I'm saying anything might have gone.

  woodchip 20:53 26 Jan 2003

When you smell burning you never put a new fuse in, I would say your comp as add it, you could start with a new motherboard first to check if other things will or not work. As you have already replaced the PSU

  Paroxetine 13:14 27 Jan 2003

thanks for the postings. The new PSU works fine, its the motherboard that was at fault. There was a cmos chip that is showing signs of heat stress and nothing else, so I am taking photos and sending them to the maker to see what they can do if anything. I would think that the PSU wouldnt have caused the fault and that the board suffered a failure, increasing the load on the PSU and blowing the fuse. When the replacement happened it did it again this time taking the PSU further into the bin.

Many thanks, P.

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