power cuts out in 3 seconds

TimTim Southwest PA Icrontian
edited December 2005 in Hardware
I'm working on a computer that had viruses and a bad BIOS chip in it. The motherboard had NO markings at all, so I wasn't able to reflash the BIOS.

Someone I know "sold" me an Asus MEB-VM Version 1.1 motherboard to replace it. We started it up at his place and it worked fine.

I came home, replaced the CMOS battery, and hooked it up in the computer. When I press the power button, the power supply fans, case fan, and a light on the hard drive will turn on for about 3 seconds and then cut out. The CPU fan doesn't run, the hard drive doesn't spin, and it makes no attempt to boot up or post. Everything appears to be installed correctly, the power connectors on the motherboard were clearly marked, and I didn't change any jumpers.

Only way to make it turn on again at all is to pull the power cord out of the power supply for 10-15 seconds.

Anyone got any ideas?

Comments

  • primesuspectprimesuspect Beepin n' Boopin Detroit, MI Icrontian
    edited November 2005
    sounds like it's overheating and shutting down.
  • GHoosdumGHoosdum Icrontian
    edited November 2005
    What prime said is the most likely answer.

    Also, it could possibly be grounded out to the case.
  • TimTim Southwest PA Icrontian
    edited November 2005
    It worked fine at the other guys house. I brought it home, plugged in the same type of things (433 Celeron cpu, ram, etc), and it screws up on me. Even the CPU fan doesn't turn. I left out the extra stuff, like the sound card and modem to minimize problems.
  • GHoosdumGHoosdum Icrontian
    edited November 2005
    Tim wrote:
    Even the CPU fan doesn't turn.

    That really makes me think that prime is dead on. Check the power to the CPU fan, try a different motherboard header, molex pin, or whatever you're powering it with. If that doesn't help, try a different CPU fan.
  • primesuspectprimesuspect Beepin n' Boopin Detroit, MI Icrontian
    edited November 2005
    Touch the heatsink when you power it on. Does it get really hot, really fast?
  • TimTim Southwest PA Icrontian
    edited November 2005
    I took the motherboard out of the case and set it on a foam rubber packing sheet for insulation. Plugged in the basic things (monitor, keyboard, mouse, hard drive) and now it'll go to the BIOS.

    Now it'll boot up, but it's saying "operating system not found" on 3 seperate hard drives I've tried.

    The CPU heat sink stays cool.
  • TimTim Southwest PA Icrontian
    edited November 2005
    I got it to run successfully on a Knoppix 3.6 bootable CD. At first, Knoppix was telling me that 64 MB of RAM wasn't enough, it needed 82 MB minimum, so I shut it down, put in 512 MB, and now it works fine.

    Next step is to electrically cover / insulate all motherboard contact points in the case and try again.
  • Straight_ManStraight_Man Geeky, in my own way Naples, FL Icrontian
    edited November 2005
    Tim wrote:
    I got it to run successfully on a Knoppix 3.6 bootable CD. At first, Knoppix was telling me that 64 MB of RAM wasn't enough, it needed 82 MB minimum, so I shut it down, put in 512 MB, and now it works fine.

    Next step is to electrically cover / insulate all motherboard contact points in the case and try again.


    Was the same PSU used both times??? How tall are the standoffs??? They do come in various heights, so taller standoffs might be needed and might save the use of lots of liquid electrical tape. Second, those short electrical contacts CAN dissipate a bit of heat, so taller standoffs are better than liquid electrical tape.
  • TimTim Southwest PA Icrontian
    edited November 2005
    I got it working, more or less. The latest trick is for it to partially install Windows XP, then on a reboot (part of the install proceedure), the screen says it can't find a hard drive connected to the computer.

    The same power supply was used for all tries, an Antec 350 watt unit.

    The standoffs are stamped into the sheet metal of the case, and are about 5/16" tall.
  • rc1974rc1974 Grand Junction, CO
    edited December 2005
    Tim wrote:
    I got it working, more or less. The latest trick is for it to partially install Windows XP, then on a reboot (part of the install proceedure), the screen says it can't find a hard drive connected to the computer.


    Hope you have it working by now. :)

    I'd agree that the problem sounds like a short. It sounds as if the PSU's overvoltage protection was kicking in. The result is that you'd need to disconnect the AC power to "reset" the PSU. Anyhow, that 3 seconds may have been enough to damage something. Stuff can get bumped around during transport.

    My dad's computer would had the same sort of problem, but it would only shut off after being touched (static electricity). I went throught 2 PSU's and 2 mainboards (all 4 fried) trying to fix his comp. The culprit ended up being the case. I replaced it, plus the other parts, and he's had no problems for over a year.
  • TimTim Southwest PA Icrontian
    edited December 2005
    The person who sold me that motherboard took it back and traded me for another board, this one is a Micron DR737 with a Slot 1 Pentium 2 400 Mhz processor. This one had better work. He'll be hearing about it if it doesn't.
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