Dimension 8400 Power Button

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Dimension 8400 Power Button

  • We have a Dimension 8400 at my office that stopped working a month ago.  The ONLY way to power it up (using the power button) is to open the case and remove the battery (I know, makes no sense to me either)  Have replaced the power supply and get the same result.  Today we replaced the motherboard and still have the same result.  My question is, do these power buttons actually go bad?  Or is there some setting somewhere that turns this off and somehow removing the motherboard's battery resets it for the next time you power it on.  Once on it works fine, but if you shut it down you are forced to remove the battery again.


    Message Edited by Penz2k7 on 05-02-2007 01:16 PM
  • Penz2k7

    Have you tried replacing the front control panel and ribbon cable?

    These are proprietary items and if you are not under warranty, they can be obtained from Dell Spare Parts.

    Bev.





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  • That was going to be our next step, but after replacing a power supply and a motherboard I wanted to see if anyone out there had any other thoughts on this problem.  Thanks for your response.
  • Penz2k7

    Check out the ribbon cable from the motherboard to the front panel first.

    Bev.




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  • Sure the battery on the motherboard is good?

    Ron

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    Ron

    Forum Member since 2004

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  • Yeah.  We have replaced the battery in the "original" motherboard, and I can only assume the new motherboard actually came with a new battery.  Correct me if I'm wrong though, isn't the battery on the motherboard "mostly" used for maintaining the time and date?  Either way though, I can't see how the battery would cause the issue I have, nor do I understand how that "resets" the system and allows me to only boot up once.
  • Battery on motherboard powers NVRAM which holds the info about installed hardware, eg type/size of hard drive, amount of RAM, etc, in addition to keeping the clock/calendar running.

    So when you remove the battery, you reset all BIOS settings to factory defaults which apparently allows the system to boot properly. If you have a battery you know is good, put it into the new motherboard. It's reasonable to assume the new board came with a good battery, but one never knows.

    I suppose it's also possible you have a short circuit in the power switch which is draining the battery when the system is off just enough to scramble the NVRAM settings.

    Do as Bev suggested and check the wiring to the button and maybe see if you can buy a replacement.

    Ron

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    Ron

    Forum Member since 2004

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  • We did replace the battery with a brand new one.  And today I ordered a new power button assembly.  Thanks for the responses.  Hopefully this will fix the issue.
     
    By the way, is it easy to get to that power button?  We were looking into it the other day and it looked like a pain to begin with.  Not a "tool less" job like changing anything else.
  • Penz2k7

    Oh, it's a pain alright.

    The power button and circuit board is one unit. Dell has not published a guide to remove the front panel and control panel of the Dimension 8400, but you can use the guide, here, it's for an Optiplex GX50 Small Mini Tower, but the procedures are the same.

    Bev.






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  • OK, I'm back.  So just a quick run down of what has been done to this pc.  We have replaced the power supply, motherboard, power button (and cable) and tried 3 different batteries on the motherboard.  We are still not able to restart this machine after it is shutdown.  The only way to restart is to remove the battery.  I have run out of possible causes here.  So I guess my question is, is there any chance this could be a software problem or a BIOS problem?  I've replaced all except for hard drive and cd rom.  By the way, we tested the usb ports in front to make sure it wasn't the cable that connected those ports to the motherboard and that worked fine as well.  Thanks in advance for your thoughts.
     
     
    Edit: Reason I ask about it being software related is due to the fact that during my research I saw something about it being possible to "turn off" the power button on Dell Servers, not sure if on a workstation.


    Message Edited by Penz2k7 on 05-02-2007 01:19 PM
  • There is an XP setting that tells the system what to do in response to pressing the power button (eg, power off, nothing, etc), but I can't see how that would prevent the system from starting because XP hasn't loaded yet.

    Run BIOS setup and look through the power management settings to see if any are of use. Look at those that say what to do in response to power failure. Suppose you set it to reboot after power failure, and then use a power strip or surge protector to turn off power to PC after shutting Windows down normally. When you hit switch on the strip/surge, it should boot without pressing power button. Doesn't solve the problem but gets around it, if it works...

    Also try stripping down to just bare basics. Disconnect data cables from floppy drive, optical drive(s), remove all PCI cards, except video card (PCI-e video on 8400), remove all RAM modules, except the one in slot 1, disconnect all peripherals except mouse, monitor, keyboard. Clear NVRAM by removing battery. Reinsert and press power button. Then shut down normally and try booting again just by pressing power button. If that doesn't work, swap every RAM module into slot 1, one at a time. If it works with 1 RAM module, try 2 and then add back other hardware piece by piece until you find the offender.

    Ron

    Message Edited by RoHe on 05-02-2007 12:42 PM

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    Ron

    Forum Member since 2004

    I am NOT a Dell employee

  • OK, I have now removed all cables, and 1 RAM chip at a time.  And still am left with the same problem.  The only option I have left is to check the usb 2.0 cable that goes from the motherboard to the smaller card near the front usb ports which then goes up to the power button via another smaller cable.  Oddly enough we are just about to the point of piecing together a new computer.  Once again, thanks for the input.
     
    edit: In case I haven't mentioned it before, the usb ports do work in front.  So not exactly sure how this cable operates and if only a portion of the cable could actually be bad or not.


    Message Edited by Penz2k7 on 05-04-2007 09:46 AM
  • I suggest that you check the REV of the power Supply that you reinstalled. If the Rev is A00 you need to repace it witha higher revision.


    Message Edited by chucon on 05-14-2007 09:09 AM
  • Oddly enough the new one is REV 01, and the original is REV 02.  I suppose later on I will try to reinstall the original power supply.  Thanks for the tip.
  • Penz2K7
     
    I apoligize for my last, my problem related to a Rev A00 being installed and repeatedly Rev A00 be shipped to me as I needed to replace the A00 with a higher revision. Finally recieved a Rev A01 and the unit is now performing normally!  Again sorry my error last evening!