Dimension 8400 Power Button

Penz2k7

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

Bev.




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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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Sure the battery on the motherboard is good?

Ron

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

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, <ADMIN NOTE: Broken link has been removed from this post by Dell>

here, it's for an Optiplex GX50 Small Mini Tower, but the procedures are the same.

Bev.






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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

Message Edited by Penz2k7 on 05-04-2007 09:46 AM

Message Edited by chucon on 05-14-2007 09:09 AM