October 29th, 2013, 06:39 PM
Interesting MB fault
I have a PC which has been connected up to the mains for many many months, maybe nearly 2 years.
I just use the front 'power' switch to wake it.
The other day I disconnected it from the mains for a day or two.
Now it fails to POST.
I have checked all the psu voltages, reset the CMOS, replaced the backup battery (which was flat), re-seated the ram and processor.
No beeps, nothing.
The cpu fan comes on and the hard drives spin up, but no other sign of life. No video signal at all.
Any other ideas what I might try?
It's quite an old machine with an Asus A7N8X MB
October 29th, 2013, 07:31 PM
according to the images I found of your MB, there should be 8 electrolytic (canister) capacitors between the Processor and the AGP video card slot.....look at the tops of those capacitors [silver tops] and look for any bulging or signs of leakage .
If you see either, then, that is your problem.
If you are comfortable using a soldering iron, you can find replacement capacitor kits on ebay and other places..and replace the bad capacitors.
October 30th, 2013, 05:40 AM
Most of the caps look fine, but I did find two near the psu connector, part of some sort of switchmode psu judging by the other components in that corner of the MB.
Both look slightly bulged and one might have a tiny amount of brown stuff leaking from the top.
I will get them out and replace and see what happens.
Thanks for your help!
October 31st, 2013, 01:55 PM
Replaced the caps, still no luck.
Tried a different psu today, no change, but while plugging stuff in and out 'breadboard' style, I found the reset switch was causing the MB not to boot.
I checked the reset switch and it meters open and closes when pressed. No shorts to chassis either so god knows what's going on there....
Just got to get the RAID going again now.
thanks for your help.
October 31st, 2013, 02:09 PM
RESET switch is supposed to be a normally open momentary switch and only "close" when pressed .
POWER switch is usually an actual OFF/ON.
But, glad you got it figured out..and , it didn't hurt anything to replace those capacitors..may even extend the MB's life a little longer for ya.