BleepingComputer.com: Strange Laptop Motherboard Problems

Hi everyone. I have only just signed up but have used your site for reference many times. I thank you all for your help in the past but now I have a problem that I can find no answer to.
I have a laptop that wont wont turn on unless the mobo battery is removed! Take it out and it will power up just fine. Put it in and it charges the battery but will not turn on.
I havn't tested the battery yet to see if it works as I havn't got around to it but would this make a difference?
Just for the record it's an emachine jobbie about 2 years old with widescreen.
Any ideas on this?
Thanks in advance.
Phill.

Quote

I have heard of this being caused by a bad battery, I would definitely check it with a voltmeter.

DaChew, on Jul 20 2007, 07:40 PM, said:

Thanks Chewy, I had heard this somewhere in the past and dissmissed it as daft but looks like it could be so. I will post when I have tried it. I forgot to mention that it had previously had water damage and the keyboard was replaced by emachines when it was under warrenty. Maybe the water killed the battery? But then if it had got that far I'd expect it to have fried the mobo too. Anyway I'll update soon.

This depends on how the AC adapter is wired within the computer. Typically an AC adapter can power the computer and charge the battery, so if there's an issue with the circuit that includes the battery, then you'll get this behavior when the battery is installed. Removing the battery may remove the path of the fault, so then the system works.

The fault will likely lie with the battery or with the motherboard. You can test the battery, but if there's a fault, it could also leave the battery uncharged - so that's not a definitive diagnosis. I'd suggest trying another battery simply because that's easier and cheaper than fixing the motherboard.

Ok the old battery was flat so I installed the new one and all worked fine. I then thought that it could do with a fresh install as the OS was slow. I rebooted from XP CD and formatted the hard drive. It then went on to install windows and just froze. Now it turns on but won't display anything on the screen or on a monitor. It will spin the CD and hard drive but thats it. I guess this is the video now? Tried removing the onboard battery again but nothing this time. I guess the motherboard is shagged out! Oh well.

Many years ago I bought my very first TV and left a Coke can on top of it. Moisture from the condensation on the can dripped onto a circuit board and the TV stopped working.

Dad opened up the case and found that the water had "carbonized" the circuit board. He used a pocket knife to scrape away the "carbonization" and fixed it.

But that was in the old days of single layer PCB's - I don't think that this will work on a more recent, multilayer PCB.

Is the new battery charging? back to the voltmeter?

DaChew, on Jul 21 2007, 02:44 PM, said:

Yeah it's not a problem with the normal battery but the bios battery. It's working again now! It seems time helps it! I noticed there was no heatsink on the video chip and the one I saw second hand on Ebay had one. I have stuck one on it with some thermal paste. It is now installing windows. Let's see how it goes.

Well it installed but it's still playing up sometimes. I'm using it now actually. I lifted it up earlier to check the model number for the drivers and when I put it down the screen went bizzare with random graphics and froze. Funny thing is it rebooted and when I bashed it around it didn't happen again. I have left it on now for 3 hours and it's still working. It's doing my head in!

Ahhh, the wonders of "percussive maintenance" !

Around my neck of the woods its called a " technicians tap"