Ethernet and Wireless LAN only work when laptop is on AC power

I just picked up a used Sony VAIO VPC-EG37FM/W laptop. I was aware that it had some issues, so I got it real cheap with the intent of fixing it up.

As I started working on it, the first thing I noticed is that the BluRay/DVD/CD drive doesn't work at all. It won't even eject when I press the button on the tray. But, as I started working with it, I also started to experience what seemed like very erratic, random issues with the network connectivity. After several reinstallations of Windows 7 and Sony drivers, however, I have identified the pattern. When the laptop is on AC power, connectivity is not a problem. When I'm on battery power, however, the network adapters cease to work and actually completely disappear from Device Manager. The is true even when the battery is fully charged and everything else works normally.

I have already tried going into all the power management settings for the laptop itself and for the network adapters and made sure that they are not being shut down when the laptop is running on battery power, and yet the problem persists.

So my question is... does this sound like something that could be hardware related rather than driver or OS issue? If so, is there any way to test the motherboard or other components to determine what might be the underlying cause?

Any thoughts? Thanks!
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More about ethernet wireless work laptop power
  1. Make sure the power options are set to PERFORMANCE mode, not balanced or power saving....

    You can also check that the wifi card is plugged in nicely and the aerial (antenna) is buttoned onto the card nicely and is clean. it usually is easy to access it without removing the whole mobo...
  2. I already tried the power options to no avail. I can check on the wifi card. It still seems curious that the ethernet adapter has the same problem as the wifi. If one goes out, so does the other.

    Anyway, I'll give it a shot and report back...
  3. It is a strange one. How long does the battery last from full charge? If it is only a very short time (say 30mins) then perhaps it isn't able to push enough current to the network stack...
  4. The battery lasts a couple of hours when fully charged. I should also mention that I took it apart, and all the physical connection to/from the Wifi card seem OK.
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