G750JW-DB71: No display upon wake. Cannot get it back even after CMOS dump

Hello All,

New to the forum. I purchased this machine last summer, and it was my first ASUS laptop. I've enjoyed it thoroughly!

Since purchased, I've added a SSD as primary boot drive and swapped the DVD for a BluRay drive. Otherwise, it is stock configuration. I've updated the BIOS to the most recent for this machine.

I first encountered this issue when I tried to wake the machine from sleep. The keyboard lit up, the drives (conventional HD and Bluray) spun up, but I had NO display - nothing, not even the backlight. I did a HARD shut down by holding down the power key. When I restarted the machine, same thing - no POST or Windows 8.1 boot screen. I had a hunch that it was display/CMOS related, but I wasn't sure how to reset the CMOS, so I hooked up a VGA monitor and re-started the machine. Voila! I now had an active LCD AND external monitor. I shut the machine down using Windows and disconnected the external monitor. Restarted and everything was back to normal. I made a note to self - don't sleep the machine until I figure out why this happened.

About a week later, I did it again. this time I got on chat with ASUS tech support and they told me about the CMOS reset trick with power button and all power removed. That worked! So - I figured now that whatever the problem was, it was cleared away...right?

Wrong.

Left for vacation a few days ago, and forgot to do full shut down before going to bed. Wouldn't come up the next morning. CMOS dump didn't work either. ASUS Chat support couldn't get me any further than the last time... I guess that was their one golden bullet. The only trick I have left is to hook it up to an external monitor again and see if that get's my display back.

I've studied the various guides on dis-assembly (here and youtube), so I'm comfortable taking the machine apart... but before I do, I was hoping to have some ideas on what to try and/or look for. The nature of the symptoms doesn't suggest a bad/intermittent display harness since I NEVER saw any flickering or drop out or similar while using/moving the machine. The one thing I come to is perhaps it's the switch that senses the lid open/closed..?? I'm guessing that switch is accessible, but it's not obvious from the videos I've seen. I was wondering if anyone here has had similar issues with the G750 series, and any suggestions would be appreciated.

Thanks!

Regards,
Gary (Dox_in_Calvert)

 

Well obviously check the display cable, it wont be a proper short as the machine would not power up. Re-seat the GPU if it comes to that and do manual cmos reset by removing the cmos battery and reconnecting it.

 

@Meaker: Thanks! I was going to check all of those - including CMOS battery removal.

.. One other thing I uncovered was a similar problem with the G53 series and the magnetic sensor used to detect the lid closing...they would go defective and people couldn't start their machines. Mine will start, but the display is completely 'off'...leading me to think that the machine is powering up in a lid-closed mode to be used with external monitor...?? Many business laptops work in that mode if they are seated in a docking station (I've got one at work).

Does anyone know where that sensor is located on the G750 series? Is it part of the trackpad assembly?