820-2828 Display issue

tlough75

Member
Got an 820-2828 with an external display issue. My customer replaced the GPU but couldn't get it to work. I got it and took it apart and reassembled it carefully and it started to work. I gave it back to the customer and they gave it back to their customer. It has been returned for not working. So far I can get an external image via TB but if I turn on with screen it will light up for a few seconds then goes black. The fourth diagnostic LED also turns off. Once it turn off I cannot get it to repeat the fault unless I leave it unplugged for a while. I assume since I get an image externally, the GPU is ok. Any ideas on what to check next? I think I tried to replace the LED driver board before but it didn't change anything.
 

tlough75

Member
So I put a new inverter board in and it seems to be working, though every once in a while the screen will go black for half a second then come back on. Trying to get password to check temps with HW Monitor
 

tlough75

Member
VIDEO_ON_L goes from 3.3v to .08v as LCD and 4th LED turns on turns on, then after 10 seconds screen goes off and it goes back high
 

2informaticos

Administrator
Staff member
VIDEO_ON comes from LCD panel.
DP_INTRNL_HPD goes off too?
You should try another display and flex.

Be sure R9050/51/10 have 0 ohm.
 

tlough75

Member
Didn't see your last post until now. I replaced the LB and still same issue. This narrows it down to three things that have not been replaced by me. The GPU , The Power supply and the actual wiring harness from the power supply to the rest of the computer. I do have the IR sensor unplugged. Would that affect anything?
 
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