KC Micro Tronix
Member
This machine came in for no backlight. I did not find any water damage and the fuse was good. So I replaced the driver IC U7701 and that fixed the problem "almost" The machine isn't quite right. Along the bottom left of the screen you can tell that some of the back light LEDs are not properly functioning and this makes that side a little darker. See the picture.
I have encountered this before and ended up replacing the driver ic to fix it so I tried another one just incase and it did not solve the problem.
I checked R7717-R7722 and they were all good. I also checked all the resistors around U7701 as well as replaced it a second time. This issue shows up on both the original screen and my test screen so it is definitely the LB.
R7721 and R7722 (BKL ISEN5 & BLK ISEN6) are both reading 4-8v which is not right. There is not muchere except for the plug and U770. I really don't have a solid understanding on exactly how this circuit works. I have looked at J8300 very closely under the microscope and can't find anything wrong with it.
I have encountered this before and ended up replacing the driver ic to fix it so I tried another one just incase and it did not solve the problem.
I checked R7717-R7722 and they were all good. I also checked all the resistors around U7701 as well as replaced it a second time. This issue shows up on both the original screen and my test screen so it is definitely the LB.
R7721 and R7722 (BKL ISEN5 & BLK ISEN6) are both reading 4-8v which is not right. There is not muchere except for the plug and U770. I really don't have a solid understanding on exactly how this circuit works. I have looked at J8300 very closely under the microscope and can't find anything wrong with it.
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