Chosen Solution
Hi I’m sure this has been asked before. I replaced the battery in my friend’s MacBook yesterday without a hitch and the display was fine. My friend contacted me last night to tell me the display brightness is off, it’s darker on the left side and normal brightness on the right. I tried zapping the PRAM, resetting the SMC and even ran the AHT (Apple hardware test). The AHT said no issues. I took a photo of the display and its attached. It might look like it’s completely black in the photo but in real life, it’s just darker.
Is the display going bad, (inverter cable or LCD cable), a graphics card issue? If it’s the display I could replace the display entirely or cables myself. My guess is it’s the display, inverter or LCD cable perhaps. If you need more information, let me know. MacBook 6,1, unibody, late 2009, OS X Yosemite, 10.10.5. 8GB of RAM.
Make sure the LCD cable is plugged in properly, into the board and screen. Most of the time this happens due to the cable not being fully pushed into the logic board, so it is only lighting a number of LEDs for the screen. You can try brushing the inside of the LCD connector with a soft brush and 95%+ isopropyl, in case there is dirt inside, stopping a proper connection. It can be caused by other things (LCD, LED return resistors, etc) but I would say the above is the most likely reason, if it was fine when you had it. The cable probably wasn’t secured properly and came slightly loose.
Check to make sure that the backlight cable is plugged in all the way and free of dust. Make sure the connector is seated correctly and locked in place. It could also be that your backlight inverter is going bad and will need to be replaced.
