Chosen Solution
I recently noticed that the screen brightness on my iMac 27” 2017 model not changing, in precise, from the darkest to 30% brightness bar, it can change, but after that, it just keep the same brightness even though the brightness bar can be increased. When I do reboot, and before screen turns bright, I can see some white spots light up from bottom edge of screen, which looks different from what shows on the top edge. Running Apple self hardware test, it didn’t report any issue. So, what could be wrong, screen backlight, inverter, etc.? Thanks in advance! Shaun
The newer iMac’s use a Buck driver which does allow a finer level of brightness. I’m suspecting the control logic is having issues with it’s stepping. You also talk about white spots of light that is either light leakage or your display has an issue. Has someone opened your system? Have you has it serviced at some point? Given its such a new system you likely still have warranty coverage. I would take it to an Apple Store or authorized service center to have it looked at.
Hi, It seems to be a backlight issue based on my experience with iMac’s. I know @danj know a lot about iMacs.
