Solved Why Does The Screen Brightness Reduce Once The Screen Turns On Imac Intel 20 Emc 2133 And 2210

Chosen Solution

Whenever the screen turns on, be it when booting up or when waking up from sleep, the screen brightness comes on as per the set brightness levels and just after a second, the brightness drops by about 20% and stays like that. If I put the system to sleep and again wake it up the same thing happens - the brightness comes on as per the display settings for a second and then the brightness drops by about 20% and stays like that. This iMac does not have an ambient light sensor so what could be causing this issue?

Your displays CCFL lamps and/or the inverter are breaking down ;-{ The CCFL are just not available any more, besides they are very tricky to get to iMac Intel 20" EMC 2133 and 2210 LCD Backlights (CCFL) Replacement You really need to just replace the full display assembly with a recycled part 20” iMac LCD panel, Apple P/N 661-4671 - AUO # M201EW02 and here’s the guide iMac Intel 20" EMC 2133 and 2210 Display Panel Replacement Here’s the info on the inverter 20” iMac Inverter Board, Apple P/N 922-8204 and its guide iMac Intel 20" EMC 2133 and 2210 Inverter Replacement