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User profile for user: Veracity Mendacity
Veracity Mendacity Author
User level: Level 1
4 points

Light Sensor in iMac late 2013

Hi,


My late 2013 iMac has started varying the display brightness even though "Automatically adjust brightness" is deselected. I have tried various suggestions from the forums (e.g. resetting the PRAM and several other things). I've ruled out power connections being loose and I've made sure that I'm using a surge/overload protector.


Now I'm wondering if the ambient light sensor itself is faulty?


  1. What else should I try?
  2. Whereabouts is the sensor located?
  3. Would covering it stabilise the brightness?
  4. I do have a lamp next to the iMac. Would that impact the sensor at all?
  5. And, if all else fails, can it be repaired or replaced?


Many thanks in advance

iMac 21.5″, macOS 10.15

Posted on Jul 18, 2022 5:55 AM

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User profile for user: den.thed
den.thed
User level: Level 10
83,152 points

Posted on Jul 18, 2022 7:09 AM

If it has an ambient light sensor, it is behind the small hole next to the built-in camera.

In addition check your Night Shift settings to make sure they are disabled "Off and Less Warm

If the display brightness is flickering or fluctuating, then it could also be a bad backlight or backlight inverter.


For reference see > Change Display preferences on Mac - Apple Support

and > If your Mac display is slow to reach full brightness - Apple Support

then "Displays" at > Set Accessibility preferences on Mac - Apple Support

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User profile for user: den.thed
den.thed
User level: Level 10
83,152 points

Jul 18, 2022 7:09 AM in response to Veracity Mendacity

If it has an ambient light sensor, it is behind the small hole next to the built-in camera.

In addition check your Night Shift settings to make sure they are disabled "Off and Less Warm

If the display brightness is flickering or fluctuating, then it could also be a bad backlight or backlight inverter.


For reference see > Change Display preferences on Mac - Apple Support

and > If your Mac display is slow to reach full brightness - Apple Support

then "Displays" at > Set Accessibility preferences on Mac - Apple Support

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Light Sensor in iMac late 2013

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