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w00t951

macrumors 68000
Original poster
Jan 6, 2009
1,834
53
Pittsburgh, PA
I just noticed that my Mac makes a buzzing noise due to EMI from PWM. Does anyone know how to fix this?

Running the keyboard backlight at anything other than off/maximum triggers this buzzing.
 

justperry

macrumors G5
Aug 10, 2007
12,376
9,534
I'm a rolling stone.
The keyboard backlight needs little current for it to work, if you get the noise when the backlight is on something is amiss, reason is that the buzzing normally appears only when lots of current is needed.
For instance, if you have a 100% load on the CPU, not for a small current from the keyboard backlight.
 

w00t951

macrumors 68000
Original poster
Jan 6, 2009
1,834
53
Pittsburgh, PA
The keyboard backlight needs little current for it to work, if you get the noise when the backlight is on something is amiss, reason is that the buzzing normally appears only when lots of current is needed.
For instance, if you have a 100% load on the CPU, not for a small current from the keyboard backlight.

No, I've pinned it on PWM used to control the keyboard brightness. I'm at idle, and buzzing is only audible when the keyboard brightness needs to be something other than 0% or 100%.

My question is, is there a way to stop this buzzing? It's slowly driving me insane.
 

justperry

macrumors G5
Aug 10, 2007
12,376
9,534
I'm a rolling stone.
No, I've pinned it on PWM used to control the keyboard brightness. I'm at idle, and buzzing is only audible when the keyboard brightness needs to be something other than 0% or 100%.

My question is, is there a way to stop this buzzing? It's slowly driving me insane.

Only way is to service it, that is if it's still inside warranty.
 
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