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A1418 / EMC 3068 / iMac 18,1 / 2.3 GHz dual-core i5 processor. Released June 2017.

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Buzzing noise, turns louder when brightness is up

Hi all!

A couple of months ago I upgrades my iMac 2017, 21,5” model with a SSD and RAM.

It worked perfect. I was running BigSur. After the BigSur update from 11.0 to 11.1 I’m hearing a buzzing noise. I first I tought it was the fan, but I dont think so. I installed ‘Macs Fan control’ and turn down the speed. The noise didn’t go away/decrease.

When I decrease the screen brightness to almost 0 then the noise is almost gone.

What could it be?

Thanks!

Update (03/04/2021)

Hi all,

I didn't repair the Mac. All functions were working, noise didn't get louder so I went with it.

After working on the Mac I shut it down and after 45 minutes I want to start working again…The Mac did not start up. Nothing, no noise, connection, screen. Also disconnected power cord.

What to do? Replacement of PSU?

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2 Commenti:

Can you determine which area in the machine the buzzing noise is coming from?

da

Bottom left corner I think

da

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2 Risposte

It sounds like a power supply issue or

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5 Commenti:

Logicboard replacement

da

Yes, it think so. You wrote "Or"....;) ?

da

@consistent logicboard? Never heard of that. What is that for?

da

Rob logicboard on 2015 15 inch MacBook pro can have that problem. Bottom left is a power supply

da

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What you are hearing is a coil hum/whine. Your system has transformers and inductor coils which can become loose in their cases so they vibrate.

It has nothing to do with the macOS release your system has on it.

You’ll need to open the system up and carefully try to narrow down where the sound is coming from so you can isolate out the part that will need either replacement or repair.

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Okay...but what part controls the brightness of the screen? When I turn up the brightness the noise gets louder.

da

There are two parts the power supply as well as the logic board. Opening the system and listening is really the only way to isolate out which.

da

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Rob Smeets sarà eternamente grato.
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