MacBook Pro 820-3476 random screen fickering

[Francisco.s]

Hi, this MacBook Pro with 820-3476 motherboard presents random flickering.

It does even at boot screen pressing alt key at boot time.

I have tested a good screen, but random flickering is still present.

There are no signs of water damaged.

I have checked all main voltages with a digital scope, but it didn't catch anything.

Any ideas about it?

Thanks.

[Francisco.s]

Re: MacBook Pro 820-3476 random screen fickering

I forgot to mention that image is ok via hdmi.

It starts at the very beginning, and not increase with temperature, and it's the same whith battery or charger. (also only screen and motherboard connected)

[mon2]

Re: MacBook Pro 820-3476 random screen fickering

Sounds like the lcd backlight is flaking out on you?

Check for the backlight rail voltage during these fluctuations. Also see if the enable to the backlight is stable during the same event.

[piernov]

Re: MacBook Pro 820-3476 random screen fickering

We have no idea what you mean by flickering. Post video.

[Francisco.s]

Re: MacBook Pro 820-3476 random screen fickering

Check for the backlight rail voltage during these fluctuations

Hi moon, yes it is a real nightmare.

I have tested the following voltage/signals and found no fluctuations:

EDP_BKLT_PWM

PPVOUT_S0_LCDBKLT

PP5VR3V3_SW_LCD

I have to test more signals on J8300, (edp connector) but it is difficult to test due to the random character of the issue.

[Francisco.s]

Re: MacBook Pro 820-3476 random screen fickering

We have no idea what you mean by flickering. Post video.

I will make a video and post the link.

Sometimes the brightness of the screen fluctuates, and sometimes seems to lose vertical an horizontal sync.

It is difficult to explain, but there are no pixelation or blur.

[Francisco.s]

Re: MacBook Pro 820-3476 random screen fickering

Unfortunately the laptop has been returned to the customer without repair.

I wanted to do some more tests and a video, but customer wants a quick solution.

Anyway thanks a lot for your help.

[ktmmotocross]

Re: MacBook Pro 820-3476 random screen fickering

Unfortunately the laptop has been returned to the customer without repair.

I wanted to do some more tests and a video, but customer wants a quick solution.

Anyway thanks a lot for your help.

did u try to resolder HDMI pins?

[ktmmotocross]

Re: MacBook Pro 820-3476 random screen fickering

did u try to resolder HDMI pins?

forgot about my post

[mon2]

Re: MacBook Pro 820-3476 random screen fickering

The following brief video from Louis may be worth a quick view to see if you have a related case:

https://youtu.be/JGNOGHXhpbQ?t=2659

He chats about screen flickering.

[Francisco.s]

Re: MacBook Pro 820-3476 random screen fickering

He chats about screen flickering.

Hi mon2, this video from Louis is about backlight problem.

Did you copy the correct link or is there an error?

The title of the video I watched is:

820-2915 no backlight, 29v - how are we 29v w/ no brightness & how do we fix it?

i'm always learning from Louis videos, so is not a wasted time.

Thanks for your help.

[mon2]

Re: MacBook Pro 820-3476 random screen fickering

Watch the video from the link that was shared. He discusses other reasons for the flickering.