Screen flickering on high brightness?

i already made several posts about this mac, i hope this is the final one.

recently i mentioned that my mac has some screen flickering problems, the strange thing is that, its doesnt appear at first, after reinstalling macos it works just fine, untill i bring it out somewhere where its cold, (like taking it to school)

low temperature IS DOING SOMETHING, IDK WHAT and screen starts to flashing, after this cold temperature sessions its starts to keep flashing sometimes, i couldnt understand why and when it starts to flashing, it was just stopping doing it sometimes, UNTILL

today i mentioned that its just stops flashing on mid brightness, setting brightness to medium (or lower) fully stops the flashing screen

im wonder what kind of hardware issue is this?

btw some details: screen has damaged bottom black plastic pannel, also several burned out pixels, beside that it works just fine idk

the motherboard was changed recently, original one had burned out GPU and it was permanently set to the integraded graphics, (also it had modified bios chip, idk i mentioned it cuz it may be usefull for you) this new motherboard is working just fine, every detail is on its place and it isnt missing anything,

ALSO its worth to mention that, while still on old motherboard with damaged GPU, failed GPU's one of the symptoms were that, backlight was working on full strenght, it wasnt possible to do something about it (i couldnt change the brightness), and the failing GPU also was resulting the same screen flickering, but the flikering was dissaperaing after turrning off the automatic graphics switching

and the last thing, power jack is damaged (it has overheating marks) im planning to change it, charger itself overheats, and the battery life is at 80% could it be related to this problem?

so what u think? im guessing that maybe old motherboard with burned GPU and backlight stuck at full bright may be damaged something there and now its kinda failing? also the mac works great in other aspects, it perfectly runs the games that are comparable with its hardware (i got no problems with its specs, i just need this mac for studing, youtube, internet and some games)

so yeah thats all, point of this post is that to me to understand what may cause this situation

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4 comentarios:

the flickering dissapears on full bright after time bruh, it may be temperature sensitive failing component as ive been told

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@rikkopaw "setting brightness to medium (or lower) fully stops the flashing screen" us usually a backlight issue. The brighter you have the backlight the more power the backlight needs. Could be an issue with your backlight driver on your logic board or your backlight inside the display panel.

I would measure the backlight voltages. Normal would be around 25V to 40V (backlight 100%) and if you have more than +45V then there is no load on the backlight circuit., basically your screens backlight are not working. Since yours "flickers" I would expect it to go from 25/40V then above 45V and then a varying voltage as teh screen flickers. Sounds to me like a bad screen but see what voltages you get.

If it goes way below the 25/40V then the issue could be the boost circuit on your logic board.

You can measure the voltage on pin 1 on your display connector. Step 29 on this guide MacBook Pro 15" Retina Display Mid 2012 Logic Board Replacement shows teh connector. Pin 1 is the one to the far right.

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@oldturkey03 not the backlight is flashing, its the LCD, colours are changing slightly, its moving from bottom right corner to upwards

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@rikkopaw - This gets into a mis-scan of the panel which is what your older question was on. The shimmering of a given area of a static image and it slides around is the symptoms of the T-CON failing which is part of the display assembly. Someone with good micro soldering skills most be able to fix the T-CON, for most its time to replace the display assembly as that is the easier fix.

You'll need to live with it other wise lowering the brightness will make it less noticeable, not letting your system get so cold also helps.

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