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A1534 2017 flickering during boot up by pressing a key

Dozer

Dozer

Member
this machine cam in with broken display and problems during using keyboard. no signs for liquid spill.
I replaced the display and the topcase. working fine but client send back now because its flickering during boot up in to the user account pressing a key.

i thought a cable or topcase problem. but now i tryed via usb an external keyboard and pluged off the trackpadflex cable 821-1935 and the same effect. the effect is also with starting from external harddrive

no idea what can i do here, need some help please.

a video from flicker is here: https://www.lrzt.de/flicker.m4v

in the video i press often a key, after seen the desktop i can press the keys without the flicker effect. And during selsct the user account and entering pw there is no flicker
 
Dozer

Dozer

Member
I just still replaced the display with a known good working one and the flex cable and the trackpad and the topcase but same problem
here is still a second video with the problem from my client. he had the problem as well during the acount was activ
www.lrzt.de/flicker2.mov
 
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Dozer

Dozer

Member
yes PRAM reset i tryed, how to start SMC bypass mode?
i just noticed that all screens I tryed was 2015, the mainboard is an 2017 is this a problem?
 
2informaticos

2informaticos

Administrator
Staff member
Read "How to collection" thread, for some usefull tips.

The first screen replaced was working for a while; was 2017 model too?
 
D

dukefawks

Administrator
Is the audio working? If the system finds no audio device and it wants to give audio feedback from some keyboard entry it will blink the screen.

Also you cannot put a 2015 LCD on a 2017 machine as the 2015 LCDs only have a "sleep magnet" on one side so the machine will never sleep.
 
Dozer

Dozer

Member
ok, at first now i replaced the display with a 2017 one because of the sleep magnets, thanks @dukefawks

and. the audio is not working, dont show any audio device.
under the thermal cam, if the audio board is connected the flex cable getting very quick very hot starting on the mainboard connector. tryed already another good cable and another audio-board.

the connecor on the mainboard looks clean
 
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