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Hi frnds Got a MacBook pro a1278 I’m getting very feable /dull display on the screen Actually it’s intermittent once in a while it gives bright display , wanted to access to displsy cable tried opening from screen end damged front glass however I’ll replace it once I’m.able to fix this issue I got 3.3v on screen fuse, 12.5 on pin3-4 LED BKLIGHT CONNECTOR of screen(b133ee7 v2) I’m not able to figure out pwm enable & brightness control signal(unlike regular led screens) pins from motherboard or screen.end Any help would be greatly appreciated Rgds Veekay
hi sry frnds before anybody was interested in answering my question and help me fix i figured it out the problem, i suppose nobody wanted to share the trade secret haha however i learnt it hard way and indeed costed me cost to the front glass which i tried to remove n broke as i wanted to chk whether cable and screen were ok coming to solution i found out that IC location u9701 which is LP8550 is a led driver unlike our regular PC screen where backlight works using 19v / backlight enable & backlight PWM for brightness this particular mac uses +Ve / backlight PWM sync and 6 Return signals for backlight and brightness which is driven by LP8550 connected via serial resistors i did a flux and reheat of the IC now works perfectly hope this feedback helps somebody someday great day VeeKay
