I have a 2015 MacBook Pro A1398 with no display. The board number should be 820-00426. It does post, has a chime, and keyboard backlight comes on, so CPU does have power. Attached external display and it works fine.
There is no backlight and no display on LCD. I can shine a spotlight through back of screen with SSD removed, and no flashing folder appears.
Prelim tests showed two burnt resistors, R8351 (LCD_FSS) and R7701 (PP_BUS_LCDBKLT_PWR, LCDBKLT_EN_L). Checked for shorts to ground on LCD panel and LVDS cable, none found. Suspect internal intermittent short in LVDS cable, as it appeared frayed through hinge. Replaced LVDS cable and two burnt resistors. Still no display.
At Q7706, I have 11.8v at Source (Pin 4) and 11.7v at Gate (Pin 3), so no voltage at Drain (Pin 1,2,5,6). BKLT_SD is not going to ground at U7701.
After running trace tests for continuity and going through the LCD_5V_EN_L circuit, I came to Q8300. It is a DMB53D0UV NMOS with NPN transistor. When I check it in Diode Mode, I get 0.429 when going Source (+) to Drain (-). Reversing it gives me 0.900 when going Drain (+) to Source (-). This immediately threw a red flag up in my brain. It tells me the transistor is toast. Now this component is in circuit and not removed. I did charge the Gate and test, no change. I did discharge the transistor, no change. Am I interpreting this correctly? Thanks
There is no backlight and no display on LCD. I can shine a spotlight through back of screen with SSD removed, and no flashing folder appears.
Prelim tests showed two burnt resistors, R8351 (LCD_FSS) and R7701 (PP_BUS_LCDBKLT_PWR, LCDBKLT_EN_L). Checked for shorts to ground on LCD panel and LVDS cable, none found. Suspect internal intermittent short in LVDS cable, as it appeared frayed through hinge. Replaced LVDS cable and two burnt resistors. Still no display.
At Q7706, I have 11.8v at Source (Pin 4) and 11.7v at Gate (Pin 3), so no voltage at Drain (Pin 1,2,5,6). BKLT_SD is not going to ground at U7701.
After running trace tests for continuity and going through the LCD_5V_EN_L circuit, I came to Q8300. It is a DMB53D0UV NMOS with NPN transistor. When I check it in Diode Mode, I get 0.429 when going Source (+) to Drain (-). Reversing it gives me 0.900 when going Drain (+) to Source (-). This immediately threw a red flag up in my brain. It tells me the transistor is toast. Now this component is in circuit and not removed. I did charge the Gate and test, no change. I did discharge the transistor, no change. Am I interpreting this correctly? Thanks
Comment