820-4924 No PM_SLP_S4_L

[Gmorb]

pp3v3/5v_s5 = present
PPBUS S5 HS COMPUTING = present
PPBUS S5 HS OTHER5V/3V3 = present
PPDCIN_G3H_ISOL = present
PPDCIN_G3H = present
PP3V42 G3H - present
PPVRTC G3H = present
PPBUS_S4_X239 = not present
PP5V/3V3_S4 = not present - no pulsing
no PM_SLP_S4_L - no pulsing
no PM_SLP_S5_L - no pulsing
no ALL_SYS_PWRGD


every power rail before S4 are present

 

[2informaticos]

PPBUS present, but what value?
PPVRTC present, but what about PCH's RTC signals?
Any CLK32K signal present?
Do you get magsafe light?
Are you using original Apple charger, 85W?
Post SMC_ADAPTER_EN, PM_BATLOW_L, PM_SLP_SUS_L.

 

[dukefawks]

Exact values? History?....

 

[Gmorb]

I get a magsafe light and using original 85W apple charger. History of the board was water damaged but cleaned by someone else. i did notice some damaged components around and including R1410 area and have replaced and reattached traces.

PPBUS_G3H - 12.60V

PPBUS_S5_HS_COMPUTING - 12.60V

PPBUS_S5_HS_OTHER5V - 12.60V

PPBUS_S5_HS_OTHER5V - 12.60V

PPBUS_S4_X239 - 0V (NO PULSING)

PPVIN_S4_TPAD - 0V (NO PULSING_)

PPDCIN_G3H_ISOL - 16.85V

PPDCIN_G3H - 16.85V

PP3V42_G3H - 3.42V

PPVRTC_G3H -3.3V

PP5V_S5 - 5V

PP3V3_S5 - 3.3V

PP5V_S4 - 0V (NO PULSING)

PP3V3_S4 - 0.008V

SMC_CLK32K - 1.7V

PCH_CLK32K_RTCX1 - 0.42V

PM_CLK32K_SUSCLK_R - 1.7V

SMC_ADAPTER_EN - 3.3V

PM_BATLOW_L - 0.36V

PM_SLP_SUS_L - 3.3V

PM_PWRBTN_L - 3.4V

 

[2informaticos]

"PM_BATLOW_L - 0.36V"
This is bad, should be high; and is related with R1410!

Are you surelly using 85W original charger?
Connect battery too and try to see if starts.

 

[Gmorb]

yes its an original apple branded bought from store 85w charger. it doesnt turn on with battery connected. pm_batlow_l get to 3.3v with it connected.

update: ok so it does infact turn on volume setting werre low and backlight is out i do see a folder when flashing a light to it. so theres that ill try and restore backlight and see how it goes.

 

[Gmorb]

ok so this backlight has been kicking my ass all day. im not getting 12v past q7700 ive checked traces even resistor values are ok. one thing i noticed is when i connect the display i get around 11.9v instead of a 12.9 when i disconnect the display i get 12.8 volts or so. so could it be a bad cable or screen?

i tried swapping led driver but nothing has changed. also on the ppvout_s0_lcdbklt i get a 200mohm resistance to ground. it goes down to about 6mohm reaches kohms then resets and rises again. im still rather new at knowing at what ohms it means theres a short to ground without having the multimeter beep. if anyone can shed some light at how to know if something is shorted by reading ohms i figured ohms and mohms would mean theres a short not sure if im right cause there is no obvious sign anything is damaged either.

on the EDP connector side i can see the test points have been corroded before but cleaned they are slightly discolored.

 

[2informaticos]

BKLT_EN_R is present?
Does the o-scope show something on the BKLT_SCL/SDA when press backlight adjust keys?

"one thing i noticed is when i connect the display i get around 11.9v instead of a 12.9 when i disconnect the display i get 12.8 volts or so"
Where???

Don't forget PRAM reset...

 

[Gmorb]

bklt_en_r is 3.3v

i get 12.9v now on pin 3 and 4 of q7700 but i was also getting 11.9v at one point when screen was connected seems to have gone away.

i did multiple pram resets even smc reset nothing has changed.

i do not own an o-scope sadly.. I did however boot into OS and pressed the brightness adjust keys and it would indicate it was going up and down but no backlight of course.

 

[larossmann]

Measure voltage on pin 3 and 4 of J8300 with the LCD plugged in and please tell me you are using a 2015-2016 LCD as 2013-2014 or 2012 won't work properly with this year.

 

[Gmorb]

I get 3.7v on those pins and im pretty sure its the original display. Unless someone swapped it.

 

[larossmann]

These are pulled up by a 5v power line with two pullup resistors, so 3.7v is a bit on the low side. what about without screen?

 

[2informaticos]

12V will not pass through Q7700 untill LCD is connected.
Post resistance to ground on both pins of D7710, w/ and w/o LCD connected.
Check the feedback resistors between D7710 and U7700, as traces too.
Better to check all resistors and traces around U7700 and to LCD connector.
Consider change the chip too.
But first of all, be 100% sure to use correct screen!

 

[Gmorb]

pin 3/4 on edp connector are 5.15v without screen connected and resistor's connected to those pins measure fine.

screen unplugged d7710 pin 2 goes from mohm and goes up to kohm then restarts / pin 1 is 11mohm and goes up slowly

screen plugged in does the same as above.

feedback resistors are measuring fine.

checked every other resistor connected to u7700 and they are fine but one thing i did find odd is r7753/r7752 measure 1.6k but when i remove the LED driver they measure what theyre supposed to at 2.4k.

is this normal? i know a lower resistance isnt typically bad but it does seem odd. maybe both my LED drivers are bad?

 

[2informaticos]

Post some voltages at U7700.
Pins 5, 9, 10, 11, 15, 16, 17, 18.

 

[Gmorb]

With screen connected.

pin 5 = 5.15v
pin 9 = 12.88v
pin 10 = 12.88v
pin 11 = 12.68v
pin 15 = 3.7v
pin 16 = 3.7v
pin 17 = 3.3v
pin 18 = 5.15v

update: ok so issue was the video cable was water damaged as well on display side swapped cables now it works!