Macbook Pro 15" A1707 820-00928-04 no chime,no boot,no image 19.92v 0.900a

[gugutm]

Hi everyone
Please bear with me as I am not yet a pro with some of these issues. Trying to watch a lot of youtube videos and master myself but there are things which I cannot fix and would like to ask for a help from the pro people.
Got macbook a1707 board no 820-00928-04

It had a water damage on couple components, green staff corrosion,
C7680 ppbus _hs_oth3v3, tested for short I believe its okey red prob on ground, getting 2.512kilo om
C7251 ppbus_hs_cpu done the same and getting about the same, 2.506kilo om
U5400 some corrosion, I clear all this places as much as I could with an isopropyl alcohol and tried to power on to see what is going on.

I can see fans spins, but no light on a touch bar, keyboard caps lock not working, no light on a screen I try to connect to hdmi, but not working,

My amp meter shows 19.92v and from 1.161a to 1.166a fluctuating this is when screen was connected and when I disconnected and take motherboard out I am getting 19.97v 0.900a

PP3V3_G3H (R6923 - either side of the 0 ohm resistor) 1.791 kilo om

PPBUS_G3H (F7000, pin # 2) 2.530 and going up kilo om
Here is some s0 rails I just measured
Ppcc_s0_cpu 0.670v this is I believe not okey I think it should be 1.2v correct me if I am wrong

i tried to measure in a resistance mode i believe a c1073 because it is on a ppcc_s0_cpu and on pin 1 i am getting red prog on ground 003.9 om but i know from video that around cpu resistance could be low.

Pp5v_s0 5.1v
Pp3v3_s0 3.3v
Pp3v3_s0_gpu 3.3v
Pp1v8_s0 1.79v

Try to upload as much info as I can to speed up a fix process if it is possible to fix it, read all badcaps forum about this model, also rossmanngroup forum.
looked in wiki done some reasearch but now came to the point i need your help guys please.

many thanks
gugutm

[Stevedb]

Re: Macbook Pro 15" A1707 820-00928-04 no chime,no boot,no image 19.92v 0.900a

Hi did ypu reflow the area where was corrosio do you have pictúres from the area with corrosion it can be thatpads from area where corrosion was not making good contact anymore.

[gugutm]

Re: Macbook Pro 15" A1707 820-00928-04 no chime,no boot,no image 19.92v 0.900a

no i did not reflow it i might need to do it
sorry made a mistake it wasnt u5400 it was u7900 my bad sorry for misleading information i uploaded a picture before and will add what is looks like now

i reflow the u7900 so on the pin 1 i am getting 12,56v on a pin 8 1.2v looks okey . to me

[gugutm]

Re: Macbook Pro 15" A1707 820-00928-04 no chime,no boot,no image 19.92v 0.900a

Any help? please i would really appreciate it

[mon2]

Re: Macbook Pro 15" A1707 820-00928-04 no chime,no boot,no image 19.92v 0.900a

Voltage to ground of PPBUS_G3H?

[gugutm]

Re: Macbook Pro 15" A1707 820-00928-04 no chime,no boot,no image 19.92v 0.900a

Good morning
Voltage to ground of PPBUS_G3H?

power connected and on r6907 pin 1 and 2 12.63v
i tried to measure in a resistance mode i believe cb703 pin1 red prob to ground 000.0 om
i am confused does it mean short
or i am doing something wrong ?

i read another post about this motherboard and you asked the same question so i done on f7000 pin 2 and i am getting 000.0 om

many thanks

[mon2]

Re: Macbook Pro 15" A1707 820-00928-04 no chime,no boot,no image 19.92v 0.900a

Never have power to the board while measuring resistance or diode mode readings.

Remove all power. Meter in resistance mode. Measure the resistance to ground of the same fuse. One probe on one side of the fuse. Other probe to ground. What is the reading?

Then repeat for the other side of the same fuse. We want to check if there is a shorted part and also checking if the fuse is ok.

Next, meter in dc volts mode of 20v or higher or auto adjust setting. Apply the power adapter.

Red probe to the same fuse. Ground probe to ground.

What is the voltage measurement? Repeat with red probe on the other side of the fuse.

[gugutm]

Re: Macbook Pro 15" A1707 820-00928-04 no chime,no boot,no image 19.92v 0.900a

ok I am sorry i will take this in mind never have power while i am measuring resistance or diode mode
please accept my apologies and thanks for help

lets start again
f7000 in beep mode no power red pin 1 black pin 2 beeps and shows 000.5om
f7000 in beep mode no power black pin 1 red pin 2 beeps and shows 000.4om

resistance mode auto f7000 red prob on ground black prob on pin 1 2.550 kom
resistance mode auto f7000 red prob on ground black prob on pin 2 2.550 kom

power on amp meter shows 19.99v 0.880/0.890a
20v dc auto f7000 pin 1 12.56v, pin 2 12.63v

f7001 got same readings pin 1 and 2 12.63v

[mon2]

Re: Macbook Pro 15" A1707 820-00928-04 no chime,no boot,no image 19.92v 0.900a

Is the current draw on the power adapter side instantaneous and spikes to the peak voltage upon connecting (turn on) or does it climb up slowly to the posted values?

[gugutm]

Re: Macbook Pro 15" A1707 820-00928-04 no chime,no boot,no image 19.92v 0.900a

when i plug amp meter it shows 14.58v then jumps to 20.14 1.317 a an gradually, few sec goes to 19.99 to about 0.890a

[mon2]

Re: Macbook Pro 15" A1707 820-00928-04 no chime,no boot,no image 19.92v 0.900a

Fault maybe a defective GPU.

See the case study here:

https://repair.wiki/w/A1707_2016-201...ar_MacBook_Pro

[gugutm]

Re: Macbook Pro 15" A1707 820-00928-04 no chime,no boot,no image 19.92v 0.900a

no this is going be beyond my limits i can try reboil it but not to change , thank you for your help Mon2
shame i could not fix it

[mon2]

Re: Macbook Pro 15" A1707 820-00928-04 no chime,no boot,no image 19.92v 0.900a

Do wait on other comments but a sudden spike of current on the power rail often indicates a shorted / partially shorted component.

TBH - even after investing into a rather high end Seamark BGA rework station (paid more than the car I am driving) - still afraid of the process. Removing BGA devices is a dream with the tool we have as it is fully automated. Recently had the tool calibrated for the proper placement of a fresh device. BGA devices are almost in our comfort zone with this tool but not yet with WLCSP packaged devices which are wafer thin. During the pickup process, the suction nozzle cracked the fresh component due to the travel height action. Still learning.

Do check the EDP_PANEL_PWR_EN voltage to ground as well to confirm the above case. Plan B is to treat this board as a donor board.

[spidertnt]

Re: Macbook Pro 15" A1707 820-00928-04 no chime,no boot,no image 19.92v 0.900a

no i did not reflow it i might need to do it
sorry made a mistake it wasnt u5400 it was u7900 my bad sorry for misleading information i uploaded a picture before and will add what is looks like now

i reflow the u7900 so on the pin 1 i am getting 12,56v on a pin 8 1.2v looks okey . to me

second picture looks like possible burnt pins on the flex display connector ?...when this happens the screen side connector also needs replacement.

The burning usually damages the GMUX chip and it will also need replacement .