820-4924-A Not turning on 2015

[maazkamani]

Liquid Damage Macbook retina 2015

green light no power


ultrasonic cleaned and made sure it was dry

plugged it in and while measuring smoke came out of the board

q7560 had a hole in it

replaced it with 2013 board (slightly different part number)

anyways same thing just the light nothing

pp3v3_s5 is not constant on L7560


ppbus_G3H is 12.57

 

[dukefawks]

Q7560 was obviously dead and U7501 is dead too likely. There is also a good chance the 3v3 bus went high due to the shorted FET. What is resistance to GND on L7560? Replace U7501 if resistance looks ok.

 

[maazkamani]

red prob on ground
0.123 in diode


0.6k in regular resistance

 

[maazkamani]

pin 2 on u7501 is short to ground

removed and still short

 

[maazkamani]

ok so i injected voltage to that pin and other connected components. nothing getting hot

removed l7520 and short gone. i thought it was the coil. i was obviously wrong
p5vs3_vsw had the short rail

removed q7520 and short gone

now replaced that, and u7501

now getting 3.3v constant and cpu getting 1.7v

but nothing on display with brand new battery plugged in

feel so close but yet so far

 

[dukefawks]

Yeah, my bet is on that 3V3 went high and killed stuff on that rail. Does a USB mouse light up when plugged in?

 

[maazkamani]

No it doesnt

 

[dukefawks]

Bleh . Give the board a good inspection for corrosion, but I suspect 3V went high. There is so much stuff on the 3V rail that it is not practical to fix this.

 

[maazkamani]

could it be bios?

 

[maazkamani]

put on ultrasonic and now i hv light on mouse

 

[dukefawks]

Is there an image? Check with flashlight to back of Apple logo to see if it is a backlight issue.

 

[maazkamani]

No image. Solid black. 5v on the bklight

i know these things have low heat but not fan spin either

and Caps lock doesn't light up

 

[dukefawks]

You mean 5V on L8300? Anything on C8300? Fan does not spin on these till they get pretty hot.