820-3787 no image external/Internal

[BCN_Techs]

History;


Broken display, changed it and it worked for 20 minuts. Now chime CPU is heating but GPu is cold.

Things i already tried

- changed U9300
- Reflow U9600 and U9650, No change.


J8300 pins 28-30 0V.
GPUVcore 0V


No line seems to be shorted.

 

[2informaticos]

No reason to measure J8300, if no GPU VCORE present.
Image MUST appear before the backlight.

Post basic voltages for U9300; pins 17, 16, 25, 38.

 

[BCN_Techs]

17 - 12.6v
16 - 5.0v
25 - 5.0v
38 - 0v

 

[2informaticos]

So GPU VCORE is not even enabled.
Check GPU rail sequencing at page 66...

 

[BCN_Techs]

P1V8GPU_EN is missing ans as than all rail go after this one are missing too. I see it is generated by U9600. Reflow? Can it be take from any board or it's like SMC and must take it from same board?

 

[2informaticos]

Do you get GPU_PGOOD1?

 

[BCN_Techs]

i cant find where ti measure it. There is no component or point on GPU_PGOOD1

 

[BCN_Techs]

if it's same as PP3V3_S0GPU than i am getting 0V

 

[BCN_Techs]

PP3V3_S0GPU_FET that seems to be same line you are asking me is pulsing to 0.5 V when magsafe connected and than goes down


P.S: All measerments are made with LCD disconnected

 

[2informaticos]

What's the reason to measure video signals without LCD?
Post Q8090 voltages.
Check diode mode to ground at =PP3V3_S0GPU_FET.

 

[BCN_Techs]

Q8090

1,2 - 0V
3 - 3.3V
4-7 - 3.3


Diode mode for PP3V3_S0GPU_FET 0.472


Now LCD is connected

 

[BCN_Techs]

Just have checked with display connected values u asked me before are same.

 

[2informaticos]

Missing =P3V3GPU_EN?
I supposed to be present, as you said
"P1V8GPU_EN is missing"
which is next AFTER 3V3GPU...

 

[BCN_Techs]

P3V3GPU_EN is present 3.3V

P1V8GPU_EN is missing.

 

[2informaticos]

Then post Q8092 voltages.

 

[BCN_Techs]

P3v3gpu_en 3.3
p3v3gpu_en_l - 0v

 

[BCN_Techs]

Sorry wrong previous two measerument. I have p3v3gpu_en_l 3.3V and P3v3gpu_en is 0V

 

[2informaticos]

"P3V3GPU_EN is present 3.3V
--------------------
P3v3gpu_en is 0V"
Please...

 

[BCN_Techs]

P3V3GPU_EN is missing. In openboardview when you search for P3V3GPU_EN it mark you P3V3GPU_EN and P3V3GPU_EN_L so i measured and got 3.3.

Here is correct value:


On Q8092

Pin 3 ( P3V3GPU_EN_L) is 3.3 V
Pin 1 (P3V3GPU_EN ) is 0V

 

[2informaticos]

Did you check SMC_LID level?
Nothing change if connect external monitor?