Macbook A2338 820-02773 No Display

[Instafixx]

Device came in as Dead.

Thermal Scanning showed UP900 heating up. Replace it. Device turns on now. But no image and backlight.
Getting image on external display. Sensor Issue ruled out as LID Open/Close resulting in external display on/off.

 

[2informaticos]

What customer said about fault appearance?
Check JP600's power rails, with LCD connected.

 

[Instafixx]

I just checked PP3v3_s2 is 2.2V at LC710.
Removed LC710 its 3.3V at P3V3S2_SW.
Replaced UP900 just in case - still the same.

 

[2informaticos]

Check if all RC709-13 resistors have correct value.
Also check 3V3_S2 in diode mode; compare with good board.

 

[Instafixx]

RC709 15.5 Ohms
RC710 0.3 Ohms
RC711 2.2 KOhms
RC712 30kOHms
RC713 27.6 Ohms

 

[Instafixx]

Replaced UC710. Still no effect. Removed RD710 now 3V3_S2 is 3.3V.
Shockingly no line on RD710 is shorted thought.

Still no display
Both Pins of RP700 has 3.3V
But EDP_PANEL_DISCHARGE is 0V . Bad QP700

EDP_PANEL_1V8_EN present

 

[Instafixx]

Replaced QP700. Still the same

 

[2informaticos]

Do you have correct 3V3_S2 voltage, with all components soldered back?

 

[Instafixx]

No. I get 2.2V with all components soldered back.
What should i do ? Please guide.

 

[2informaticos]

"Removed RD710 now 3V3_S2 is 3.3V"
Then the problem is on 3V3S2_WLBT line...

 

[Instafixx]

But why no display?
Disconnecting the RD710 should bring Display ?

 

[2informaticos]

Did you check all JP600 voltages?

 

[Instafixx]

With RD710 Removed
PP3v3_S2 is 2.5V - (No Shorts injected voltage too)

PP5V_CAM is 5V
PP5V_SW_LCD_CONN 5V
EDP_PANEL_1V8_EN 1.8V
I2C_CAM_1V8_SDA /SCL 1.8V
I2C_ALS_1V8_SCL / SDA 1.8V
I2C_MLB2JERRY_3V3_SCL/SDA 2.5V

 

[2informaticos]

"Removed RD710 now 3V3_S2 is 3.3V"
................................
With RD710 Removed
PP3v3_S2 is 2.5V"
???

 

[Instafixx]

Yes. i dont know how - but it has not dropped

 

[Instafixx]

WithRD710 Removed.

With LCD Connected 3v3_s2 is 2.5V. (Goes upto 3.3V briefly for 1 Second.)

Without LCD Connected 3v3_S2 is 3.3V Stable.

Replaced UP701 as well. Just in case. Still no display

 

[Instafixx]

I am so confused with this device.
Now will LCD connected i am getting 3.3v Stable- but still no image/backlight.

Please help me out here

 

[2informaticos]

What about 5V_SW_LCD_CONN and LPDP_INT_HPD?

 

[Instafixx]

5V_SW_LCD_CONN is 5V
LPDP_INT_HPD is 0V - No Shorts

 

[2informaticos]

LPDP_INT_HPD should go high (1.2V); if not, CPU can't detect internal LCD.