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MacBook A2338 820-02020

I

iFix

Member
I have this A2338 it was liquid damage in multiple places on the board. I removed the corrosion, resoldered all broken connections, and rewired some. The laptop is powered on but the backlight comes on for only 1sec and turns off, and still running and boots up on external. I replaced UP800, QP801, and QD530 cause there was corrosion around them and I rewired the broken lines. I also rewired RC100 and RC120 cause they were damaged. I'm getting voltage up to QP801 pin 5, but no transfer to the other side of QP801, only 1-2v, and drops completely.

Any suggestions?
 
I

iFix

Member
Yes, I tried a brand new LCD. It shows a picture with the backlight normal for a second and then loses all
 
I

iFix

Member
UP710 measurements

pin 1 VDD 1.8v stable not losing voltage
pin 2 LCD_PWR_EN I get 1.8v and loses voltage when it's going to flash the logo
pin 3 PMU_SYS_ALIVE 1.2v stable not losing voltage
pin 4 EDP_PANEL_PWR_EN 1.8v and then losing voltage
pin 10 EDP_PANEL_DISCHARGE stable at 1.8v
pin 11 EDP_PANEL_1V8_EN 1.8v and then losing
pin 14 EDP_BLC_5V_EN just 1.8v and losing

UP710 i already replaced
 
I

iFix

Member
PP3V3_SW_LCD_CONN 3.3v but it drops
LPDP_INT_HPD 1.1 v and it drops
RP620 no corrosion all clean there
 
2informaticos

2informaticos

Administrator
Staff member
Then image disappear too, is not just backlight problem.

Corrosion affects more things.
Possibly accumulated crap under some BGAs.
 
I

iFix

Member
Yes as usual. I replaced also UP710 because there was around it some liquid damage. Also there was some corrosion on the Audio circuit, but not sure if that can affect the image and backlight.
 
I

iFix

Member
Update:

PP3v8_AON 3.8v
PP3V3_AON 0v - diode 369
PMU_ONOFF_L - 0.14v - diode 350
PMU_RSLOC_RST_L - 0.14v Diode 325


VSS_ANA_MPMU 0.9v , should be 0v as per schematics note
PP1V8_AON_MPMU - 1.8v on pin 1 R8410
PP1V8_AON_MPMU - 0v on pin 1 C8350
These are strange readings cause Pin 1 on C8350 and R8410 are together



TPT_MPMU_BOOST_UVLO_L 1.7v

Looks like a U8100 issue, but no liquid went inside. Could it be Y8301 (on BW is labeled Y8302?

Any Ideas?
 
2informaticos

2informaticos

Administrator
Staff member
"strange readings cause Pin 1 on C8350 and R8410 are together"
Broken trace?
Did you check for continuity in buzzer mode?
Also check pin 1/R8324 voltage.
 
I

iFix

Member
I'm not sure if the schematic was good. This BW I got is 820-02020-10, but now I found the 09 version, which shows that C8350 and R8410 are not connected on pin 1, and on the 09 version, they are marked R8410 and C8312, which matches the schematic. R8324 is 0v, not coming from that side the voltage
 
I

iFix

Member
0v with a disconnected audio cable.

with removed U8440 I get 1v on PMU_ONOFF_L and PMU_RSLOC_RST_L. Do i change U8440?
 
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