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820-00840-A No boot

S

sourcensolutionsonline@gm

Member
This Macbook A1708 A820-00840 Came in today customer stated that some water spilled on it , it was working then suddenly shut down. So I inspected the board and found no water damaged wheresoever on the board , as I connected amp meter i am getting 20v but nothing else , I proceeded get the motherboard out to test and found diode mode readings are fine but PPBUS_G3H 0.111V I checked U7000 For short and all was good I checked F7000 in continuity mode and it was fine and in diode mode 0.404 ohms , I have also checked U6990 for short and all diode mode readinds are fine but -PP3V3_G3H is 0.111V

May I please get some help?
 
2informaticos

2informaticos

Administrator
Staff member
USB-C power inputs switch to 20V without 3V3_G3H???
That's very strange; was the battery disconnected?

Test the board alone on the desk, only charger connected.
Do you get 20V at R7020?
 
S

sourcensolutionsonline@gm

Member
Sorry I Have made a mistake regarding the 3V3_G3H , this power rail is ok i am getting the 3.73V when USB -C is connected and also getting 20V at R7020 with battery disconnected but still PPBUS_G3H is not present.
 
S

sourcensolutionsonline@gm

Member
Here are the basic voltages of U7000

P_IN = 20.30V
AUX_DET = 4.8V
VDDA = 5.07 V
VDDP = 5.07V
AUX_OK.= 3.375V

CHR_A/BMON,?

I could not find any related components connected to those power rails since they are output ,Would you please give me any referral of any components connected to those two power rails that i can find out what their voltages are ?

Thank you very much
 
S

sourcensolutionsonline@gm

Member
Right , I will definitely use the pdf sheet from now on ,

Now here's what I found at CHR_A/BMON very unstable voltages ,

CHR_AMON = 0.016 Then dropped to 0,011V

CHR_BMON = 0.083V then dropped to 0.0V
 
S

sourcensolutionsonline@gm

Member
Here s what I got when I checked those components

Q7030
TBA_GATE_Q2 = 0.426 OHMS and 0.00V
PPDCIN_G3H_CHGR = 0.527 OHMS AND 20.22V
TBA_GATE_Q1 = 0.792OHMS and 0.011V
TBA_LX1 = 0.378 0HMS and 0.009V
TBA_PHASE1 = 0.378OHMS and 0.008V


R7030
TBA_BOOT1_RC = 0.553 OHMS and 4.75V
TBA_BOOT1 = 0.553OHMS and 4.75V

C7030

TBA_LX1 = 0.378 OHMS And 0.009V
TBA_BOOT1_RC = 0.553 OHMS and 4.75V


Q7040

PPVBAT_G3H_CHGR_REG = 0.406 OHMS and 0.90V unstable
TBA_GATE_Q3 = 0.423OHMS and 0.000V
TBA_GATE_Q4 = 0.378 OHMS and 0.007V
TBA_LX2 =0.379 OHMS And 0.008V
TBA_PHASE2 = 0.379 OHMS and 0.009V

R7040

TBA_BOOT2_RC = 0.549 OHMS And 4.78V
TBA_BOOT2 = 0.549 OHMS And 4.78V


C7040

TBA_BOOT2_RC = 0.549 OHMS And 4.78V

TBA_LX2 =0.379 OHMS And 0.008V

During the inspection I also reviewed all components for corrosion as well as broken or missing but all the components are in mint conditions

Please advice the next step.
Thank you
 
2informaticos

2informaticos

Administrator
Staff member
I was expecting you check resistors ohm value.
Also need to check the MOSFETs between there pins; better to remove and check for open/clos outside.
I didn't say to check against ground.
 
S

sourcensolutionsonline@gm

Member
When I check R7030 and R7040 Pin in ohm , both resistors are giving me the same value 0.4 ohm and The MOSFETs comparing to a known good working board they are giving me the same reading as the good board.
 
2informaticos

2informaticos

Administrator
Staff member
You should check if MOSFETs open/close each channel, outside of board.
Many videos on Internet, about how to check a MOSFET.
 
S

sourcensolutionsonline@gm

Member
I was trying to get some specific video about the MOSFET open and close but i am not coming across a good clear one do you happen to have any good ones that i can go to ?

Thank you very much .
 
S

sourcensolutionsonline@gm

Member
I was trying to get some specific video about the MOSFET open and close but i am not coming across a good clear one do you happen to have any good ones that i can go to ?

Thank you very much .
 
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