820-00840-a

Mac Tech

Member
This board came from another service, they repaired it and changed the U7100 but it turns off after power on.

I changed U7100 to discard but now it stays at 20V and 267 ma.

PPVCCCPU_S0G is 0V.

I have ALL_SYS_PWRGD 3.2v

CPUVR_PWM2 2.49V
CPUVR_PWM1 2.49V

I am missing PM_PCH_SYS_PWROK
 

Mac Tech

Member
L7370 : 1V

I haven't tried bios yet.

The equipment arrived on, only it turned off and showed Chinese letters
 

2informaticos

Administrator
Staff member
If board stopped to turn on after you've changed U7100, recheck your job; possibly knocked off components, bad solders.
 

Mac Tech

Member
ok, I saw that it had a consumption of 200ma fixed. Then I put the thermal camera and it heats me R7733.

I remove U7700 and now the machine changes to 19V and consumption of 6ma.

I already have the voltage of PM_PCH_SYS_PWORK 2.95V

PPVCCOPC_S0G beeps me to ground, but on ohm scale it's 060.1
 

2informaticos

Administrator
Staff member
Low resistance to ground on CPU coils is normal.

Did you apply power without U7700???
The board may be trash now...
 

2informaticos

Administrator
Staff member
Big error; don't do that ever again!

Change Q7730 and U7700.
Be sure all traces and surrounding components are good; pay atention to R7731/33 and R/C7730.

Then pray half hour and test the board again with power...
 

Mac Tech

Member
the problem was Q7730.

Now the board when connecting the battery flex does not finish turning on, it restarts the system.

When disconnecting the flex it turns on without problem.
 

Mac Tech

Member
Does it make any difference that the machine when turned on without the battery flex, does not show an X in the battery icon when showing the login?

I have put another plate and I have done the same to remove the flex from the battery and it shows an X where the battery icon is.
 

Mac Tech

Member
Big error; don't do that ever again!

Change Q7730 and U7700.
Be sure all traces and surrounding components are good; pay atention to R7731/33 and R/C7730.

Then pray half hour and test the board again with power...

Before finding the fault here, I had changed the Bios for another of the same model only from a different manufacturer.

Could this have affected something?

Should I reprogram new Bios with your serial number?
 

2informaticos

Administrator
Staff member
Put back original BIOS; or use known good dump.

Check voltage and diode mode to ground on SCL/SDA lines of battery bus.
 

Mac Tech

Member
Other MLB recognizes and charges this battery?
R: I have put a board from another model but a1708 in the top case that has the bad board and everything works perfectly, it charges well.

Inspect both ends of battery data cable.
R: I already changed the flex of the battery identification.
 
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