820-2390 no green light, not booting after water damage.

[2informaticos]

Do you get correct voltage at C7771?
Don't forget to check it, before sending the machine out to the client.

Check current and voltage sensing circuits from page 45.
U7000, pins 17/18 have correct 20 ohms, as per schematic.
Inspect for corroded traces/resistors under microscope around affected areas.

When in SMC bypass, do you get voltage at all big coils?

 

[BCN_Techs]

getting 1.1V pm C7771. This was first i checked.


There is no visible corrosion except of C7115 and a couple of near components. Anyway will try to clean one more time in ultrasonic and back once finish. THanks.

 

[2informaticos]

Ultrasonic bath can clean corrosion, but will not rebuild broken traces.
You have a problem with some I/V sensor; like PBUS_VSENSE, or other from mentioned page.

 

[BCN_Techs]

When smcbypass i am getting.

L7100/01 0.9V


CPU and both GPU are heating.


I have checked whole board and cannot find anything.


Also from page 45


PBUSVSENS_EN 0V is that normal?


Q5315

4 - 8.40
5 - 8.30
6 - 8.25

3 and 2 0V



About PPBUS 8.4 is that normal? Does it likes 820-00165 that mean smc issue?




And CPU Vcore side sensor:

U5388 (seems be ok)

Pins 4-5-6 8.4V
Pin 3 3.4V




P.S: IMVP6_IMON must be 0?

 

[BCN_Techs]

Also i am checking 1 wire and on R6912 getting 6V on pin 1 and 0 on pin 2. Resistance is ok 330KOhms,

 

[2informaticos]

You cannot have more than 3.3V at U5388 output, unless it is bad!
Its output is related with voltage drop across R5388.
For example, 5A will generate 2.5V at C5335.
When board is off, you should have 0V there...

 

[BCN_Techs]

sorry, it's 0V all other measerements are ok.

About ppbus 8.4 and one - wire circuit any wrong thing?


also why i am getting this: "Also i am checking 1 wire and on R6912 getting 6V on pin 1 and 0 on pin 2. Resistance is ok 330KOhms,"


Thank you

 

[2informaticos]

Nothing wrong with R6912, it has correct voltages.
Usually U6915 is the "bad guy" there; but Q6910 fails too.
Post their voltages...

 

[BCN_Techs]

Finally i replaced U6915, Q6915,Q6910, U7000 (again) and many other and now computer starts. The only problem still remains is that its not charging. No green light. It detects magsafe because battery in status bar change status but not charging.


Seems one wire issue but i cant find nothing more to replace.

 

[BCN_Techs]

U6915 was the problem. seems donor u6915 was bad too.

THank you very much

 

[2informaticos]

You don't need to change so many components.
Just read their voltages and interpret the values...