A2485 MacBook Pro / 820-02100-A board / 5v .11a / Logic board failure /

[zeydullak]

Hello guys,

We have a A2485 MacBook Pro that is using only 5v and .11a, when connected nothing happens at all.

The customer said it is not water damage and some type of other failure.

Here are some voltage readings of the main power lines.

PPBUS_AON -> 12.3v
PVBAT_AON_CHGR_R -> 12.30
PPBUS_NAND0 -> 12.30
PPBUS_AON_LUXE -> 12.30

Please advise on what we should do next.

Regards,
Zeydulla.

 

[2informaticos]

Don't waste time checking the same power rail in various points.
Aren't all these lines PPBUS_AON???

What about 3V8_AON and U8100 LDOs?
Any other voltage detected on the MLB?
Check U7700 LDOs too.

 

[zeydullak]

3V8_aon -> .0v
--------------------------------
PPVDD_ECPU_AWAKE -> .0V
PP0V81_S1_SRAM -> .0V
PP1V8_S2SW -> .0V
---------------------------------
PPVDD_AMPH0_S2SW ->.0V
PP1V2_AWAKE -> .0V
PP0V575_S1_VDDQ0 -> .0v

 

[2informaticos]

You can't get more voltage without 3V8_AON.
Did you check it on diode mode?

 

[zeydullak]

____________Customer_Board____________

PP3V8_AON -> .0001

____________Working_Board____________

PP3V8_AON -> .3516

 

[2informaticos]

Short to ground.
Use voltage injection method to find the culprit.
As always, start with just 1V; set amp limit to max first.