820-4924 - green light, no liquid damage, sudden shutdown.

[Rozakis]

Hello guys,

I got a 820-4924 macbook that has no signs of liquid damage. The customer brought it because it was shutting down out of nowhere. What should I measure first?

Thank you

 

[2informaticos]

First of all check 3V42 and PPBUS_G3H.
Do you get amber light on Magsafe connector?
Next check 3V3_S5/SUS.
ALso check for any pulse on big coils.


BTW, use Magsafe 2 charger, not 1 --> 2 adapter.

 

[Rozakis]

Hello,

amber light on Magsafe connector OK. PPBUS_G3H 12.51V, pp3v42 3.39V.

I don't know what the /SUS part in 3V3_S5/SUS is, can you explain?

Also, I have no oscilloscope to check for pulses... is there any other way?

Thank you

 

[Rozakis]

Thank you for clearing that up. Big coil L7520 seems to give a tiny voltage 0.02v at initial contact, but then drops to zero. Big coil L7130 is 12.50V.

Measured PP3v3_s5 is 3.32v and _SUS is 0V


Kind reminder, the Macbook is not steady. Sometimes it will not boot at all; other times it boots but shuts down after some seconds and other times it boots into the operating system and can work for several minutes.

 

[2informaticos]

Try if works on SMC bypass mode.
Is that dropped machine?

 

[Rozakis]

Client says it has not been dropped but who knows, right? Unfortunately, even in SMC bypass mode it does the sudden shutdown...

 

[2informaticos]

Try only MLB on the desk; RIO board disconnected.
Just use an USB mouse for test, or USB OSX with Link LED.