Macbook 820-00165 Random Shut Down

[Instafixx]

This one here is weird. The machine works perfectly but sometimes it just switches off suddenly.It can be within 2 minutes or after 2 hours.
When it goes off the fan still spins . Have to long press the power button to switch off the machine and then again have to power on.

There is very little corrosion beside C1004 at the grounding point on the board
C1004 Diode mode readings are 0.018. (Red to Ground)
Also looks like U1930 has some crap underneath it. I am unsure though.

Should we reball the U1930.

 

[2informaticos]

Resolder U1930 properly.
Also clean and resolder U1950.

If CPU core voltage remains, check if CPU_VCCST_PWRGD and PLT_RESET_L goes down then.

 

[Instafixx]

After removing u1930 .The board was corroded below U1930. Fixed the pads and repalced the U1930.
The machine doesnt turn on. Only fan spin. PPBUS is okay.

 

[2informaticos]

If fan spins, board turns on.
Need to find why doesn't boot.

So what about U1950 signals?
Check pins 7 & 3.
Which big coils get voltage now?

 

[Instafixx]

Okay so now i dont have any fan spin. The fan just spins for a second and stops as if its trying to turn on.
Both Pin 3 and Pin 7 have 0 Voltages but it spikes but upto 3.3V and again zero. (This happens continuosly)

Same Voltage Spike Issue at
L7520

L3095 is 0 Volts
L7701 is 0 Volts (NO DISPLAY CONNECTED)
L7320 and L7310 is 0 Volts


[UPDATE] ALL OTHER BIG COILS HAVE VOLTAGE

 

[2informaticos]

All other big coils get stable voltage, or just spike?
Impossible to be stable, if L7520 is not stable.

Pin 3 of U1950 pulsing too, or only pin 7?
Same behavior in SMC bypass mode?

Inspect Q8150 for corrosion.
Remove it and test the board again.

 

[Instafixx]

Yes all other get stable voltage. Like L7560 is a stable 3.3V.

yes both pin 3 and Pin 7 are pulsing.
I dont know how to do SMC Bypass. Can you teach me or give me any link.

Q8150 has no corosion. Removed it. Same Situation

 

[2informaticos]

If pin 3/U1950 pulses, then you must detect pulse at L7310/20 too.
Check PLT_RESET_L for pulse also.

HOW TO collection

I hope this "How to" collection will help our members. I will possibly modify this post in time, if updates available. Trigger SMC_ONOFF_L (PMU_ONOFF_L): It reffers to simulate power button function, when the keyboard is not connected. We need to do this when we work with the board...

boards.rossmanngroup.com

Did you check CPU_VCCST_PWRGD for pulse, after resoldered U1930?

 

[Instafixx]

now no pluse on pin 3 of U1950 its at a constant 0 VOlts. No span spin at all.

PLT_RESET_L is also at 0V.

CPU_VCCST_PWRGD is 0 Volts too

L7520 is also 0 Volts

 

[2informaticos]

Tie together pins 5 & 6 of U1950 and test again.

Did you try SMC bypass?

 

[Instafixx]

Tied up 5 and 6. Now i get random fan spins and even reverse direction fan spins.

If i press the power button i get a fan spins and it stops.

Didnt try the smc bypass yet. Should we try it ?

 

[2informaticos]

Yes, try that...

 

[Instafixx]

Its Still the same.

 

[2informaticos]

Any pulse at CPU_VCCST_PWRGD and PLT_RESET_L?
You should catch pulse at L7310/20 too.

 

[Instafixx]

There is no pulse a L7310/20.

No Voltage at CPU_VCCST_PWRGD and PLT_RESET_L

I got slight pulse at L7320 once - It went upto 0.2 Volts.

 

[2informaticos]

Is recommended to trigger SMC_ONOFF_L and check the reaction then.

If pin 7/U1950 pulses, then ALL_SYS_PWRGD and PM_SLP_S3_L pulse both.
L7630 should pulse too and MUST catch pulse at CPU_VCCST_PWRGD.
If not, you still have a problem on U1930 area.

Do NOT use full AUTO multimeter.
At least set it on DC voltage, in auto range.
An oscilloscope helps better to hunt full peak pulse.

If board pulses every 5s, turning on in SMC byapss will generate higher pulse.

 

[Instafixx]

Pin 7 of U1950 Pulses.

It is set to DC voltage on auto range.

ALL sys pwrgd for is a stable 3.3V for sometime and the ngoes down to zero.

PM_SLP_S3_L pulses.

L7630 Pulses. but CPU_VCCST_PWRGD is 0V.

 

[2informaticos]

"you still have a problem on U1930 area"

 

[Instafixx]

U1930 was the issue indeed. Rework done. Machine working fine now