820-3437-B No fan, no water, MG orange

[MaxFix]

Hi there,

No water damage. Board inspected, nothing looks suspicious.
SMC reset - MG flashes green to orange.
SMC bypass - gave me half a fan spin once but not anymore.

L7701 - 0V
L3095 - 0V
L7130 - 8V
L7520 - pulse around 0.5-2V
L7560 - 3.2V
L7430 - pulse 0.5V
L7630 - pulse around 0.4V
L7310 - pulse 0.01V
L7320 - pulse 0.01V

Please advice how to proceed.

Thanks!

 

[2informaticos]

"L7130 - 8V"
Can you post exact voltage?
8.2V and 8.5V is completely different thing!

ALL_SYS_PWRGD pulses?

 

[MaxFix]

Apologies. Point well taken.
L7130: pin 2 - 8.6V, pin 1 - 8.16V
ALL_SYS_PWRGD - pulses 0.6 - 1.3V

 

[2informaticos]

"L7130: pin 2 - 8.6V,"
Keep this reading; there is DC output.
The other is irrelevant.

If ALL_SYS_PWRGD pulses, then all big coils should pulse too; not the CPU ones maybe.
Check U1950 area; any pulse at pin 3?

 

[MaxFix]

U1950 no pulse at pin 3

 

[2informaticos]

Check for pulse at pin 7; it should appear first.

 

[MaxFix]

Pin 7 - pulse.

 

[2informaticos]

Trigger SMC_ONOFF_L repeatedly and check for pulse at pins 5/6 of U1950.
If both pulse, pin 3 should pulse too.

 

[MaxFix]

Triggered SMC_ONOFF_L repeatedly.
PIN 5, 7 of U1950 - pulse
PIN 3, 6 - no pulse.

 

[2informaticos]

So SMC_DELAYED_PWRGD no pulse at all?
Could be PCH, or SMC issue.
Short pins 5/6 and check for pulse at pin 3 and VCORE.

 

[MaxFix]

SMC_DELAYED_PWRGD no pulse at all!
pins 5/6 shorted - no pulse on pin 3.
VCORE you mean L7310 and L7320? also 0V

 

[2informaticos]

First, check for short and voltage pulses at Power FETs, page 58.

You can try to heat SMC and PCH with good flux.
If no result, change SMC.

 

[MaxFix]

Checked for shorts at power FETs - no.
I am going to send it to another shop that specialises on MB repairs before I mess things up with SMC and PCH reflow.
Thanks for your help. I will post if they manage to fix it.