820-00165 Green/Amber light, no fan spin.

[gfosterCA]

Board removed, testing with DC-in board, fan only, using 85W magsafe 2 power adapter.

PPBUS_G3H - 8.6v (8.596)
PPBUS_S5_HS_COMPUTING_ISNS - 8.6v
PP3V42_G3H - 3.4v
P3V42G3H_SW - 3.42v

L7560 - 3.35v
L7520 - 0v

P3V3_S5_DRVH - 3.38v @ Q7560 pin 3
P5V_S4RS3_DRVH - 0v @ Q7520 pin 3

Help is very much appreciated!

 

[2informaticos]

First of all, welcome to the forum!

Any fault history available?
Post SMC_ADAPTER_EN, PM_BATLOW_L, PCH_DSWVRMEN, S5_PWRGD, PM_DSW_PWRGD, 3V3_SUS voltage.

 

[gfosterCA]

First of all, welcome to the forum!

Any fault history available?
Post SMC_ADAPTER_EN, PM_BATLOW_L, PCH_DSWVRMEN, S5_PWRGD, PM_DSW_PWRGD, 3.35v voltage.

Thanks for the welcome!

Customer reported machine just stopped booting. No real evidence of liquid damage or major corrosion that I can see.

SMC_ADAPTER_EN = 3.39v
PM_BATLOW_L = 3.35v
PCH_DSWVRMEN = 3.26v
S5_PWRGD = 3.40v @ U7501 pin 20, and right side of R8141
PM_DSW_PWRG = 3.42v
3V3_SUS = 3.35v

 

[2informaticos]

Trigger SMC_ONOFF_L and check for drop pulse at PM_PWRBTN_L (at same time).

BTW, write directly on the reply box, instead of clicking Reply button.
I don't see any reason to quote an entire post, visible few centimeters above.
Please, maintain the forum aesthetic...

 

[gfosterCA]

Apologies on the poor reply form!

I'm assuming triggering is grounding SMC_ONOFF_L.
If so, I am seeing :
PM_PWRBTN_L drop from 3.41v -> 0.34v

 

[2informaticos]

Touch the ground only a moment, like when press the power button to start.
Now check for pulse at PM_SLP_S4_L (at same time also).

 

[gfosterCA]

Momentary drop (as other pad is grounded) to 0.34v

 

[2informaticos]

Do you mean PM_SLP_S4_L drops to 0.34V when trigger SMC_ONOFF_L???
It should pulse high, not droping...

 

[gfosterCA]

My apologies - 0v in both states.

 

[2informaticos]

Must be something PCH related.
Check PM_RSMRST_L and the 4 PCH's RTC signals.

 

[gfosterCA]

PM_RSMRST_L = 3.32v
PCH_CLK32K_RTCX1 = .37v
RTC_RESET_L = 3.34v
PPVRTC_G3H = 3.35v
PPVOUT_S0_PCH_DCPRTC = 1.58v

 

[gfosterCA]

Just happened across a short at C1420. Pulled the cap and short still exists.

 

[2informaticos]

There are many more components connected.
If pure short, you can use voltage injection to detect the culprit.

BTW, read this thread about RTC signals...

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

 

[gfosterCA]

Great read, thank you.

Looks like L1275 is shorted. Also getting shorts at C1280,C1280 and L1280.

Before I go too far down the rabbit hole, is this a good indication of a CPU that's toasted itself ?

 

[2informaticos]

One coil measure short as normal.
It never can generate a short to ground.
Remove the coil and see where the short to ground remains.

 

[gfosterCA]

Morning. Pulled L7630, short remains on P1V05_S0_REG, showing heat via thermal cam in CPU region.

 

[2informaticos]

Bad news, dead CPU...

 

[gfosterCA]

Thanks for the guidance on this. Have another with what I suspect to be an SMC problem. Will tackle that in a new thread.