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Alienware 17 R3 LA-C912P missing voltages

B

Biggtechman

Member
Voltage tests done after power button press.

Pin 67 - 3.3V
Pin 124 - 3.32V
Pin 125 - 3.3V
Pin 37 - 3.3V
Pin 100 - 0.6mV
Pin 106 - 6.0mV
Pin 107 - 0.6mV
Pin 110 - 3.2V
Pin 115 - 3.3V

+3V_PCH_DSW - 3.3V
AC_PRESENT - 3.3V

No change at PBTN_OUT# pin 106 when ON/OFFBTN# in triggered

PM_SLP_SUS# - 8.26Mohm to ground
 
2informaticos

2informaticos

Administrator
Staff member
Looks like KBC problem, but PCH can also impede it to work correctly.
KBC should send out PCH_PWR_EN, to generate +3VALW_PCH; check diode mode there.
Be sure to have good solders at KBC.
Check for broken traces, or moved components.
 
P

piernov

Moderator
Staff member
EC may be waiting for PM_SLP_SUS# to come up. Power sequence isn't clear on that. And of course it's handled by EC firmware so hard to know what it's doing.
 
2informaticos

2informaticos

Administrator
Staff member
Power on diagram (page 56) is very ambiguous.
Is not clear the dependance between PCH_PWR_EN and SLP_SUS#.
Both appear on the same level, without any preference.
 
P

piernov

Moderator
Staff member
Is +3VALW present before pressing power button? +1VALW is never present right?
What's the resistance to ground on +3VALW?
 
B

Biggtechman

Member
Yes, +3VALW is present before and after power button, 13 ohms to ground, measured from cap CM11.
+1VALW is never present, measured from JP2.
 
2informaticos

2informaticos

Administrator
Staff member
You didn't post such a low resistamce for +3VALW before.
Could be PCH, but still a chance to be other chip connected there.

You can try removing chips (leaving PCH at the end), one by one.
KBC should be good, as you was able to read/write it.
 
P

piernov

Moderator
Staff member
If PCH is warming up with only +3VALW present, and +3VALW is 13 ohms to ground, I'm pretty sure the PCH itself is partially shorted somehow, and it would also explain why PM_SLP_SUS# doesn't come up. In my opinion next step would be replacing the PCH (if you have a BGA rework station).
 
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