820-3437 - Green Light But Won't turn on

[menatwork]

The logic board looks pretty clean, however, wont turn on.


PPBUS_G3H - 8.56V
PPVRTC_G3H - 3.3V
PP5V_S5 - 5V
** PP5V_S4RS3 - 0V
PP3V3_S5 - 3.3V
PP3V3_S3 - 0V - No short to ground
PP3V3_SUS - 0V
U7100 = 17/18 - 4Ohms
27/28 - 20Ohms

 

[menatwork]

Pm_batlow_l = 3.3v
pch_dswvrmen = 3.3v
pm_dsw_pwrgd = 3.4v

I forgot to mention: PP3V3_S3 / PM_SLP_S4_L cycling 0 to 2.7 - no short to ground.

 

[JohnB8812]

Does CPU VCore pulse as well?

 

[2informaticos]

Then all S3 voltages should pulse too.
Check if PM_SLP_S3_l pulses; if yes, all S0 voltages (maybe not CPU VCORE) should also pulse.

 

[menatwork]

PM_SLP_S3_l = Pulsing 0 to 2.7V as well
PPVCC_S0_CPU = Pulsing

 

[menatwork]

I tried SMC bypass the fan spins and stop.

 

[2informaticos]

Check if all voltages from page 58 try to appear.
Also test the MLB alone, disconnecting LIO flex.

 

[menatwork]

U8010
PIN 2/4 = 3.3V
6 = 0V (PP3V3S3_EN)

U8000
PIN 2/4 = 3.3V
1/3/6 = 0V

U8020
PIN 2/4 = 3.3v
PIN 1/3 = 3.3v
PIN 6 = 3.3v


u8050
PIN 2/4 = 3.3v
1/3/6 = 0v

 

[2informaticos]

"6 = 0V (PP3V3S3_EN)"
Doesn't pulse high?
It should, when PM_SLP_S4_L pulses; output pins must pulse too, check for short.
Check the same on all these chips.

"Also test the MLB alone, disconnecting LIO flex."

 

[menatwork]

PM_SLP_S4_L = Pulsing 0 to 0.36V
PP3V3S3_EN = Pulsing 0 to 0.200V and 0.689 and 1.229 and 2.4V and Back to Zero.

Tested without LIO FLEX as well.

 

[JohnB8812]

Inspect near U6100 for corroded resistors/probe points. Might not be a bad idea to test with a new BIOS as well. Keep old one do not lose it!