A2485 820-02100-11 issue

[loic2907]

Hi,
On this motherboard there was liquid damage.

Pin 6 of UR200 was not connected
Remplace RF242 too.

Now I have 5V 0.02A on the USB C meter with USB C port (cause magsafe charger no light).
Amps goes to 0.16 when pulse.

Voltage I have :

• LDO of CD3217B12
  • PP1V5_UPC0_LDO_CORE 1.5V
  • PP3V3_UPC0_LDO 3V
• PPHV_INT0_AONSW 5V
• PPVBUS_USBC0 5V
• PP3V8_AON 3.8V
• PP1V8_AON 1.8V

I have pulse (see picture attached for timing pulse) on :

• PP1V8_S2 1.8V (seems that U7700 shorted it to ground when it's LOW)
• PP1V2_S2 Only 0.6V
• PP1V2_AWAKE 1.2V
• PP1V8_AWAKE 1.8V

I have nothing on :

• PP5V_S2SW_USBC01
• PP3V3_S2
• PP3V3_AON

I changed the 3 CD3217B12 from M1 A2337 donor.. Behavior is the same
Nothing is hot at the thermal camera

I am running out of idea, if someone has will send some love

 

[2informaticos]

There must be something else affected by corrosion.
Check U8100 and U7700 LDOs.

PPBUS_AON exact voltage?
It is stable?

 

[loic2907]

Hi, sorry for late, need to do some other stuff for customers.

// means that this is not on the boardview, and not connected in schematic

So PPBUS_AON is 12.291V Stable

For U7700 LDOs :

1. Input LDOs
   • PP1V2_S2_SPMU connected to PP1V2_S2 : 1.2V PULSE
   • PP3V8_AON_SPMU_LDO1 : 3.8V STABLE
   • PPVIN_LDO2_SPMU : //
   • PP1V8_S2_SPMU_LDO3 connected to PP1V8_S2 : 1.8V PULSE
   • PPVIN_LDO4_SPMU : //
   • PPVIN_LDO5_SPMU : //
   • PPVIN_LDO6_SPMU : //
   • PP3V8_AON_SPMU : 3.8V STABLE
2. Output LDOs
   • PP0V72_S2_VDDLOW_REG connected to PP0V72_S2_VDDLOW : 0.74V PULSE
   • PP3V3_S2_ENET_1G_REG : //
   • PPVOUT_LDO2_SPMU_REG : //
   • PP1V2_AWAKESW_BLC_REG connected to PP1V2_AWAKESW_BLC : 0V, STABLE → 66Omh to ground
   • PPVOUT_LDO4_SPMU_REG : //
   • PPVOUT_LDO5_SPMU_REG : //
   • PPVOUT_LDO6_SPMU_REG : //
   • PP1V8_AON_SPMU : 1.8V STABLE
   • PP1V2_AON_SPMU : 1.2V STABLE
   • PP1V5_AON_VCORE_SPMU : 1.5V STABLE

For U8100 LDOs :

1. Input LDOs
   • PPVIN_LDO0_MPMU : //
   • PP3V8_AON_MPMU : 3.77V STABLE
   • PP3V8_AON_MPMU_LDO3 : //
   • PP3V8_AON_MPMU_LDO4 connected to PP3V8_AON_MPMU : 3.77V STABLE
   • PP1V2_S2_MPMU connected to PP1V2_S2 : 1.2V PULSE
   • PPVIN_LDO6_MPMU : //
2. Output LDOs
   • PPVOUT_LDO0_MPMU_REG : //
   • PP3V3_S2_UPC_REG connected to PP3V3_S2 : PULSE but not at 3.3V (check picture attached)
   • PP1V8_S2SW_CLVR_VDDC1_MPMU_REG connected to PP1V8_CLVR_VDDC1 : 0V → More than 1kOhm
   • PP1V8_AWAKE_PCC_REG : //
   • PP3V3_AON_REG connected to PP3V3_AON : 0V → More than 1kOhm
   • PP0V8_S2_CLVR_VDDDIG_REG connected to PP0V8_S2_CLVR_VDDDIG : 0.74V PULSE
   • PPVOUT_LDO6_MPMU_REG : //
   • PP1V8_AON_REG connected to PP1V8_AON : 1.8V STABLE
   • PP1V2_AON_REG connected to PP1V2_AON : 1.2V STABLE
   • PP1V5_AON_VCORE_MPMU : 1.5V STABLE

Thanks in advance

 

[2informaticos]

U8100's VLDO1 (3V3_S2) must be stable, if VIN_LDO1 is stable (3V8_AON).
If not, there may be a problem with U8100, M1 CPU, or other component connected there.
I recommend to try reballing U8100 first.

 

[loic2907]

Hi,
Successfully reball U8100 and U7700.
There was not oxydation under these chips
Nothing more, still pulse

 

[2informaticos]

Check all seconday power supplies.
Maybe PMUs detect a problem and cycle power.

You may also have problems with M1 CPU.

 

[loic2907]

Thanks for your reply, do you have some informations about secondary power supply ?
I work on windows laptop, mac is a bit different ^^
Thanks

 

[2informaticos]

Any voltage generated from main power supply using a buck converter.
Same theory applies like on any other laptop.

Look at the coils from the MLB, the ones having a MOSFET connected to PPBUS_AON; for example L/Q5800/20/40.
There may be also power chips which include the MOSFETs; like L/U9400/20, L/U9500, L/UC260, L/UF800.

Many low level voltages are generated from 3V8_AON; for example the small coils around U7700 and U8100.
There you can't find direct short to PPBUS_AON, but can block the power sequence.