820-01958 Air A2179 with power drain problem

[sekidata]

This A2179 Air arrived dead after customer dropped it. One of its USB-C ports showed 20V, the other 5V. I replaced both CD3217s from an identical donor board and the machine appeared to work fine.
However, when the computer is shut down, the battery continues draining (about 10-15% in 6 hours). Can you help troubleshoot this behavior?

 

[2informaticos]

Check page 66 (Power FETs) all S3 and S0 voltages must go off when turned off.

 

[sekidata]

I measured several rails from page 66 and some others. Does this look as it should?

Not energized:
PP1V1_S3: 0
PP0V6_S3: 0
PP1V8_S3: 0
PPVCC_S0_CPU: 0
PP1V8_S0SW_CPU: 0
PM_SLP_SUS_L: 0
PM_SLP_S3_L: 0

Energized:
PPBUS_G3H: 11.8
PP5V_G3S: 5.1
PP3V3_G3H: 3.3
PP3V3_S5: 2.0
PP1V8_G3S: 1.8
PP1V8_PRIM_PCH: 1.0
PPVOUT_S0_KBDBKLT: 5.1
PP1V05_PCH_CPU: 0.7

 

[2informaticos]

Looks good.

Only G3H, SLPS2R, AWAKE, G3S and S5 voltages must remain present on turned off machine.
If no other present, then you may have problems with the battery; test known good one.

 

[sekidata]

Hmm, I've tried two batteries and I see the same discharging behavior for both.

 

[sekidata]

Where do I look next? Charging chip? Battery current?

 

[sekidata]

Can anyone help, please?

 

[2informaticos]

Check resistance (ohm scale) over C7020/23.

 

[sekidata]

Both are around 3Ω.

 

[sekidata]

I replaced U7000, R7060, and Q7065 and the situation is unchanged.

 

[sekidata]

I also just noticed that the board does not start up when no battery is connected - I believe that's wrong for this model. Without the battery, the USB-C meter reads 20V but only 0.07A and no startup.

 

[2informaticos]

Is the battery charging?

 

[sekidata]

Yes, battery is charging fine.

 

[sekidata]

Just discovered that with only the charger connected, PPBUS is at 12.6V but the board is missing PP5V_G3S. As soon as I plug in a battery, 5V G3S appears and the machine starts up.

 

[2informaticos]

All USB-C ports have the same behavior without battery?

 

[sekidata]

Yes, both ports are the same.

 

[2informaticos]

Do you get 1V8/3V3_G3S?

 

[sekidata]

Without battery:
PP3V3_G3S = 0 with PP3V3_G3H_RTC = 3.3 and PP3V3G3S_EN = 0
PP1V8_G3S = 0 with PP1V8_SLPS2R = 1.8 and PP1V8G3S_EN = 0

 

[2informaticos]

Did you try another (original) charger?

 

[sekidata]

Yes