Apple MacBook Pro 16-Inch 2019 - A2141 - stuck at 5V

[martyjelen]

Yes. 1.1V, stable.

[mon2]

From post #24.

P5V_3V3G3H_EN -0V
PP3V3_G3H_T -3,3V ; this voltage is enabled so the _EN signal must be a '1' (not 0v)

P3V3MAIN_PGOOD - 0V ; this should be '1' if the output voltage rail is stable

P5VG3S_EN - 0V
PP5V_G3S - 3,3V ; this voltage is enabled so the _EN signal must be a '1' (not 0v)
P5VG3S_PGOOD - 0V ; this should be '1' if the output voltage rail is stable

Confirm that you are measuring the proper pins for the 0V signals. The _PGOOD signals are open drain pins so there must be an external pull-up resistor to a pull-up power rail to park the _PGOOD lines.

[martyjelen]

I think I don't understand. Should I measure voltage or not?

[mon2]

Yes, measure the voltage to ground again of the following:

P5V_3V3G3H_EN -0V
P5VG3S_EN - 0V

That is, the above cannot be 0V since the output voltage rails are active and stable. This implies the enable signals (above) are '1' = 3v3. Confirm it.

[martyjelen]

I can confirm that P5V_3V3G3H_EN is 0V. P5VG3S_EN is also 0V.

[martyjelen]

It seems the board definitely died. Suddenly the current draw drops to zero. Now PPBUS_G3H is missing....

[mon2]

What is the voltage to ground now of ppbus_g3h?

Remove all power. What is the exact resistance in ohms to ground of this rail?

[martyjelen]

I removed both fuses. PPBUS_G3H is shorted to ground

[martyjelen]

0V 0Ω

[mon2]

Which side? Is it the isl or other downstream side that is shorted?

The cpu may be the root cause but suggest to inject 1 volt (max) onto the shorted side and hunt for the part that is heating up. Remove the heatsink off the cpu for inspection.

[martyjelen]

Pin no. 2 on both F7000 +F7001 is shorted.

[martyjelen]

C6525 was cracked. I removed it and now we are back. #45
Yesterday, 08:38 AM

[mon2]

What is the resistance to ground of the signals listed in post #45?

Very strange that the rails are enabled yet the enable lines are logic low = disable state.

[martyjelen]

P5V_3V3G3H_EN -50kΩ
P5VG3S_EN - 50kΩ

[mon2]

Measure the voltage to ground on each leg of

R7652
R7691

Voltage to ground on pin # VREG5 (pin 29) on U7650.

Voltage to ground on pin # VREG3 (pin 22) on U7650.

[martyjelen]

R7652 - 0V on both sides
R7691 - 0V on both sides

pin29 on U7650 is PP5V_S5_LDO - 2.5V
pin22 on U7650 is P5VP3V3_VREG3 - 3.3V

did you mean these ?

[mon2]

Yes. Attempt a DFU on this unit. You may have corrupt T2 firmware.

reference:
https://www.badcaps.net/forum/troubl...g3s_en-missing