A1534 820-00244 Macbook 0v at L9000

[mon2]

The high resistance on L9000 seems to confirm the nand flash is ok. You have an enable pin so the regulator should be operational.

That is, Q9001 should be switching to dial down the high side voltage from PPBUS_G3H to the desired safe value to power the nand flash.

Confirm you have a valid voltage @ PP2V7_NAND_PVCC = should be ~5v. This voltage is after R9006.

Remove all power. Meter in resistance mode. Measure the resistance from PPBUS_G3H to L9000. If this resistance is high, the high side mosfet @ Q9001 is not defective.

Based on the above, consider to replace U9000.

[bridges_4u]

resistance from PPBUS_G3H to L9000 : 4.30 M Ohms. PP2V7_NAND_PVCC = 0v.

[mon2]

Remove all power. Measure the resistance between pins # 11 & # 12 on U9000 = 1k87 + 1k87 ohms. Confirm that the full path current sense resistance is matching the schematic values. After this confirmation, suggest to replace U9000. The suspicion is on U9000 since the enable signal remains ON yet the output is OFF. This implies that the mosfet @ Q9001 is not being driven. The dual mosfets must toggle on/off to properly dial down the PPBUS_G3H high voltage to power the nand devices.

[bridges_4u]

Yeah, Sure mon2. It looks like U9000 is partially driven by U9300 which is in turn driven by SMC and CD3215. But as we get the enable signal, I also presume that U9000 is the culprit. R9021 & R9072 are 1.87k each. Let me order u9000.