PP3V3_G3H missing due to a short circuit on the rail itself (refer to symptoms for repairing short to ground on PP3V3_G3H below).PP3V3_G3H missing due to a short circuit on the input to PP3V3_G3H creation circuit.The LDO will only appear when the charger is plugged into the corresponding port so to find out which one is bad, plug in the charger one port at a time and measure 1v1 LDO_BMC of corresponding chip. It can also be caused by a bad CD3215 which is missing its 1v1 LDO. If 5 V and 0.00 A draw, most likely a 0–1 Ω short to ground on PP3V3_G3H.The PP3V3_G3H power IC is smart enough, usually, when it detects a straight 0 Ω short, to just turn off. When PP3V3_G3H is directly shorted to ground, it won't produce heat. PP3V3_G3H is most likely shorted to ground with a 0–1 Ω short, most likely due to bad capacitor. Board not fixed.Ĭharger at 5 V, 0.000 A draw (no power draw) Visual inspection of shorted component shows solder ball popping out the side of component.On this board this situation is always a no-fix. If those measure under 1 Ω (0.3–0.8Ω) then you most likely have a direct 12 V short to CPU/GPU. Measure PPBUS_G3H to vCORE coils (coils around CPU/GPU). Inject 1 V (increase if no reaction), watch for hot spots with thermal camera. Can be caused by a tiny speck of conductive material in the battery connector.Ĭan also be caused by C7605 shorted on PP5V_S4. On USB-C models, it actually results in the machine not turning on at all. On older MacBooks, this would result in no battery recognition and a lower voltage on PPBUS_G3H. Replaced trackpad cable and system is now reliably booting again.Ĭheck for low resistance to ground on SMBUS_SMC_5_G3H_SDA or SMBUS_SMC_5_G3H_SCL. It leaves that as STORAGE_LB_EN and goes to U9300 as its EN line.
This goes to R5650 and then to R8901 as PP3V3_S4 and leaves as STORAGE_EN to go to J9600 lifeboat connector. I had one with a damaged trackpad cable that had shorted PP3V3_S4_TPAD.I ran a jumper wire from pin 1 C9400 (PPVIN_2V7NAND_LB) and conformal coated that enameled jumper wire and considered it a viable repair. After inspection and not finding any breaks in that PPVIN_2V7NAND_LB line, I deliberated on where to best access PPVIN_2V7NAND_LB from. Looking at the schematic that PPVIN_2V7NAND_LB line comes from PPBUS_GSH so as a test I ran a jumper from the closest source of PPBUS_GSH (pin 1 C6582) to the testpad and the SSD was now detected. However there was no continuity between that TP and pin 43 (PPVIN_2V7NAND_LB) of J9600. I had previously checked the integrity of the Lifeboat connector at J9600 and all was good there. I had one case where no damage in the R9350 area but upon checking, there was no PPVIN_2V7NAND_LB at the TP above R9350.In one case, a short circuit caused by C9416/Q9401/U9400 due to U9400 circuit failure.When not liquid damaged, often a dead SSD (you're screwed).If it is shorted, replace the Piccolo chip (inject 1.3 V on these inductors usually won't give you a strong hotspot). Probe inductors near the Piccolo chip.