Hi everyone.
This Mac started as "Apple logo, then shuts off", with the MagSafe light blinking orange.
After a Revive it showed the logo once and then stopped. Now there's no logo at all. It got worse gradually. No liquid damage.
Short check: no shorts found on the board. Diode readings over the whole board match a good board. Unless I missed some main areas.
Now: The board boot-loops by itself: on for ~4 s, off, repeat. Charger goes 0 → 5 V → 20 V → drops, repeat. It loops the same with the charger unplugged (battery only), and with 2 known-good batteries. Stable in DFU while installing the Software then fail and keeps cycling again.
Rails (highest value seen while it loops):
Main input
- PPBUS_AON: 11.3 to 12.4 V (never collapses)
- PPVBAT_AON: 11.38 V
Always-on (steady, don't cycle)
- PP3V8_AON: 3.8 V
- PP1V8_AON: 1.8 V
- PP1V2_AON: 1.2 V
- PP3V3_AON: 3.3 V
S2 (reach full value, then switch off with the loop)
- PP5V_S2_MAIN: 5.0 V
- PP3V3_S2: 3.3 V
- PP1V8_S2: 1.8 V
- PP1V2_S2: 1.2 V
- PP1V8_S2SW: 1.8 V
VDDH (Viper + 3 DrMOS)
- PP1V8_S1_CLVR_VDDH: 1.8 V
- All 3 phases: 1.8 V each, DrMOS supplies 5 V each, no fault or current-limit flags
SoC
- PPVDD_FABRIC_S1: 0.64 to 0.75 V
- PPVDD_FIXED_S1: 0.80 V
- PP0V81_S1_SRAM: 0.80 V
- PP0V855_S2SW_VDDCIO: 0.86 V
RAM (channel 0 / channel 1)
- VDDQ: 0.58 / 0.58 V
- VDD2H: 1.05 / 1.05 V
- AMPH: 1.12 / 1.12 V
- VDD2L: 0.95 V
- DCS: 0.86 V
PMU signals
- PMU_RESET_L: 1.22 V
- PMU_SYS_ALIVE: 1.8 V
- PMU_ACTIVE_READY: 1.22 V
- PMU_CRASH_L: 1.2 V
- PP1V8_AWAKE: 1.8 V
NAND (only the NAND0 side is populated)
- PP1V2_NAND0: 1.2 V
- PP0V9_NAND0: 0.84 V (same as a good board)
- PP2V5_NAND0: 2.5 V
- NAND0_RESET_L: 1.22 V
- PPVDD_AVEMSR_AWAKESW: 0.65 V
All values match a good board. Diode mode on the secondary rails also matches.
So every rail reaches its value, and it reaches 20 V each loop, meaning the SoC/SMC runs, then restarts. No hot spots on the thermal camera. The RAM, SoC and UA500 warm up evenly.
Revive / Restore (Configurator log, 3 attempts):
- 2 attempts: loader sent in DFU → device disconnects → never reaches Recovery
- 1 attempt: reaches Recovery → ramdisk sent → drops → never reaches RestoreOS
- Earlier: error 4042. It never gets as far as writing the NAND.
Our conclusion: power tree clean, battery excluded. The failure moves around and happens even in the first-stage loader (SoC + RAM only), so we suspect the SoC/RAM package.
Question: anything we've missed before calling it a SoC/board fault? Any known 820-02100 cause for dying in the DFU loader / Recovery stage with all rails good?
Please help.
This Mac started as "Apple logo, then shuts off", with the MagSafe light blinking orange.
After a Revive it showed the logo once and then stopped. Now there's no logo at all. It got worse gradually. No liquid damage.
Short check: no shorts found on the board. Diode readings over the whole board match a good board. Unless I missed some main areas.
Now: The board boot-loops by itself: on for ~4 s, off, repeat. Charger goes 0 → 5 V → 20 V → drops, repeat. It loops the same with the charger unplugged (battery only), and with 2 known-good batteries. Stable in DFU while installing the Software then fail and keeps cycling again.
Rails (highest value seen while it loops):
Main input
- PPBUS_AON: 11.3 to 12.4 V (never collapses)
- PPVBAT_AON: 11.38 V
Always-on (steady, don't cycle)
- PP3V8_AON: 3.8 V
- PP1V8_AON: 1.8 V
- PP1V2_AON: 1.2 V
- PP3V3_AON: 3.3 V
S2 (reach full value, then switch off with the loop)
- PP5V_S2_MAIN: 5.0 V
- PP3V3_S2: 3.3 V
- PP1V8_S2: 1.8 V
- PP1V2_S2: 1.2 V
- PP1V8_S2SW: 1.8 V
VDDH (Viper + 3 DrMOS)
- PP1V8_S1_CLVR_VDDH: 1.8 V
- All 3 phases: 1.8 V each, DrMOS supplies 5 V each, no fault or current-limit flags
SoC
- PPVDD_FABRIC_S1: 0.64 to 0.75 V
- PPVDD_FIXED_S1: 0.80 V
- PP0V81_S1_SRAM: 0.80 V
- PP0V855_S2SW_VDDCIO: 0.86 V
RAM (channel 0 / channel 1)
- VDDQ: 0.58 / 0.58 V
- VDD2H: 1.05 / 1.05 V
- AMPH: 1.12 / 1.12 V
- VDD2L: 0.95 V
- DCS: 0.86 V
PMU signals
- PMU_RESET_L: 1.22 V
- PMU_SYS_ALIVE: 1.8 V
- PMU_ACTIVE_READY: 1.22 V
- PMU_CRASH_L: 1.2 V
- PP1V8_AWAKE: 1.8 V
NAND (only the NAND0 side is populated)
- PP1V2_NAND0: 1.2 V
- PP0V9_NAND0: 0.84 V (same as a good board)
- PP2V5_NAND0: 2.5 V
- NAND0_RESET_L: 1.22 V
- PPVDD_AVEMSR_AWAKESW: 0.65 V
All values match a good board. Diode mode on the secondary rails also matches.
So every rail reaches its value, and it reaches 20 V each loop, meaning the SoC/SMC runs, then restarts. No hot spots on the thermal camera. The RAM, SoC and UA500 warm up evenly.
Revive / Restore (Configurator log, 3 attempts):
- 2 attempts: loader sent in DFU → device disconnects → never reaches Recovery
- 1 attempt: reaches Recovery → ramdisk sent → drops → never reaches RestoreOS
- Earlier: error 4042. It never gets as far as writing the NAND.
Our conclusion: power tree clean, battery excluded. The failure moves around and happens even in the first-stage loader (SoC + RAM only), so we suspect the SoC/RAM package.
Question: anything we've missed before calling it a SoC/board fault? Any known 820-02100 cause for dying in the DFU loader / Recovery stage with all rails good?
Please help.