I need help with this, please.
MacBook Air A2681- 820-02536
I got this MacBook from a customer which is not turning on; it has no display. It's stuck on 5V
Does not recognize in DFU mode.
No signs of liquid.
These are the readings.
MacBook Air A2681- 820-02536
I got this MacBook from a customer which is not turning on; it has no display. It's stuck on 5V
Does not recognize in DFU mode.
No signs of liquid.
These are the readings.
MacBook Air A2681 / 820-02536 — Measurements Summary
Symptom
- Stuck at 5 V
- 11-second cycling pattern
- Additional 4-second sub-cycle observed on PP0V88_S1
- Battery not connected (charger only)
- DFU mode: no detection
- PP1V05_S2SW_VDD2H at 0.050 V confirmed normal against good board reading of 0.043 V
Live Power Rail Measurements (charger connected)
| Rail | Reading | Behaviour |
|---|---|---|
| PPBUS_AON | 12 V → 12.3 V → 12 V | Cycling every 11 s |
| PP5V_S2 | 5.19 V | Cycling every 11 s |
| PP3V3_S2 | 3.29 V | Cycling every 11 s |
| PP3V3_AON | 3.3 V | Cycling every 11 s |
| P5VS2_PWR_EN | 1.8 V | Cycling |
| PP0V88_S1 | 0 V → 0.80 V | Cycling every 4 s |
| PP0V779_S1_SRAM | 0.78 V | Present for a couple of seconds |
| PP1V25_AWAKE_IO | 1.25 V | Present for a couple of seconds |
| PP2V58_AWAKE_NAND_VCC | 2.59 V | Present for a couple of seconds |
| PP0V88_S1 | 0 V | Never comes up (initial measurement) |
| SOC_XTAL24M_IN | 0.58 V | Steady |
U5700 Pin Readings
| Pin | Signal | Voltage |
|---|---|---|
| 8 | PP3V8_AON | 3.8 V |
| 7 | PP5V_AON | 5 V |
| 5 | P3V8AON_PVCC | 5.19 V |
| 12 | P3V8AON_PWR_EN_R | 4.79 V |
U5200 Pin Readings
| Signal | Voltage |
|---|---|
| P_IN | 5.1 V |
| AUX_DET | 0.84 V |
| SMC_RST_IN | 0 V |
| VDDA | 4.79 V |
| VDDP | 4.79 V |
| EN_MVR | 4.79 V |
| AUX_OK | 1.76 V |
| A_MON | 0 V |
| B_MON | 0 V |
PMU LDO Output Readings
| Rail | Voltage |
|---|---|
| PP1V8_AON_MPMU | 1.8 V |
| PP1V2_AON_MPMU | 1.2 V |
| PP1V8_AON_SPMU | 1.8 V |
| PP1V2_AON_SPMU | 1.2 V |
Diode Mode Readings.
| Net | Reading | Note |
|---|---|---|
| PP5V_S2 | 0.311 | Normal |
| PP3V3_S2 | 0.485 | Normal |
| PP1V8_S2 | 0.258 | Normal |
| PP1V25_S2 | 0.216 | Normal |
| PP0V855_S2SW_CIO | 0.251 | Normal |
| PP1V05_S2SW_VDD2H | 0.050 | Normal |
| PP0V88_S1 | 0.340 | Normal |
| BUCK12_FB (at R77C0) | 0.330 | Normal |
IR Camera Observations
During the 11-second cycle:- U5340: heating/glowing
- RC622, RC623, RC624, RC625, RC626, RC627 (All connected to PP5V_S2 power line all glowing momentarily) Diode mode readings on these components are correct
- UF400 slightly warmer than UF500 and other CD3217s
