See the fault.
Trace the exact stage.
One technician workspace for AMOLED/OLED, IPS LCD, high-voltage backlight and touch-controller diagnosis — organized around boot order, live voltage, GR, resistance, reset and signal activity.
Exact IC pin order and timing remain model-specific; this page uses source-derived subsystem checkpoints.
Display, backlight and touch are different circuits
Start in the domain that matches the visible symptom so power and signal tests stay relevant.
AMOLED / OLED / IPS image path
Logic rails, positive/negative bias, reset, TE, MIPI DSI, FPC/EMI and panel/DDIC isolation.
BACKLIGHTLCD LED boost path
VBAT input, enable, PWM, switching stage, boost diode/coil, VLED+ and LED cathode current sinks.
TOUCHDigitizer control path
TS_VDD, TS_VDDIO, TS_RST, TS_INT, I²C/SPI, FPC/ESD and sensor-matrix isolation.
Trace the first missing rail, enable or signal
Each sequence is source-derived at subsystem level. Exact per-IC timing, pin names and delays must come from the exact datasheet or verified model profile.
| Order | Rail / Pin / Signal | Expected Voltage | When It Appears | Enable Source | GR / Diode | Scope / Logic State | If Missing / Abnormal | Next Confirmation |
|---|
Mark what is present during boot
Reference, not pin-exact datasheet data
AMOLED / OLED / IPS image diagnostics
Measurement order
Boot-time voltages / signals
Interpretation
LCD high-voltage LED boost diagnostics
Measurement order
Boot-time voltages / signals
Interpretation
What each startup checkpoint means
| Order | Point | Source Reference | Expected State | If Missing / Abnormal |
|---|
Power, reset, bus, interrupt and sensor matrix
Measurement order
Boot-time voltages / signals
Interpretation
Display + Backlight + Touch bench reference
Source-derived values are labelled as references. Exact phone-model data should replace them when a verified board-specific profile exists.
| Domain | Rail / Signal | Boot / Operating Voltage | GR / Diode | Resistance | Signal Type | Use |
|---|