iPhone & iPad testing

Two free tools from repair technicians: find out why an iPhone keeps restarting, and check if an iPhone or iPad has original parts.

Fixed on the bench 1/5

FixedDJI Mini 4K

Camera shaky, gimbal calibration never finishes

Fix: No hardware fault: the gimbal protector was left on at power-up. Removed it, calibrated - fully stable.

Full case on the forum soon

FixedSamsung Galaxy S24 Ultra

Liquid damage, no display at all

Fix: Cleaned the corrosion on the charge port and display connectors, repaired the display circuit, fitted a new screen.

Full case on the forum soon

FixedUSB flash drive

Stick reads only partly, most files won't open

Fix: Full read-only copy, file system rebuilt - 96 % of the files recovered.

Full case on the forum soon

Bench note

Restarts every 3 minutes? Paste the panic-full log into the analyzer - it names the missing sensor.

Bench note

'Unknown Part' after a screen or battery swap is about parts pairing, not a fault.

How it powers on

Acer Nitro 5 AN515-54 · Compal LA-H431P · measured on AC

Adapter in+330.8 ms+3VLP → EC_ON → +5VALW
Stops here: Charger LED off or no +3VLP: adapter, DC jack, or a short pulling the input down.
Power button+92.2 msON/OFFBTN# → +3VALW · +1.8VALW · +1.05ALW
Stops here: Button does nothing: the EC, the button line, or the ALW regulator's enable.
EC wakes the PCH+20 msEC_RSMRST# → PBTN_OUT#
Stops here: RSMRST# stays low: an always-on rail never reported power-good.
Sleep signals+18.96 msPM_SLP_S4# → PM_SLP_S3#
Stops here: No SLP_S4# after PBTN_OUT#: the PCH, or the BIOS chip / its firmware.
Memory rails+1.49 msSYSON → +1.2V_VDDQ · +2.5V · +1.05V_VCCST
Stops here: +1.2V_VDDQ missing: the memory regulator, or a short at the RAM.
System rails+11.84 msSUSP# → +5VS · +3VS · +1.8VS · +VCCIO
Stops here: One S rail missing: its load switch or regulator, or a short on that rail.
Power-good chain+140.7 msEC_VCCST_PG → VR_ON → PCH_PWROK → SYS_PWROK
Stops here: Stuck before SYS_PWROK: a power-good is missing - follow the chain back.
Reset + CPU core+145.1 msPLT_RST# → +VCC_CORE · +VCC_GT
Stops here: Fans spin, no picture: RAM, the BIOS image, or the display path.

PLT_RST# released - BIOS starts

MacBook Pro 13" 2016 A1706 · 820-00239

USB-C inUSB-C PDCD3215 → PPDCIN_G3H
Stops here: Charger shows nothing: the CD3215 port controller, its firmware, or the port.
Charger12.6 VISL9239 → PPBUS_G3H
Stops here: PPBUS_G3H low or 0 V: a short on PPBUS, or the ISL9239 charger.
Always-on + SMC3.3 VPP3V3_G3H → SMC
Stops here: No PP3V3_G3H: no SMC - nothing on the board can respond.
S5 railsTPS51980ASMC_PM_G2_EN → U7800 PMIC → PP5V_S5 · PP3V3_S5
Stops here: SMC alive but no S5 rails: SMC firmware or reset, or the 5 V / 3.3 V regulator.
PCH wakesbuttonS5_PWRGD → PM_RSMRST_L → PM_PWRBTN_L
Stops here: RSMRST_L stays low: an S5 rail never reported power-good.
S4 + memoryLPDDR3 1.2 VPM_SLP_S4_L → PP5V_S4 · PM_SLP_S3_L → PP1V2_S3
Stops here: Memory rail missing: its regulator, or a short at the LPDDR3.
S0 rails + CPUCPUVR_PGOODPM_SLP_S0_L → PP3V3_S0 · PPVCC_S0_CPU
Stops here: CPUVR_PGOOD missing: CPU power stages, or the CPU.
Power-goodU7800ALL_SYS_PWRGD → PM_PCH_PWROK → SYS_PWROK
Stops here: Fans spin, no picture or chime: EFI ROM, RAM, or the display path.

PLT_RST_L released - EFI boots

iPhone X · 820-00863

Lightning in5 VHydra → PP_VBUS
Stops here: No charging current: the Lightning port, its flex, or the Hydra chip.
Chargerbattery levelTigris2 SN2500 → PP_VDD_MAIN
Stops here: Takes current but stays dead: often a short on PP_VDD_MAIN.
BatteryI²CPP_BATT_VCC · fuel gauge
Stops here: Gauge not answering: random restarts - the panic log shows it.
Power key → PMUalways-on 1.8 VB2B_BUTTON → PMU · PP1V8_S2
Stops here: No reaction to the button: the PMU, its always-on rail, or the button flex.
PMU buck railsbucksPP_CPU_PCORE · PP_GPU · PP0V8_SOC_FIXED_S1
Stops here: One buck rail missing: that rail is shorted, or the PMU.
Memory + NANDLPDDR4X · NANDPP0V6_VDDQL_S1 · PP3V0_NAND · PP0V9_NAND
Stops here: Restores fail or it loops at the logo: NAND or its power.
A11 bootboot ROMSYSTEM_ALIVE · BOOT_CONFIG → DFU / iBoot
Stops here: Not even DFU mode: power to the A11, or the A11 itself.
iOS + watchdogwatchdogAP_TO_PMU_WDOG_RESET
Stops here: Restarts every ~3 minutes: the watchdog fired - a sensor is missing. Read the panic log.

iBoot hands over to iOS

Samsung Galaxy A32 5G · SM-A326B · MediaTek

USB-C in5 V / 9 VVBUS → MT6360 charger · CC1/CC2
Stops here: No charging: the port, its flex, or the MT6360.
Battery → VSYS≥ 3.5 Vbattery → VSYS system rail
Stops here: Battery under 3.5 V: charge or replace it before anything else.
Power key32 kHz to APPWRKEY → MT6359 PMIC (U5000)
Stops here: Power key does nothing: the key flex, or the main PMIC.
PMIC rails±10 %MT6359 → 1.8 V · 2.8 V · 2.2 V
Stops here: A PMIC output missing: the MT6359, or a short on that rail.
Core PMICCPU / GPUEXT_PMIC_EN → MT6315 → EXT_PMIC_PG
Stops here: No EXT_PMIC_PG: the core PMIC, or a shorted CPU / GPU rail.
Clock + AP_GOOD1.8 VOSC5000 26 MHz · AP_GOOD
Stops here: No 26 MHz or AP_GOOD low: the oscillator, or the processor.
Boot ROMUSB: BROMMT6853 BROM → preloader
Stops here: PC sees only 'MediaTek USB Port': the boot chain stopped - storage or software.
Storage → Androidlogo → lock screenUCP4000 uMCP (UFS + LPDDR4)
Stops here: Stuck at the logo: reflash first, then the uMCP (storage + RAM).

preloader hands over to Android

Real sequence from this board's schematic. Where it stops tells a technician where to measure - tap a stage.