Apple Logic Board · Level 3

MacBook Pro A1502 —
Level 3 Repair Guide

✦By Joe · Board-level repair technician
◈ Schematic available2 files — PDF & BoardView
Boards: 820-3476 (2013/2014) & 820-4924 (2015) CPU: Intel Haswell / Broadwell MagSafe 2 — 65W 16 video sources analysed

Overview & model comparison

The MacBook Pro 13" Retina A1502 comes in two major logic board revisions. Although the chassis is identical, the electrical and mechanical differences are significant for diagnostics.

Characteristic 820-3476 2013/2014 820-4924 2015
CPU Intel Haswell (4th generation) Intel Broadwell (5th generation)
Trackpad Mechanical (physical click) Taptic Engine / Force Touch (haptic)
Trackpad / battery cable routing Passes under the battery Passes over the battery
Fan behaviour Always ON in S0 state On demand (CPU temperature)
BIOS chip Large format Small format
SMC transferable Yes (3476 ↔ 3476 only) No (reprogramming required for 3476→4924)
PPBUS_G3H nominal 12.58V 12.58V
Field identification: Machine off → press trackpad. 820-3476 = real mechanical click. 820-4924 = rigid surface, no tactile return. If the battery is swollen, the 2013/14 trackpad may also feel stiff — inspect visually.
2015 fan behaviour: On the 820-4924, the fan does NOT spin automatically at startup. This is not a fault symptom. It only activates when the CPU heats up.
PPBUS = 12.58V on MacBook Pro A1502. Do not confuse with MacBook Air where PPBUS is 8.4–8.6V. Any reading of ~8.5V on PPBUS_G3H of an A1502 indicates a problem.

Voltage rails — complete reference

Main rails of the A1502 with nominal values, measurement points and diode-mode resistance values.

Rail Nominal value Required state Measurement point Resistance → GND Source / Notes
PPDC_IN G3H ~18–20 V Adapter plugged in R7020 pin1 O.L. Raw MagSafe 2 input. 65W = 18–20V depending on load.
PP3V42_G3H G3H 3.42 V Always present (adapter or battery) L7095 / C7200 ~O.L. Generated by U7190 (ISL9240). First rail to check. Absent = no charger LED.
PPBUS_G3H G3H 12.58 V Always present when G3H active R7005 / F7140 ~95–320 kΩ Generated by U7100 (ISL6259). Source of all secondary rails.
PPVRTC_G3H G3H 3.3 V Always present C1910 / U1900 ~O.L. RTC clock. Absent = CPU never boots despite PPBUS OK.
PPVBAT G3H 7.6–8.4 V Battery connected Q7451 / C7451 — 3-cell Li-Po. New battery ~8.2V. Critical threshold <6.8V.
PP5V_S5 S5 5.0 V S5 state (soft-off) L_PP5V_S5 ~12 kΩ Buck from PPBUS_G3H. Enabled by SMC via PM_SLP_S5_L.
PP3V3_S5 S5 3.3 V S5 state L_PP3V3_S5 ~2 kΩ Buck from PPBUS_G3H. Absent = SMC stuck, no startup possible.
PP3V3_S5_AVREF_SMC S5 3.3 V S5 state C5021 (near SMC) ~O.L. SMC voltage reference. Corrosion on C5021/C5020 = very common fault.
PP3V3_S4 S4 3.3 V S4 state U2030 (logic gate, 820-4924) ~O.L. On 820-4924: U2030 internal short can block S0. Test by removing it.
PP5V_S3 S3 5.0 V S3 state and higher L7520 output / IO board connector <1Ω if shorted! Powers the IO board (USB, HDMI, SD). Short circuit common on IO board.
PP3V3_S3 S3 3.3 V S3 state IO cable connector ~O.L. Persistent short after IO board disconnected → likely PCH fault.
PP_CPU_VCORE S0 0.8–1.8 V variable S0 state L_VCORE — Dynamic CPU core voltage (IMVP8). Varies with load.

Power tree

MagSafe 2 65W / Battery (PPVBAT or PPDC_IN)
↳U7190 ISL9240 → PP3V42_G3H (3.42V) via R7121/R7122 feedback
↳D7010 (HA) + Q7010 (P-ch) → charger path switching → U7100 ISL6259
↳U7100 ISL6259 → PPBUS_G3H (12.58V)
↳Buck → PP5V_S5 + PP3V3_S5 + PP3V3_S5_AVREF_SMC
↳Buck → PP5V_S3 (IO board) + PP3V3_S3
↳Buck → PP3V3_S4 → U2030 (820-4924)
↳VR CPU → PP_CPU_VCORE (IMVP8 dynamic)
↳PP3V42_G3H → U1900 RTC → PPVRTC_G3H (3.3V)

Key components

Reference Part Function Rails managed Common failure mode
U7100 ISL6259 (QFN-28) Battery charger + main PMIC PPBUS_G3H (12.58V) Shorted → PPBUS absent. Inject 5V on PPBUS → U7100 heats up.
U7190 ISL9240 (regulator) Generates PP3V42_G3H from PPDC_IN PP3V42_G3H Corroded R7121/R7122 (feedback 10kΩ) → PP3V42 absent. 820-3476 fault.
Q7010 P-channel MOSFET Charger path switch. Gate driven by D7010. PPDC_IN → PPBUS_G3H src Rarely fails alone. D7010 typically fails first.
D7010 Zener diode "HA" (SOD-323) Regulates Q7010 gate voltage to turn it on. Classic Rossmann fault. Q7010 gate Open circuit → gate = source → Q7010 blocked → no PPBUS, no green LED.
F7005 DC-IN fuse PPDC_IN line protection PPDC_IN 18V before fuse, 0V after → blown. Rare. Check adapter before replacing.
U1900 RTC clock (SOT-23/TSOP) Generates PPVRTC_G3H (25 MHz + 32 kHz). Without it, CPU never boots. PPVRTC_G3H Corroded C1910 (fragile pad!) → PPVRTC absent → no boot despite PPBUS OK.
SMC System Management Controller (BGA) Orchestrates boot sequence, manages fan, battery, LEDs All control Not transferable 820-3476 ↔ 820-4924 without reprogramming.
C5021 / C5020 0402 capacitors (near SMC) PP3V3_S5_AVREF_SMC voltage reference PP3V3_S5_AVREF_SMC Corrosion → short circuit → PP3V3_S5 pulled down → no power. Very common fault.
U2030 Logic gate SC-70 (820-4924 only) PP3V3_S4 rail. Not required at boot under normal conditions. PP3V3_S4 Internal short → blocks S0. Test: remove U2030, if machine boots = confirmed cause.
TI2557 (IO board) USB Power Switch (IO board) USB regulator on IO board PP5V_S3 (IO board) Bypass capacitor (~43µF/6.3V) shorted → blocks PP5V_S3 on the whole board.
PCH / CPU Intel PCH (integrated in CPU die) Platform Controller Hub — same die as CPU PP3V3_S3, PP5V_S3 Persistent PP3V3_S3 short → inject 3V → CPU heats = dead PCH. Unrepairable without reball.

Boot sequence G3 → S0

The sequence is orchestrated by the SMC. Each step is conditioned on validation of the previous one (PGOOD signal or equivalent).

# Signal / Rail Value Condition If absent
1 PPDC_IN 18–20 V MagSafe adapter plugged in Check charger, connector J7000, fuse F7005
2 PP3V42_G3H 3.42 V U7190 active from PPDC_IN ISL9240 fault or corroded R7121/R7122 (820-3476)
3 PPBUS_G3H 12.58 V ISL6259 (U7100) active, D7010 OK D7010 (HA) failed, ISL6259 shorted, or fuse blown
4 PPVRTC_G3H 3.3 V PP3V42_G3H → RTC clock (U1900) Corroded C1910 / lifted pad → no boot possible
5 PP5V_S5 + PP3V3_S5 5V + 3.3V SMC initialised, PM_SLP_S5_L command C5021/C5020 short circuit, or stuck SMC
6 Power button → SMC_ONOFF_L pulse low PP3V3_S5_AVREF_SMC present Check PP3V3_S5_AVREF_SMC (C5021)
7 PP5V_S3 + PP3V3_S3 5V + 3.3V SMC activates S3 switches IO board short circuit, or faulty PCH
8 Fan (820-3476) Spinning S0 state reached Machine stuck in S3 or S5 — S0 never reached
9 PP_CPU_VCORE ~1.0V (VID) PCH validates → activates VR CPU Faulty PCH, or PP1V05_S0 absent
10 POST / startup — All S0 rails OK, RAM initialised Check RAM rails (PP1V35_S0, PP0V6_S3)

Interactive diagnostic tool

Enter the measurements taken on each rail. The system calculates probable causes based on rail interdependencies as defined in the 820-3476 and 820-4924 schematics.

Always measure out of circuit (resistance to ground) before reconnecting to detect short circuits. If resistance < 5 Ω on a power rail, locate the short before applying power.
Measurements taken — click OK / NOK / NR (Not Recorded) for each rail
Enter at least a few rail measurements then click Analyse.

Documented faults

16 videos analysed. 10 scenarios ranked by frequency and difficulty.

#001 Short circuit C5021 / C5020 — PP3V3_S5_AVREF_SMC SMC zone, often isolated corrosion
FrequentEasy
▼
Symptoms

Charger → green LED then nothing. No startup, no fan spin. Very low AC draw (~130 mA). Sometimes immediate shutdown on power attempt.

Schematic location

C5021 and C5020 on the PP3V3_S5_AVREF_SMC line, directly adjacent to the SMC. 0402 decoupling capacitors for SMC voltage reference.

Procedure
  1. Measure PP3V3_S5 in continuity mode: beep → short circuit confirmed
  2. Visually locate C5021 (component side, near SMC)
  3. Microscope inspection: corrosion sometimes isolated to this single capacitor
  4. Remove C5021 (iron at 350°C or hot air with flux)
  5. Re-measure resistance PP3V3_S5 → GND: must return to >500 Ω
  6. Replace with 0402 capacitor of same value (donor board or stock)
  7. Inject 3.3V on the line, verify no heat spots
Corrosion can be very localised (a single capacitor) with no visible liquid trace to the naked eye. Always inspect under microscope even on "clean" boards.
Sources

GeofzYn7Jt8 (Rosmarky) · Q2kBPlEG4gM (Maccare) · mO3rmCtMOoc (Saqib Engineer)

#002 RTC zone corrosion — C1910 / U1900 / PPVRTC_G3H absent Lifted pad, broken trace
FrequentMedium
▼
Symptoms

Green charger LED, PPBUS_G3H present (12.58V), PP3V42 present, but machine does not start. No fan spin (820-3476). PPVRTC_G3H absent or unstable.

Schematic location

RTC clock zone: U1900 (clock IC), C1910 and C1905 associated. Progressive corrosion from ambient humidity or old liquid damage.

Procedure
  1. Inspect U1900/C1910 zone under microscope: visible corrosion?
  2. Measure PPVRTC_G3H on C1910: must be 3.3V
  3. Check trace continuity C1910 pin1 → U1900: if broken, jumper wire required
  4. Remove C1910 carefully (pad is very fragile!)
  5. If pad lifted: scrape lacquer to expose trace, create solder bridge
  6. Replace C1910 (1µF / 6.3V) and U1905 if corroded
  7. If U1900 damaged: remove, clean, replace from donor board
  8. Test: fan should spin (820-3476)
WARNING C1910 pad: Pin 1 pad is very fragile. Work in steps with fine wick + IPA. If pad is lifted and trace intact: create a thick solder bridge to the nearest accessible via.
Sources

DltTyDG2MNk (Reset Lab — RTC region) · YU_kUp35drQ (Paul Daniels #262)

#003 PP5V_S3 short on IO board — failed USB capacitor ~43µF/6.3V capacitor near HDMI/USB port
FrequentEasy
▼
Symptoms

Machine boots without IO board connected but not with it. Pulsing current draw ~20–30 mA. PP5V_S3 short detected on IO board connector (resistance <1Ω).

Schematic location

IO board (left daughter board). Decoupling capacitor (~43µF/6.3V) upstream of the TI 2557 USB regulator, near the HDMI/USB port. Not referenced in board view — identify visually.

Procedure
  1. Disconnect IO board cable, re-measure PP5V_S3 on mainboard
  2. If resistance normal → IO board short confirmed
  3. Inject 1V / 2A on PP5V_S3 of IO board + thermal camera or IPA method
  4. Identify heating capacitor (usually the one closest to HDMI port)
  5. Remove 2–3 suspect capacitors (~43µF) with hot air at 380°C
  6. Test each removed capacitor: the bad one will beep (continuity)
  7. Replace only the faulty one
  8. Re-test: machine must boot with IO board reconnected
If a 43µF/6.3V capacitor is unavailable, it is acceptable to leave out the USB bypass capacitors (role: inrush reservoir). The machine will work without them.
Sources

kCjH9Pe23hQ (Adamant IT) · uJjQBDP3s8I (Reset Lab — short 5V line)

#004 Blown fuse F7005 (DC-IN fuse open) 18V before, 0V after fuse
RareEasy
▼
Symptoms

No LED on charger, current draw ~6 mA. Voltage present at fuse input (~18V), absent at output. No short circuit detected on main rails.

Procedure
  1. Check 18V on F7005 pin1 (charger side)
  2. Check 0V on F7005 pin2 → blown fuse confirmed
  3. Measure rail resistances BEFORE replacing (look for root cause)
  4. If no short circuit: bridge with appropriate gauge wire (or SMD fuse)
  5. Check D7010 and ISL6259 as likely underlying cause
A blown fuse with no obvious short circuit may indicate a faulty adapter or transient overvoltage. Test with another charger before concluding.
Sources

pofavtBTT8M (Louis Rossmann) · xZkcdI6ye8Q (Electronics Repair School)

#005 Corroded R7121/R7122 — PPBUS_G3H absent (820-3476) ISL9240 feedback resistors corroded
MediumMedium3476 only
▼
Symptoms

Green charger LED, but PPBUS_G3H absent (measures ~0.16V). No short on PPBUS. Corrosion visible under microscope around U7190. R7121 and R7122 (10kΩ) damaged.

Procedure
  1. Measure PPBUS_G3H on F7140: if absent, trace back to U7190
  2. Check trace continuity around U7190 using board view
  3. Remove corroded R7121 and R7122 (10kΩ)
  4. Measure continuity of associated traces
  5. Replace R7121/R7122 with new 10kΩ 0402 or from donor board
  6. Replace C7121/C7122 (0.1µF/25V) if corroded
  7. Test: PPBUS_G3H should return to 12.58V
Typical fault on machines used in humid environments (tropical regions, condensation). Sulfate corrosion on ISL9240 feedback resistors.
Sources

YKhuorXIE24 (Level 3 Microsoldering)

#006 Corroded U2030 — PP3V3_S4 shorted to GND (820-4924) Logic gate not required at boot, but blocks S0 if shorted
Rare (4924)Medium4924 only
▼
Symptoms

PPBUS present, PP3V42 present, but machine does not start. Corrosion visible on U2030 (AND/OR logic gate). Without U2030 removed, machine boots.

Test procedure
  1. Identify U2030 on the 820-4924 board view
  2. Visual inspection under microscope: corrosion on pins?
  3. Remove U2030 (hot air at 355°C)
  4. If machine boots without U2030 → U2030 is the cause (PP3V3_S4 short)
  5. Replace U2030 from donor board
U2030 is NOT required at boot under normal conditions. Removing it is therefore a non-destructive diagnostic test.
Sources

nTqVc6qWRb8 (Reset Lab — 820-4924)

#007 Failed D7010 (HA) diode — PPBUS absent, no green light Classic Rossmann fault — Q7010 gate not driven
CommonEasy
▼
Symptoms

Current draw ~6 mA, no charger LED, no PPBUS. Fuse F7005 intact. 18V present on Q7010 source (C7012 pin1) but gate = source → MOSFET blocked open.

Procedure
  1. Verify 18V on R7020 pin1
  2. Measure C7012 pin1 (Q7010 source) and pin2 (gate):
    — If identical → D7010 dead (open circuit)
  3. Locate D7010 (marking "HA") on board view
  4. Test D7010 in diode mode: should show a forward voltage drop
  5. If open: replace D7010 (Zener diode SOD-323)
Fault identifiable quickly with a single measurement on C7012. Simple repair (SOD-323 component).
Sources

pofavtBTT8M (Louis Rossmann)

#008 Short circuit PP3V3_S3 / PP5V_S3 — dead PCH Unrepairable without full CPU/PCH reball
MediumCritical
▼
Symptoms

Persistent short on PP3V3_S3 or PP5V_S3 after removing all suspect capacitors and disconnecting IO board. Injecting voltage on the rail → CPU/PCH heats strongly.

Confirmation procedure
  1. Rule out all other causes: IO board, mainboard capacitors, U2030, U6201 (audio)
  2. Inject 3V / 1A on PP3V3_S3 with thermal camera or IPA method
  3. If CPU/PCH die heats → dead PCH internally
  4. CPU and PCH are on the same die → replacing PCH alone is impossible
  5. Solution: donor board with a different, repairable fault
Dead PCH = dead CPU. No standard A1502 stencil available in most shops. Cost-effective solution: find a donor board with a different fault (corrosion, fuse) and repair that instead.
Sources

lj7DFAecEm0 (Reset Lab — PCH confirmation)

#009 Shorted ISL6259 (U7100) — PPBUS absent, PMIC heats up Main PMIC shorted or dead
MediumMedium
▼
Symptoms

PPDC_IN present (18V), PP3V42 present (charger LED OK). Inject 5V on PPBUS rail → ISL6259 (U7100) heats. PPBUS absent or incorrect.

Procedure
  1. Inject 5V on PPBUS with thermal camera or IPA alcohol
  2. Identify heating component: if U7100 → PMIC faulty
  3. Measure sensing resistances on ISL6259
  4. Remove U7100 with hot air at 380°C, reball, replace from donor board
  5. Test PP3V42 and PPBUS after replacement
Sources

xZkcdI6ye8Q (Electronics Repair School — ISL6259 shorted)

#010 Multiple corrosion — jumper wires, component replacement Extensive liquid damage, broken traces
VariableAdvanced
▼
Symptoms

Multiple corroded components in a zone. Interrupted traces. After IPA cleaning, some pads lifted or traces broken.

Procedure
  1. Clean with IPA/ultrasound, dry completely
  2. Inspect all traces under microscope in the corroded zone
  3. Verify continuity on each trace before soldering
  4. If pad lifted with intact trace: create solder bridge
  5. If broken trace: jumper with 36–38AWG wire to via identified in board view
  6. Only jumper if resistor value is known. For capacitors: verify value and polarity.
Never jumper a capacitor without knowing its value and polarity. A direct GND↔rail bridge on a decoupling capacitor = permanent short circuit.
Sources

NdxpcdllHB0 (Rosmarky) · pUKgKCFhNh8 (Paul Daniels #257)

Tools & equipment

Measurement
Multimeter
DC V, Ω, diode, continuity modes (Fluke 115 or BM235)
Measurement
Bench power supply
0–20V / 0–3A, mA display (Korad KA3005D or equiv.)
Measurement
Thermal camera
FLIR or Seek Thermal, resolution ≥80×60
Measurement
USB Power Meter
Real-time current display on MagSafe line
Soldering
Hot air station
350–400°C adjustable, controlled airflow (UYUE, Quick)
Soldering
Soldering station
Fine tip, 320–360°C
Soldering
Desoldering wick
1.5–2mm, integrated flux (Chemtronics TechSpray)
Optics
Trinocular microscope
7–45x, long WD objective, HDMI camera (AmScope SM-4TP)
Software
Flex / ZXW BoardView
.brd files for 820-3476 and 820-4924
Software
Schematic PDFs
820-3476_SCH.pdf / 820-4924_SCH.pdf
Consumables
NC solder flux
No-clean, SMD syringe
Consumables
IPA 99%
Corrosion cleaning + hot spot detection method
Mechanical
Pentalobe P5 screwdriver
Bottom case screws
Mechanical
Torx T5 screwdriver
Internal logic board screws
Method
IPA method (short circuit location)
Inject current on shorted rail + IPA drops → evaporation marks the hot component

BGA & SMD soldering techniques

Component Package Hot air Heat duration Reball Notes
ISL6259 (U7100) QFN / TSSOP 28 pins 380°C, moderate flux 45–60s No (re-tin pads) Lift with tweezers, check pads. Source: donor board.
U1900 (RTC) SOT-23 / TSOP 8 pins 360°C 20–30s No Flux, fine tweezers. Exposed pins.
U2030 (820-4924) SC-70 / SOT-363 6 pins 350–360°C 15–20s No Extra-fine tweezers. Remove for test before replacing.
SMC BGA ~160 balls Preheat 150°C, peak 230°C Full profile Yes (stencil required, SAC305 0.3mm) Transferable 3476↔3476 only. Reprogramming required for 4924.
CPU/PCH (single die) BGA 1300+ balls Preheat 180°C, peak 235–240°C Long profile Yes (large stencil, SAC305 0.4mm) ⚠ Not recommended in standard workshop. Prefer donor board.
0402 capacitors SMD 0402 350°C, low airflow 10–15s — Heated tweezers for maximum precision. Check polarity (tantalum/electrolytic).
IPA method for localisation: Apply 3V/0.5A on the shorted rail. Drop 2–3 drops of 99% IPA on the suspect zone. IPA evaporates instantly above the heating component → precise identification without a thermal camera.
BGA fracture after impact: On A1502 boards that have suffered a drop, the CPU can have fractured balls without an immediate short circuit. A reflow may temporarily restore the connection. Inform the customer of possible recurrence.

Video sources (16 videos)

YouTube ID Title / Channel Board Fault covered
GeofzYn7Jt8Short PP3V3_S5_AVREF_SMC — Rosmarky820-3476Corroded C5021, SMC capacitor replacement
mO3rmCtMOocA1502 No Power — Saqib Engineer—Capacitor short near SMC, injection + IPA method
uJjQBDP3s8IShort on 5V line — Reset Lab820-4924PP5V_S3 short IO board, USB TI2557 capacitor
YKhuorXIE24Green light no power — Level 3 Microsoldering820-3476PPBUS absent, corroded R7121/R7122 around ISL9240
92ArANk4474No Green Light — Laptop Repairs820-4924No green light, replaced SMC reset IC
YU_kUp35drQ#262 No Turn On — Paul Daniels820-3476Corroded C1910, C1910+U1905 replacement, RTC restore
Q2kBPlEG4gMNo Power Issue Solved — Maccare—Corroded C5020, R7xxx, U5560, multiple components replaced
pUKgKCFhNh8#257 Green Light No Power — Paul Daniels820-3476U7203 zone corrosion, 3V/5V controller replacement
lj7DFAecEm0No Power Repairs — Reset Lab820-4924PP3V3_S3 short, U6201 audio suspect, injection → PCH heat
nTqVc6qWRb8No Power (820-4924) — Reset Lab820-4924Corroded U2030 → PP3V3_S4 short, logic gate replacement
fjtwMsA1owoNo Power Repair — Saqib Engineer—Power supply zone capacitor repair
DltTyDG2MNkNo Power RTC Region — Reset Lab820-3476C1910 pad lifted, RTC corrosion, pad bridge + U1905 replacement
xZkcdI6ye8Q820-4924 Logic Board Repair — Electronics Repair School820-4924Blown F7005 + shorted ISL6259 (U7100), double repair
kCjH9Pe23hQNo Power Diagnostics LFC#396 — Adamant IT820-4924PP5V_S3 shorted IO board, secondary rails method
NdxpcdllHB0Liquid Damaged — Rosmarky—Charger zone corrosion, desoldered resistor, jumper, cleaning
pofavtBTT8MSimple A1502 Repair — Louis Rossmann820-4924DC-IN fuse only, D7010 HA, Q7010/D7010/C7012 explanation
Related Symptom Hubs
→No Power →No Charging →No Display / No Backlight
Related Repair Guides
→ MacBook Air A1466