Orignaliy posted by SB IT SOLUTION
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Complete Diagnosis and Troubleshooting Guide for Dell Inspiron 15-3542 (13269-1 FX3MC)
This guide includes step-by-step solutions for issues such as no power, no display, not charging, USB not working, and more.
1. No Power (Laptop Completely Dead)
Symptoms:
No response when pressing the power button.
No charging indication.
No fan movement or LED activity.
Solution Steps:
Step 1: Check DC Jack and Adapter Voltage
✅ Measure adapter voltage:
ADP_IN should be 19V.
✅ Check DC Jack Fuse (F6901):
Replace if blown.
If no 19V, check for a short circuit.
Step 2: Check Charger IC (BQ24780S)
✅ Verify ACOK signal and B+ voltage:
ACOK = 3.3V (indicates adapter detected).
B+ = 19V (when adapter is connected).
🔍 If ACOK is missing:
Inspect PQ8801/PQ8802 MOSFETs.
If B+ is missing, the charger IC may be faulty.
Step 3: Check 3.3V & 5V Regulators
✅ Verify PU4001 (TPS51225) voltage:
Should provide +3.3V_S5 and +5V_S5.
🔍 If missing, PU4001 IC may be faulty—replace it.
Step 4: Check Power Button and KBC (EC) Communication
✅ Verify PWRBTN# (Power Button) voltage:
Should be 3.3V before pressing and 0V after pressing.
🔍 If it does not drop to 0V:
KBC (NPCE285) might be faulty.
✅ Check EC/KBC power (3.3V) and reset signal.
If 3.3V is missing, PU4001 may be faulty.
2. No Display (Black Screen)
Symptoms:
Power LED turns on, but the screen remains blank.
No backlight.
External monitor works, but LCD does not.
Solution Steps:
Step 1: Check CPU & RAM Voltage
✅ Verify VCC_CORE (CPU power - ISL95813):
Expected: 0.8V – 1.2V.
✅ Check DDR3L RAM Power (TPS51716 - 1.35V):
If missing, TPS51716 may be faulty.
🔍 If CPU power is missing:
Check VR_ON, SVID_CLK, and SVID_DATA signals.
Step 2: Check BIOS and Clock Signals
✅ Reflash BIOS using an SPI programmer.
✅ Check RTC_CLK (32.768KHz) crystal:
If missing, replace the RTC crystal.
Step 3: Check GPU or Display Connection Issues
✅ Test with an external monitor:
If the external display works, LCD, eDP cable, or screen may be faulty.
✅ Verify LVDS/eDP power (3.3V_S0).
✅ Inspect Backlight Driver (PU4701 - TPS61169).
🔍 If no backlight:
Replace PU4701 or F4701 fuse.
3. Not Charging (Battery Not Charging)
Symptoms:
Laptop runs on AC power but does not charge the battery.
Displays "Plugged in, not charging".
Solution Steps:
Step 1: Check Charger IC (BQ24780S)
✅ Measure battery voltage (B+ line):
Expected: 8.4V – 12.6V.
✅ Verify ACOK and CHGR_ACIN signals:
ACOK = 3.3V, CHGR_ACIN should be low.
If missing, replace the Charger IC.
Step 2: Check Charging MOSFETs (PQ8801, PQ8802)
✅ Measure Gate voltage (G1, G2):
Should be 6V – 12V.
If missing, the MOSFET may be faulty.
🔍 If battery is not detected:
Check battery connector and SMBUS signals.
4. USB Port Not Working
Symptoms:
USB device does not work when connected.
Some USB ports work, others do not.
Solution Steps:
✅ Check USB Power (+5V_S5):
If missing, replace PU4801 (APL5606).
✅ Verify USB data lines (D+ / D-):
If missing, the USB Controller (PCH) may be faulty.
🔍 If all USB ports fail:
Reflash BIOS/KBC firmware.
5. Fan Not Running or Laptop Overheating
Symptoms:
Fan does not start.
Laptop overheats and shuts down.
Solution Steps:
✅ Verify Fan Power (5V):
Check PU5001 (Fan Driver IC).
✅ Inspect PWM & Tach signals:
PWM should be 1V – 3.3V.
🔍 If the fan is faulty:
Replace PU5001 or the fan.
6. Keyboard and Touchpad Not Working
Symptoms:
Keyboard and touchpad do not work in Windows.
Work fine in BIOS.
Solution Steps:
✅ Check +3.3V and SMBUS signals:
Ensure power from KBC (NPCE285).
✅ Verify KBC reset and clock signals:
If KBC is faulty
This guide provides a structured approach to diagnosing and fixing common issues in the Dell Inspiron 15-3542 (13269-1 FX3MC) laptop. Let me know if you need further details!
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