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| How To Repair Samsung Galaxy Z Fold 4 Fake Charing | |
|---|---|
| Device | Galaxy Z Fold 4 5g |
| Affects part(s) | Motherboard |
| Needs equipment | Hot Air Station, Soldering Iron, Tweezers, Donor board/New IC, Flux, Soldering Wick |
| Difficulty | ◉◉◉◉ Specialist |
| Type | Soldering |
Problem description
Samsung Z Fold 4 displays the charging animation but never boots. Acts as if charging but battery percentage does not increase.
Symptoms
- Shows charging symbol only
- Stays stuck on charging logo
- Battery percentage does not increase
- Phone does not power on normally
- V_VAT line measuring 0 Ω (dead short)
Solution
The failure is caused by a short on the V_BATT power rail, usually due to a failed ASL01 power IC.
Removing the IC clears the short; replacing it resolves fake charging permanently.
Diagnostic Steps
1. Visual Inspection
- Check the mainboard for corrosion or burn marks.
- Inspect USB-C daughterboard, battery connector, and PMIC areas.
- Ensure no aftermarket battery is causing brownout behavior.
2. Diode Mode – V_BATT Rail Check
- Probe the V_BATT test point / capacitor bank near the FPC connectors.
- Expected normal reading: typically in the hundreds of kΩ or >1MΩ.
- Faulty board reading : 0.09 Ω → confirmed short.
3. Short Hunting
- Use multimeter continuity across the V_BATT line.
- Use thermal cam or voltage injection (1 V, limited to 1–2 A).
- In this case, no component heated visibly during first injection.
- Move to boardview/diagram → V_BATT rail maps to ASL01 Charging IC (Located right next to the Battery Connector FPC).
4. Confirm Shorted IC
- Apply rosin + re-inject voltage.
- ASL01 IC heats up → confirmed bad component.
Repair Steps
1. Remove the Faulty ASL01 IC
- Mask surrounding components with high temperature tape.
- Apply hot air.
- Gently lift the ASL01 IC.
2. Re-Test the V_VAT Rail
- Measure at same point as initial short.
- After IC removal: reading becomes 19 MΩ.
- This confirms the short is fully cleared.
3. Install New ASL01 IC
- Clean pads with solder wick + flux.
- Apply fresh leaded solder.
- Reball or use pre-balled IC.
- Align and solder the new ASL01 Charging IC.
4. Final Measurement
- After reinstallation, check V_BATT again:
- Reading becomes 2.16 kΩ / .469V (normal range from reference).
5. Assemble & Boot Test
- Reconnect battery and screen.
- Phone now boots normally and charges correctly.