F4
Vax
User Interface / Keypad Fault
F4 displayed, no response from control buttons or touch panel
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Damaged touch panel or keypad, Loose ribbon cable between UI and PCB, Liquid ingress into control panel, Failed user interface PCB
How to Fix / Troubleshooting
Safety first: Unplug the machine before opening the control panel.
- Dry any spills: If detergent or water has been spilled on the control area, unplug immediately and allow the machine to dry for 24–48 hours in a warm, dry place before further testing.
- Inspect ribbon cable: Remove the control panel cover and locate the flat ribbon cable connecting the keypad/touch panel to the main PCB. Reseat both ends carefully.
- Check for corrosion: Look for green/white corrosion on connectors or tracks. Clean lightly with isopropyl alcohol and a soft brush.
- Test buttons: On keypad models, use a multimeter to check each button for continuity when pressed. Replace the keypad or UI board if non-responsive.
- Replace UI module: If the panel remains dead but the main PCB has power, replace the user interface PCB or touch panel assembly.
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Repair Difficulty
Hard
4/5
Required Part
User Interface PCB / Keypad
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