Common Issues and Troubleshooting Methods for Dental Chair Units

1. Suction System Malfunctions

1.1 Weak/Strong Suction Failure

Causes:

1. Incorrect pipeline connections
2. Pipe blockage by contaminants
3. Faulty microswitch (damaged spring plate or misalignment)
4. Clogged suction cup
5. Contaminated suction assembly
6. Poor water quality causing mineral deposits

Troubleshooting:

• Replace damaged components
• Inspect and repair circuits
• Clean suction valve assembly
• Recommend biweekly cup cleaning
• Use air-water syringe to flush pipes
• Maintain smooth internal passages

2. Control System Disorders

2.1 Functional Disarray

Causes:

1. Misconnected main/motor cables
2. Damaged adhesive label/controller
3. Faulty auto-reverse switch/soldering errors
4. Foot pedal failure

Solutions:

• Recheck wiring connections
• Replace damaged labels/controllers
• Test reverse switch continuity

3. Emergency Stop Failure

3.1 Non-functional Emergency Ascension

Causes:

1. Defective emergency switch
2. Incorrect switch soldering
3. Improper switch travel adjustment
4. 9-core converter wiring errors

Troubleshooting:

• Conduct switch continuity test
• Verify soldering positions per schematics
• Adjust actuator stroke to 2-3mm

4. Cold Light Malfunctions

4.1 Lighting Issues

Causes:

1. Burned-out bulb
2. Loose connectors
3. Incorrect relay wiring
4. Broken internal wires
5. Reflector detachment

Solutions:

• Replace with OEM bulbs
• Clean oxidized contacts
• Verify relay connections
• Handle reflectors carefully (soft cloth only)

5. Water Heater Abnormalities

5.1 Heating Failures/Overheating

Causes:

1. Power supply issues
2. Thermostat wiring errors
3. Failed heating element/thermostat
4. Damaged control panel
5. Relay failure
6. Temperature sensor faults

Remedies:

• Check 220V power input
• Test element resistance (normal: 30-50Ω)
• Replace malfunctioning components

6. Ultrasonic Scaler Issues

6.1 Operational Failures

Causes:

1. Power supply interruption
2. Foot pedal relay issues
3. Loose handpiece connection
4. Incorrect power settings
5. Loose control knobs
6. Solenoid valve failure

Solutions:

• Verify 24V DC power
• Tighten handpiece with wrench
• Adjust power knob clockwise
• Replace faulty valves

7. Curing Light Failures

7.1 Non-functional Curing Light

Causes:

1. Burned-out lamp
2. Oxidized contacts
3. Abnormal voltage (Verify 12V DC output)
4. Blown fuse

Troubleshooting:

• Use multimeter for continuity tests
• Clean contacts with precision knife
• Replace 2A slow-blow fuses

8. Air/Water Supply Issues

8.1 Spray System Malfunctions

Causes:

1. Pipe obstructions
2. Low air pressure (<6 kg/cm²)
3. Clogged water filter
4. Reversed water lines
5. Faulty foot control

Solutions:

• Clean/replace filters quarterly
• Verify pressure regulator function
• Check line connections (red/blue markings)

9. Pipeline Problems

9.1 Tubing Failures

Causes:

1. Aged/cracked tubing
2. Mineral deposits
3. Kinked drainage pipes
4. Leaky connections
5. Loose fittings

Maintenance:

• Replace tubing every 3 years
• Monthly chemical flushing
• Use silicone-based lubricants
• Check O-rings regularly

10. Solenoid Valve Defects

10.1 Valve Malfunctions

Causes:

1. Aged valves
2. Reversed inlet/outlet
3. Loose connections
4. Substandard quality
5. Water contamination

Solutions:

• Annual valve inspection
• Verify flow direction arrows
• Use water softeners if TDS >200ppm

11. Circuit Board Issues

11.1 Electrical Failures

Causes:

1. Short circuits
2. Moisture damage
3. Loose terminals
4. Oxidized connectors

Prevention:

• Implement moisture-proof measures
• Annual contact cleaning
• Tighten terminal screws to 0.5N·m

12. Water Bottle Defects

12.1 Reservoir Problems

Causes:

1. Faulty pressure valves
2. Non-distilled water use
3. Blocked outlets
4. Material defects

Protocols:

• Monthly autoclave cleaning
• Replace 2kg pressure valves biannually
• Use only distilled water

13. Water Source Switching Issues

13.1 Conversion Failures

Checkpoints:

1. Verify source selector position
2. Confirm main air valve status
3. Check pressure differentials
4. Inspect diaphragm integrity

Recommendation:

• Post conversion checklist near unit

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Preventive Maintenance Guidelines

To minimize operational disruptions:

1. Implement weekly function checks
2. Conduct quarterly professional maintenance
3. Maintain equipment logs (include error codes/dates)
4. Train staff on basic troubleshooting
5. Keep OEM spare parts inventory

By understanding these common failures and implementing proactive maintenance, dental practices can significantly reduce equipment downtime and ensure reliable clinical operations. Always consult manufacturer guidelines and seek professional assistance for complex electrical/mechanical repairs.