What Are The Common Faults Of Ultrasonic Cleaning Generators?

1. No response upon power-up; power indicator light is off
• Symptoms: No activity from the unit when powered on; fans do not spin, and the screen does not light up.
• Causes: Missing external power supply; damaged power cord or power switch; blown input fuse; earth leakage protection tripped.
• Key Note: If the fuse blows immediately upon power-up, do not repeatedly replace it; the rectifier bridge is likely broken down, a power transistor is short-circuited, or there is a short circuit on the transducer side pulling down the load.

 

2. Indicator light is on and fans spin, but there is no ultrasonic output (unit fails to oscillate)
• Symptoms: Panel is powered and frequency is displayed, but the tank shows no vibration or cavitation bubbles.
• Causes:
◦ Transducer terminals are loose, oxidized, or disconnected; output cable is short-circuited.
◦ Driver board or oscillation circuit failure; no excitation signal output.
◦ Power transistor or SCR damaged; power circuit is open.
◦ Automatic frequency tracking failure; unable to lock onto the transducer's resonant point.
• Troubleshooting: Disconnect the transducer output lines and test if the generator oscillates under no-load conditions to distinguish between a main unit fault and a transducer fault.

 

3. Alarm upon startup, overload protection triggered, or frequent tripping
• Symptoms: Overload/overcurrent alarm triggers a few seconds after startup, causing automatic shutdown; circuit breaker trips.
• Causes:
◦ Transducer insulation degradation, leakage, or cracked piezoelectric elements (most common).
◦ Impedance mismatch between generator and transducer; load current exceeds limits.
◦ Power transistor aging (increased internal resistance); poor heat dissipation triggering overheat protection.
◦ Liquid level too low or dry startup (running without liquid easily burns out the transducer and triggers generator protection).

 

4. Weak power, poor cleaning performance, and low current
• Symptoms: Unit oscillates and creates surface ripples, but cavitation is weak and cleaning is ineffective; operating current is below the rated value.
• Causes:
◦ Frequency drift; deviation from the transducer's resonant frequency (e.g., 28kHz/40kHz); impedance mismatch.
◦ Aging of power components; reduced output capability.
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Transducer aging, debonding, or damage to some vibrators (resulting in lighter load and decreased current)
◦ Poor heat dissipation; high temperatures causing automatic power derating
◦ Low or highly fluctuating supply voltage

 

5. Frequency drift, unstable frequency tracking, and inconsistent output intensity
• Symptoms: Intermittent ultrasonic output; fluctuating current readings; fault worsens as temperature rises
• Causes:
◦ Thermal drift or aging of components (capacitors, resistors, etc.) on the mainboard
◦ Transducer temperature changes causing resonant point shifts that exceed the automatic frequency tracking range
◦ Poor contact in output wiring, leading to continuous load impedance fluctuations
• Consequences: Prolonged operation in an off-resonance state accelerates damage to power transistors and transducers

 

6. Excessive generator heating
• Symptoms: Casing becomes hot to the touch; unit shuts down due to overheating protection after a short period
• Causes: Cooling fan jammed or clogged with dust; prolonged full-load operation; poor impedance matching causing high reactive power loss; excessively high ambient temperature

 

7. Abnormal noise (internal generator noise)
• Symptoms: Buzzing or humming sounds inside the main unit, accompanied by current fluctuations
• Causes: Loose transformer core or high-voltage arcing; dust accumulation or moisture on the circuit board; abnormal operation of power components