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What This Guide Helps With
Troubleshooting weak ultrasonic cleaning or a Sonics Low indication caused by loading, solution, degassing, basket, or bath-condition issues.
Step-by-Step Troubleshooting
1. Ensure Patient and Processing Safety First
Remove the ultrasonic cleaner from instrument-processing use when Sonics Low is displayed or cavitation performance is questionable.
Do not release instruments for clinical use based on a cleaning cycle performed in a unit with unverified ultrasonic performance. Follow facility procedure for affected instrument loads, including reprocessing when indicated.
Avoid reaching into the tank or handling contaminated sharps unnecessarily. Use appropriate PPE and safe instrument-handling practices.
Expected outcome: Potentially ineffective pre-cleaning does not contribute to reuse of inadequately processed instruments.
Why it matters: Ultrasonic cleaning supports removal of debris before subsequent reprocessing steps. Poor cavitation may reduce cleaning effectiveness.
2. Confirm the Reported Condition
Power the unit on and confirm whether the display indicates Sonics Low or whether staff are reporting poor cleaning results without a displayed fault.
Document whether the issue occurs:
- Immediately when a cycle starts
- Only with instruments loaded
- Only after extended operation
- With every load or intermittently
- During a foil-performance test or routine cleaning observation
Expected outcome: The reported fault or reduced-performance condition is confirmed before further troubleshooting.
Why it matters: Midmark identifies Sonics Low as a sonics-feedback condition that may occur when the tank is overloaded; persistent faults can require service evaluation.
3. Verify Power and Basic Operating Condition
Inspect the power cord, rear power-switch area, and outlet connection for looseness, damage, heat discoloration, or liquid exposure.
Confirm the rear power switch illuminates and that the unit completes normal startup without additional faults.
When appropriate, verify the outlet with a known-working device or approved outlet tester according to department policy.
Expected outcome: The unit has stable power and no external electrical condition is contributing to abnormal performance.
If the issue resolves: Return the unit only after confirming normal cavitation performance and documenting the correction.
4. Check Tank Fill Level and Cleaning Solution
With the unit not processing instruments, confirm that fluid reaches the required liquid-level sensor without exceeding the maximum fill level.
Confirm that the correct cleaning agent and concentration are being used according to the solution and instrument manufacturers’ instructions. Replace visibly contaminated, heavily soiled, or incorrectly mixed solution.
Use water temperature appropriate for the cleaning agent; Midmark states that cleaning efficacy can only be guaranteed when bath temperature is at least 70°F / 21°C, and water above 122°F / 50°C should not be placed into the tank.
Expected outcome: The tank contains correctly prepared cleaning solution at an appropriate fill level and temperature.
Why it matters: Low, contaminated, incorrectly mixed, or improperly conditioned solution can appear as poor cleaning performance even when the ultrasonic system is operating.
5. Run a Degas Cycle With No Instruments Loaded
Remove all instruments from the tank. Confirm correct liquid level and solution concentration, place the lid on the unit, and run a degas cycle.
Allow the degas cycle to continue until visible bubbles have risen from the solution; Midmark recommends a degas period of 5 to 10 minutes. End the degas cycle manually when complete.
Expected outcome: Trapped air is removed from freshly prepared or recently disturbed solution before cavitation performance is evaluated.
If the issue resolves: Document that performance improved after proper degassing and return the unit only after satisfactory verification.
6. Evaluate Loading and Basket Use
Confirm that instruments are placed in the approved basket and are not resting directly on the tank bottom.
Remove excessive instrument mass, tightly nested trays, stacked cassettes, or unusually heavy loads. Run a reduced-load cycle if the fault occurred only while heavily loaded.
Inspect the basket feet for worn or missing protective coating. If metal is visible through worn basket-foot coating, remove that basket from use because it can damage the tank.
Expected outcome: The cleaner operates with an appropriate suspended load and without basket-related tank contact.
Why it matters: Midmark lists excessive tank loading as an external cause of Sonics Low and instructs that items should be suspended in the basket rather than placed on the tank bottom.
7. Inspect the Bath and Exterior Condition
Turn the unit off, disconnect power, and allow the tub to cool before inspection or cleaning.
Drain the bath as appropriate and inspect the tank for:
- Heavy residue or contamination
- Visible pitting, erosion, cracks, or leakage
- Foreign objects contacting the tank
- Damage caused by a worn basket
- Unusual heat, odor, or sound during prior operation
Clean the empty tub only with a damp, soapy, nonabrasive cloth and rinse as appropriate.
Expected outcome: The tank and basket are clean and free from visible damage that could affect performance or safe use.
Why it matters: Midmark states that contaminated liquid and tank-contacting debris may reduce bath efficacy and contribute to tank wear or leakage.
8. Perform a Cavitation Performance Check
After correcting fill level, solution, degassing, loading, and tank-condition concerns, perform a foil test according to facility procedure and applicable local requirements.
Use fresh, correctly mixed solution and an unloaded basket/tank configuration appropriate for the test. Compare the result with department acceptance criteria or previous documented results when available.
Expected outcome: The foil test demonstrates consistent cavitation activity across the expected cleaning area.
If the issue resolves: Record the acceptable foil-test result and return the device to service according to department policy.
Why it matters: Midmark identifies foil testing as a method used to evaluate ultrasonic-cleaner efficiency and recommends testing when deterioration in performance is suspected.
9. Stop Troubleshooting if Sonics Low or Weak Performance Continues
If the unit continues to display Sonics Low, repeatedly fails a cavitation-performance check, produces abnormal sound or heat, or has visible tank damage after external causes have been addressed, discontinue further operational troubleshooting.
Do not open the unit or attempt internal ultrasonic generator, transducer, or base-plate repairs as part of this guide.
Expected outcome: A persistent sonics fault is escalated safely rather than allowing unreliable cleaning performance to continue.
If the Problem Persists
Once power, solution condition, fluid level, degassing, loading, basket condition, tank condition, and cavitation performance have been checked, common external causes have been ruled out.
Persistent Sonics Low or failed cavitation performance is likely to require internal service evaluation of the ultrasonic-generation system or related components. Midmark’s service troubleshooting information identifies internal generator/base-plate conditions among possible causes after overload has been ruled out.
The device should be:
- Removed from service
- Labeled Out of Service
- Sent for repair or bench evaluation by qualified service personnel
Knowing when to stop and escalate is proper troubleshooting, especially when inadequate ultrasonic cleaning may affect instrument-processing reliability.
Clinical Use Tip
Do not evaluate cleaning performance using instruments intended for immediate patient care. Remove the cleaner from workflow first, notify the processing area as appropriate, and verify performance safely with an approved test method before returning it to use.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Staff reported the Midmark QuickClean ultrasonic cleaner displayed Sonics Low and instruments appeared inadequately cleaned after the cycle."
Cause
What was observed during troubleshooting.
Example:
"Unit produced a repeated Sonics Low indication after confirming proper fill level, fresh cleaning solution, completed degas cycle, reduced basket load, and failed foil-performance verification."
Resolution
What action was taken.
Example:
"Removed ultrasonic cleaner from service, labeled it Out of Service, documented failed cavitation verification, and routed the unit for bench evaluation of the ultrasonic-generation system."
Helpful Details to Include, If Known
- Outlet and power cord condition checked
- Displayed message confirmed as Sonics Low
- Fluid level at required sensor level
- Solution replaced or concentration verified
- Bath temperature checked
- Degas cycle completed
- Instrument load reduced or removed
- Basket feet inspected for exposed metal
- Tank inspected for residue, pitting, or leakage
- Abnormal heat, odor, or sound observed
- Foil-test result documented
- Final device status: returned to service or removed for repair
Final Thought
Ultrasonic-cleaner troubleshooting should begin with safe instrument-processing practices and simple external causes: solution, level, degassing, loading, basket condition, and tank cleanliness. When performance remains unreliable after verification, removal from service and accurate CCR documentation protect both patients and the reprocessing workflow.
That is successful troubleshooting.