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What This Guide Helps With
Troubleshoots intermittent temperature loss caused by probe movement, damaged cables, loose connections, batteries, probe covers, contacts, or device-side faults.
Step-by-Step Troubleshooting
1. Protect the Patient and Remove the Unreliable Thermometer From Use
Do not continue using a thermometer whose reading disappears, resets, freezes, or becomes unavailable during measurement. Provide another verified thermometer.
If dropout occurs during a clinical assessment, disregard the incomplete result.
Expected outcome: The patient is assessed with a reliable device, and the intermittent thermometer is isolated for testing.
2. Confirm the Dropout Pattern
Ask staff whether the display blanks, the temperature digits disappear, the measurement restarts, a probe error appears, or the entire device powers off. Determine whether the problem occurs when the probe, cable, thermometer, or patient moves.
Reproduce the condition without using it on a patient.
Expected outcome: The dropout is associated with a specific type of movement, stage, or displayed symptom.
3. Inspect the Probe and Cable Closely
Examine the cable from the probe tip to the connector. Look for cuts, crushing, severe bends, stretched sections, discoloration, exposed conductors, or damage near either strain relief.
Do not aggressively flex a suspect cable.
Expected outcome: The cable is intact. Any visible damage requires probe replacement.
4. Inspect and Reseat the Probe Connector
Power the thermometer off. Disconnect the probe and inspect the connector and device receptacle for debris, moisture, corrosion, bent contacts, damaged alignment features, or looseness.
Clean and dry accessible areas using approved procedures, then reconnect the probe fully.
Expected outcome: The connection is secure and the reading remains stable. If reseating resolves the dropout, proceed to repeated testing.
5. Verify Probe-Well Detection
Insert and remove the probe several times. Confirm that the thermometer consistently detects the stored and measurement-ready states.
An intermittent storage-detection fault may interrupt or reset the measurement sequence.
Expected outcome: Probe-well state changes are detected consistently.
6. Inspect the Probe Cover
Confirm that a single compatible probe cover is installed securely and does not loosen during the cycle. Replace wrinkled, damaged, contaminated, or poorly fitting covers.
Expected outcome: The probe cover remains stable and does not interrupt tissue contact or sensing.
7. Verify Battery Condition and Contacts
Install fresh, matched, correct batteries. Inspect the compartment for corrosion, weak contact pressure, residue, or a loose cover.
Observe whether the entire device resets when gently repositioned.
Expected outcome: Power remains stable during normal handling and measurement.
8. Test the Probe Cable in Normal Positions
Using an approved nonpatient test setup, allow the cable to rest in several normal positions while observing the reading. Move the cable slowly near each strain relief without excessive bending.
Stop immediately if dropout is reproduced.
Expected outcome: The reading remains stable. If dropout follows cable position, replace the probe.
9. Test With a Known-Good Compatible Probe
Install a verified compatible probe and repeat the controlled measurement and normal-position testing.
Expected outcome: The known-good probe remains stable, confirming the original probe or cable caused the dropout, or the problem remains and points toward the thermometer.
10. Compare the Suspect Probe on Another Compatible Thermometer
When appropriate, connect the suspect probe to another verified SureTemp Plus 692 and repeat the controlled test.
Follow infection-control procedures and do not use the comparison unit clinically during testing.
Expected outcome: The dropout follows the suspect probe or remains isolated to the original thermometer.
11. Check Display Stability Independently
Observe whether other display indicators flicker or disappear when the temperature drops out. A full display interruption may indicate a power or display problem rather than loss of temperature sensing alone.
Expected outcome: The dropout is classified as a probe-signal interruption, measurement reset, or complete power/display interruption.
12. Perform Repeated Functional and Accuracy Verification
Complete several approved temperature-verification cycles with the corrected or known-good components. Confirm the reading remains visible and stable throughout each cycle and that results meet approved criteria.
Expected outcome: No dropout occurs during repeated testing and temperature verification passes. If so, troubleshooting can stop.
13. Stop and Escalate an Intermittent Device-Side Fault
If the reading still drops out with a known-good probe, secure connection, fresh batteries, and stable test setup, remove the thermometer from service.
Expected outcome: The intermittent device is not returned to clinical use without qualified repair and verification.
If the Problem Persists
External causes involving the probe cable, connector, probe well, probe cover, battery contacts, and normal handling have been ruled out. The remaining problem may involve the probe receptacle, internal connection, power regulation, sensing circuitry, display circuitry, or another service-level fault.
Remove the thermometer from service, label it Out of Service, and send it for repair or bench evaluation. Use appropriate Welch Allyn service documentation and approved test equipment. Internal repairs should be performed only by qualified personnel.
Before return to service, verify stable operation through repeated cable positioning, probe insertion and removal, measurements, display observation, and approved temperature-accuracy testing. Knowing when to stop external troubleshooting is proper troubleshooting.
Clinical Use Tip
Treat any intermittent temperature dropout as an unreliable measurement, even when the reading returns; repeat the assessment with another verified thermometer.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Clinical staff reported that the SureTemp Plus 692 temperature reading disappeared whenever the probe cable was moved."
Cause
What was observed during troubleshooting.
Example:
"Clinical Engineering reproduced the dropout and found an intermittent cable near the probe strain relief."
Resolution
What action was taken.
Example:
"Clinical Engineering replaced the probe and verified stable readings through repeated cable-position tests and approved temperature verification."
Helpful Details to Include (If Known)
- Exact dropout behavior
- Measurement stage when dropout occurs
- Whether movement triggers the fault
- Probe and cable condition
- Connector and receptacle condition
- Probe-well detection
- Probe-cover condition
- Battery and contact condition
- Known-good probe result
- Comparison-device result
- Repeated verification results
- Final device status
Final Thought
Intermittent failures require controlled reproduction and careful separation of probe, connection, power, and device-side causes. Never return an unreliable thermometer to use based on a single successful cycle; verify repeatedly, escalate appropriately, and document the confirmed failure path.
That is successful troubleshooting.