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What This Guide Helps With
Troubleshoots unresponsive controls caused by contamination, stuck buttons, battery instability, operating state, damaged keypad surfaces, or internal control faults.
Step-by-Step Troubleshooting
1. Protect the Patient and Remove the Device From Active Use
Do not attempt to troubleshoot unresponsive controls while the thermometer is being used for patient care. Provide another verified thermometer.
If the device cannot be turned off normally, remove the batteries only after the patient is disconnected and the thermometer is out of clinical use.
Expected outcome: Patient care continues without relying on a thermometer whose controls cannot be operated reliably.
2. Confirm Which Controls Are Affected
Ask staff whether one button, the mode button, or the entire keypad is unresponsive. Determine whether the issue occurs only during a particular screen, measurement stage, or after cleaning.
Reproduce the condition and document whether any audible, visual, or display response occurs.
Expected outcome: The affected control and operating state are identified.
3. Verify the Thermometer Is in the Correct Operating State
Return the probe to the well, allow any active measurement cycle to end, and restart the thermometer. Some controls may not respond during certain device states.
Do not repeatedly press multiple keys rapidly.
Expected outcome: The thermometer reaches its normal ready or standby state and accepts control input. If normal operation returns, perform repeated functional testing.
4. Inspect the Keypad Surface
Examine the keypad for dried contamination, adhesive residue, a wrinkled or lifted overlay, cracks, punctures, chemical damage, or signs of liquid intrusion.
Clean the surface using an approved method and allow it to dry fully. Do not flood the keypad or use sharp objects.
Expected outcome: The keypad is clean, dry, intact, and free of anything that could restrict button movement or contact.
5. Check for a Physically Stuck Button
Press each external control individually with normal force. Determine whether one button feels continuously depressed, fails to return, or has a different tactile response from the others.
Do not pry at the keypad or attempt to lift the overlay.
Expected outcome: Each control returns normally after being pressed. A physically damaged or stuck keypad requires removal from service.
6. Verify Battery Condition and Contacts
Install fresh, matched, correct batteries and inspect the compartment for corrosion, poor contact, or looseness. Unstable power can cause frozen or inconsistent keypad response.
Restart the thermometer after battery replacement.
Expected outcome: The thermometer powers normally and responds consistently to controls. If battery correction resolves the issue, proceed to final verification.
7. Test Each Button Separately
Operate one button at a time and allow the display to respond. Verify the power control, mode selection, timer or recall functions, and any other available front-panel controls appropriate to the device configuration.
Expected outcome: Every required control produces the expected visible response. If all controls operate repeatedly, troubleshooting can stop after measurement verification.
8. Check for Probe or Probe-Well State Conflicts
Confirm that the probe is recognized and that the probe well correctly detects storage and removal. A storage-detection problem may make the device appear unresponsive because it is not entering the expected control state.
Expected outcome: The probe and well state change normally. If correcting the storage condition restores keypad function, complete final testing.
9. Compare Behavior With a Verified Device
Compare the sequence and response time with another SureTemp Plus 692 configured for the same department. This helps distinguish a normal control limitation from an actual failure.
Do not change protected configuration settings simply to make the devices match.
Expected outcome: The suspect device responds like the verified comparison unit or is confirmed abnormal.
10. Perform Final Functional Verification
Complete repeated startup, mode-selection, probe-removal, and approved temperature-verification cycles. Confirm every required button works before, during, and after measurement as intended.
Expected outcome: The keypad and mode button respond consistently throughout normal operation. If so, the device may be returned to service.
11. Stop and Escalate an Unresponsive Keypad
If one or more controls remain unresponsive after cleaning, restarting, checking power, and confirming the correct operating state, remove the thermometer from service.
Expected outcome: The device is not returned to use with an intermittent or nonfunctional control interface.
If the Problem Persists
External contamination, button obstruction, battery instability, probe state, and normal operating-state causes have been ruled out. The remaining fault may involve the keypad membrane, keypad connection, control circuitry, liquid damage, or another internal failure.
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 completed only by qualified personnel.
Before return to service, verify all controls, mode selection, startup and shutdown, probe detection, repeated temperature measurements, and accuracy. Knowing when to stop external troubleshooting is proper troubleshooting.
Clinical Use Tip
Do not return a thermometer to patient care when a button works only intermittently; inconsistent mode selection can produce a valid-looking result in the wrong measurement mode.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Clinical staff reported that the mode button on the SureTemp Plus 692 did not respond."
Cause
What was observed during troubleshooting.
Example:
"Clinical Engineering found dried disinfectant residue around the edge of the mode button that restricted normal operation."
Resolution
What action was taken.
Example:
"Clinical Engineering cleaned and dried the keypad surface and verified repeated mode changes and successful temperature measurements."
Helpful Details to Include (If Known)
- Specific button or controls affected
- Whether the problem is constant or intermittent
- Keypad appearance and tactile response
- Recent cleaning or spill history
- Battery and contact condition
- Probe and probe-well detection
- Comparison-device findings
- Number of successful button cycles
- Final temperature-verification result
- Final device status
Final Thought
Start with patient safety, operating state, cleanliness, and stable power before assuming keypad failure. Confirm every required control repeatedly, remove intermittent devices from service, and document the actual cause and return-to-service testing clearly.
That is successful troubleshooting.