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What This Guide Helps With
Troubleshoots unreadable or unstable display conditions caused by batteries, contacts, contamination, viewing conditions, physical damage, or internal display faults.
Step-by-Step Troubleshooting
1. Protect the Patient and Remove an Unreadable Device From Use
Do not use the thermometer when temperature values, units, mode indicators, or warning symbols cannot be read reliably. Provide another verified thermometer.
Inspect for cracked display windows, liquid intrusion, overheating, odor, battery leakage, or impact damage.
Expected outcome: The patient is assessed with a verified alternate device, and the affected thermometer is safely isolated.
2. Confirm the Display Symptom
Determine whether the display is completely blank, unusually dim, flickering, missing specific segments, or readable only at certain angles. Ask whether the problem occurs at startup, during measurement, or when the device is moved.
Reproduce and document the condition.
Expected outcome: The exact display failure and triggering condition are identified.
3. Verify Battery Condition
Remove and inspect the batteries. Replace the full set with fresh, matched, correct batteries and confirm proper polarity.
A weak battery set may allow partial startup while causing dimness, flicker, or unstable segments.
Expected outcome: The thermometer powers on with stable battery voltage. If the display becomes normal, proceed to final verification.
4. Inspect Battery Contacts and Compartment
Check for corrosion, residue, bent contacts, poor spring pressure, loose batteries, or a battery cover that does not secure the cells.
Clean only accessible areas using approved procedures and allow the compartment to dry fully.
Expected outcome: Battery contact is clean, secure, and stable when the device is handled normally.
5. Check Ambient Lighting and Viewing Angle
View the display under normal clinical lighting and from the expected operating position. Eliminate glare, direct sunlight, or reflections that may make a functioning display appear dim.
Compare readability with another verified SureTemp Plus 692.
Expected outcome: The display remains legible in normal use conditions. If the complaint was caused by glare or viewing angle, educate staff and document the finding.
6. Inspect the Display Window and Housing
Clean the external display window using an approved method. Inspect it for scratches, clouding, chemical damage, separation, cracks, or pressure marks.
Do not press hard on the display or use abrasive cleaners.
Expected outcome: The display window is clean and undamaged, with no external condition obscuring the information.
7. Observe the Complete Startup Display
Restart the thermometer and observe the display during startup. Note whether all expected segments briefly appear or whether the same areas remain missing.
Do not use a thermometer that omits digits or indicators needed to interpret the result safely.
Expected outcome: All necessary display segments appear clearly and remain stable. If missing segments persist, remove the device from service.
8. Check for Movement-Related Flicker
While the device is powered, gently reposition it and observe the display. Do not strike, twist, or flex the housing.
If flicker occurs with ordinary handling, suspect an unstable power contact or internal connection.
Expected outcome: The display remains stable during normal handling. Any movement-related dropout requires removal from service.
9. Verify Key Indicators During a Functional Measurement
Use an approved simulator or verification method and confirm that temperature digits, decimal point, units, mode indicators, progress symbols, and alerts remain readable throughout the cycle.
Expected outcome: All clinically necessary information remains visible from startup through completed measurement. If so, troubleshooting can stop.
10. Stop and Escalate Persistent Display Abnormalities
If fresh batteries, clean contacts, normal lighting, and an undamaged display window do not correct the problem, do not open the housing or attempt display-board repair.
Expected outcome: The thermometer is labeled Out of Service and sent for qualified evaluation.
If the Problem Persists
Common external causes involving batteries, contacts, display cleanliness, lighting, and physical obstruction have been ruled out. The remaining fault may involve the display assembly, internal connector, power regulation, control board, liquid damage, or another internal service issue.
Remove the thermometer from service, label it Out of Service, and send it for repair or bench evaluation. Use the appropriate Welch Allyn service documentation and approved test equipment. Internal repairs should be performed only by qualified personnel.
Before return to service, verify the complete startup display, stable operation during movement, all temperature digits and indicators, repeated measurements, and temperature accuracy. Knowing when to stop external troubleshooting is proper troubleshooting.
Clinical Use Tip
A missing decimal point, unit symbol, or digit segment can cause a clinically significant misreading even when the displayed number appears plausible.
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 display flickered and became difficult to read during temperature measurements."
Cause
What was observed during troubleshooting.
Example:
"Clinical Engineering found corrosion on one battery contact causing intermittent power to the display."
Resolution
What action was taken.
Example:
"Clinical Engineering cleaned the accessible battery contact, installed fresh matched batteries, and verified a stable complete display during repeated measurements."
Helpful Details to Include (If Known)
- Blank, dim, flickering, or missing-segment condition
- When the display problem occurs
- Battery condition and replacement result
- Battery contact condition
- Display window condition
- Lighting and viewing-angle findings
- Startup segment behavior
- Movement-related behavior
- Functional test result
- Final device status
Final Thought
An unreadable display is a patient-safety failure. Rule out batteries, contacts, glare, contamination, and external damage first, then remove the thermometer from service when required information remains unstable or incomplete. Verify and document the full display before return to use.
That is successful troubleshooting.