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Manual Reference
Welch Allyn SureTemp Plus Model 690 and 692 Thermometers Service Manual, document 80021463 Ver. A, revision date 2018-05; Welch Allyn Model 9600 Plus Calibration Tester directions for use where applicable.
Manufacturer Recommendation / AEM Status
The manufacturer recommends the following preventive maintenance for SureTemp Plus Model 690 and 692 thermometers in regular service:
- Every six months: Visually inspect the thermometer for physical damage that could cause future product failure.
- Every six months: Clean the unit according to the operator/service manual instructions.
- Every 12 months: Perform the Power-On Self Test and Model 9600 or 9600 Plus calibration testing procedure.
- Annually and whenever clinical accuracy is in question: Verify calibration.
- Extended storage: Remove the batteries. Every 12 months, reinstall the batteries and perform the Power-On Self Test and Model 9600 or 9600 Plus calibration test before use.
Manufacturer-listed service items and parts relevant to this PM include:
- SureTemp Plus Calibration Key, part number 06138-000.
- Model 9600 Plus Calibration Tester, part number 01802-110.
- Three AA 1.5 Vdc batteries. The manual lists Welch Allyn part number 53009-00 for AA alkaline batteries.
- Removable probe wells and probe/well kits appropriate for the installed oral/axillary or rectal configuration.
The manual limits field service operations to calibration verification, probe or probe-well replacement, battery replacement, and unit replacement. A unit that cannot pass the listed verification should not be adjusted beyond those field-service boundaries.
If a facility performs this PM at a different interval or changes the listed activities, that should be handled under the facility's approved AEM program, risk assessment, maintenance history, and applicable regulatory requirements.
What This PM Procedure Covers
- Device identification and configuration check.
- Six-month visual inspection and cleaning.
- Battery inspection and voltage review.
- Power-On Self Test.
- Annual Cal-Key verification.
- Annual thermometer-and-probe verification with a Model 9600 or 9600 Plus tester when used by the facility.
- Final pass/fail and return-to-service decision.
Required Tools and Equipment
- Welch Allyn SureTemp Plus Calibration Key, part number 06138-000.
- Welch Allyn Model 9600 or 9600 Plus Calibration Tester when performing the full thermometer-and-probe verification.
- Installed, functioning SureTemp Plus probe.
- Three AA 1.5 Vdc batteries if replacement is needed.
- Manufacturer-compatible cleaning/disinfection supplies.
- Appropriate personal protective equipment according to facility policy.
Step-by-Step PM Procedure
1. Confirm Device Identification and Configuration
Action: Verify the asset tag, serial number, model, probe type, probe-well color, wall holder/security configuration, and accessories. Oral/axillary probes and wells are blue; rectal probes and wells are red.
Expected outcome: The device matches the CMMS record, and the probe and probe well are the correct matching type.
2. Remove the Thermometer From Clinical Use
Action: Confirm the thermometer is not being used on a patient. Remove and discard any used probe cover according to facility policy.
Expected outcome: The thermometer is available for safe inspection, cleaning, and calibration verification.
3. Perform the Manufacturer-Listed Visual Inspection
Action: Inspect the thermometer, display, buttons, housing, probe, probe cable, probe connector, removable probe well, battery door, probe-cover storage area, and wall holder for physical damage, contamination, loose or missing parts, liquid intrusion, or conditions that could cause future failure.
Expected outcome: No damage, contamination, loose parts, or other unsafe conditions are present.
Remove from service if: The housing, probe, cable, connector, battery compartment, or other safety-related component is damaged or cannot be cleaned adequately.
4. Clean and Disinfect the Thermometer, Probe, and Probe Well
Action: Clean the thermometer and probe with an appropriate healthcare low- or intermediate-level cleaner/disinfecting wipe that uses either a 1:10 sodium hypochlorite solution or isopropyl alcohol as the active ingredient. Follow the wipe manufacturer's directions, contact time, warnings, and precautions.
Remove the probe well and disconnect the latching probe connector before cleaning the well. Clean the inner and outer probe-well surfaces with the manufacturer-listed solution, dry all surfaces thoroughly, reconnect the probe until the connector snaps into place, reinstall the well, and return the probe to the well.
Do not immerse or soak the thermometer or probe. Do not use steam, heat, gas sterilization, or an autoclave.
Expected outcome: The device is clean, dry, correctly reassembled, and free of residual contamination.
5. Inspect and Check the Batteries
Action: Inspect the battery compartment and batteries for corrosion, leakage, swelling, damage, or incorrect type. Use Biotech mode to review battery voltage when appropriate.
The manual states:
- Battery voltage is considered acceptable above 3.4 V.
- A new battery set should produce 4.5 V or more.
- The low-battery warning range is above 3.0 V and at or below 3.4 V.
- The device shuts down below 3.0 V.
Replace all three batteries together when replacement is needed. Use only AA 1.5 Vdc batteries and match the indicated polarity.
Expected outcome: Batteries and contacts are undamaged, battery voltage is acceptable, and no low-battery condition remains.
6. Perform the Power-On Self Test
Action: If needed, remove and reinstall the batteries to initiate the Power-On Self Test. Observe the display and verify that the instrument completes startup without an instrument, probe, EEPROM, or other unresolved error.
Expected outcome: The thermometer completes the Power-On Self Test and enters normal operation without an unresolved fault.
7. Perform Cal-Key Verification
Action: Remove the installed probe and connect the SureTemp Plus Cal-Key, part number 06138-000. Wait one minute for the thermometer to enter Monitor mode and display the temperature.
Pass criterion: The display reads 36.3 ±0.1 °C or 97.3 ±0.2 °F.
Remove the Cal-Key and reconnect the original probe after the check.
Expected outcome: The thermometer passes the fixed-value calibration verification.
Remove from service if: The displayed value is outside the manufacturer-listed tolerance.
8. Perform Model 9600 or 9600 Plus Thermometer-and-Probe Verification
Action: When using the Model 9600 Plus Calibration Tester, allow the thermometer and tester to remain in the same room for approximately 30 minutes before testing. Use a thermometer that passed the Cal-Key verification and a functioning probe.
Test the thermometer and probe in Monitor mode at these manufacturer-listed setpoints, beginning with the lowest temperature:
- 36.0 °C / 96.8 °F
- 38.5 °C / 101.3 °F
- 41.0 °C / 105.8 °F
Wait for the tester display to stop blinking. Clean the probe using a manufacturer-listed solution, allow it to air-dry for at least five minutes, do not apply a probe cover, and insert it fully into the Thermistor Device Port. Wait approximately one minute or until the thermometer reading remains stable for ten seconds.
Pass criterion: At each setpoint, the thermometer reading is within ±0.1 °C or ±0.2 °F of the calibration tester setpoint.
Expected outcome: The thermometer and installed probe pass all three verification points.
Remove from service if: Any setpoint is outside the manufacturer-listed tolerance.
9. Verify Normal Operation
Action: Reinstall the normal probe and probe well. Confirm the probe-removal switch initiates a measurement cycle, the display and backlight operate, buttons respond, audible indications function, and no unresolved error remains. Verify Model 692 security behavior according to the facility's configured use when applicable.
Expected outcome: Normal operating controls and indications function without an unresolved fault.
10. Complete the Return-to-Service Review
Action: Confirm that inspection, cleaning, battery review, Power-On Self Test, Cal-Key verification, and Model 9600/9600 Plus verification have passed as applicable. Confirm the probe and well are correctly matched and installed.
Expected outcome: The thermometer is ready to return to service under facility policy.
Electrical Safety Testing
The SureTemp Plus 692 thermometer is powered by three AA 1.5 Vdc batteries. The reviewed service manual does not list protective-earth resistance or touch/chassis leakage testing as part of preventive maintenance for the thermometer.
Do not add electrical-safety limits that are not applicable to this battery-powered device. Evaluate any separately powered wall holder, accessory, or calibration tester under its own manufacturer documentation and facility policy.
Pass / Fail Criteria
PM Pass Criteria
- Visual inspection passes.
- Thermometer, probe, and probe well are clean, dry, undamaged, and correctly assembled.
- Battery condition and voltage are acceptable.
- Power-On Self Test passes without an unresolved error.
- Cal-Key verification reads 36.3 ±0.1 °C or 97.3 ±0.2 °F.
- Model 9600/9600 Plus verification, when performed, passes all three setpoints within ±0.1 °C or ±0.2 °F.
- Normal controls, display, backlight, probe detection, and audible indications function.
Remove From Service Criteria
- Physical damage, liquid intrusion, corrosion, or contamination cannot be corrected.
- Probe type and probe well do not match and cannot be corrected.
- Battery condition or voltage is unacceptable and cannot be corrected.
- Power-On Self Test or normal operation produces an unresolved fault.
- Cal-Key verification is outside tolerance.
- Model 9600/9600 Plus verification fails any setpoint.
- Required controls, display, probe detection, or audible indications are unreliable.
Copy/Paste CMMS Work Order Procedure
Use the manufacturer service manual, facility policy, and approved AEM program to determine the final PM interval and return-to-service requirements.