SureTemp Model 986 Service Manual Rev B

Contents 1.

General Information ... 1 1.1 About the Model 986... 1 1.1.1 System Block Diagram... 1 1.2 Technical Support... 1 1.3 Safety Warnings and Notices ... 2 1.4 Classifications... 2 1.5 About this Manual ... 3 1.5.1 Related Documents... 3 1.6 Return Procedure ... 3 1.7 Terms used in this Manual ... 4

2.

Service ... 5 2.1 Basic Operation of the Model 986 ... 5 2.1.1 2.1.2 2.1.3 2.1.4 2.1.5 2.1.6 2.1.7

Types of units... 5 Major Thermometer Components... 6 Instrument Reset ... 6 POST (Power Up Self-Test)... 7 Probe Type Test ... 7 Operational Checks... 8 Default algorithm for oral and axillary modes (blue probe)... 11

2.2 Service Procedures... 11 2.2.1 2.2.2 2.2.3 2.2.4 2.2.5

List of Tools and Equipment ... 11 Preventative maintenance ... 12 Cleaning and Sterilization ... 13 Service Activities... 14 Component Replacement... 14

2.3 Battery Removal and Replacement... 15 2.3.1 Battery Life... 15 2.4 Calibration Procedures ... 16 2.4.1 2.4.2 2.4.3 2.4.4 3.

Calibration Limits Table ... 16 Water Bath procedure ... 16 Variable Temperature Water Bath procedure... 16 Model 9600 Calibration procedure... 17

Troubleshooting ... 19 3.1 Error Codes ... 19 3.1.1 Types of Errors ... 20 3.1.2 Error Recall Mode ... 21 3.2 Troubleshooting Table ... 22 3.3 Disassembly/Reassembly... 24 3.4 Field Serviceable Parts ... 24 3.4.1 Main Components... 24 3.4.2 Model 986 PCA ... 26

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3.4.3 Replacement Parts for PCA ... 27 Appendix A.

Theory of Operation... 29

A.1 Overview ... 29 A.1.1 A.1.2 A.1.3 A.1.4 A.1.5 A.1.6 A.1.7 A.1.8

Temperature Probes ... 30 Probe Switch... 30 Normal Mode Description... 30 Power Supply ... 31 Microcontroller... 31 Reset/Self Tests ... 31 Microprocessor Clock... 32 Temperature Measurement And Display ... 32

A.2 Temperature Measurement A/D Converter... 32 A.2.1 A.2.2 A.2.3 A.2.4 A.2.5 A.2.6

Use of Analog Circuitry ... 32 A/D Theory of Operation ... 32 Circuit Description... 33 Probe Type Detection... 34 Instrument ID Logic ... 34 Circuit Operation... 34

A.3 Probe warming (Oral probes only) ... 35 A.3.1 A.3.2 A.3.3 A.3.4 A.3.5 A.3.6

Theory of Operation... 35 Circuit Operation... 35 Liquid Crystal Display... 36 Probe Switch... 36 Mode Button... 36 Horn ... 37

Appendix B.

Specifications... 39

Appendix C.

Limited Warranty... 41

Appendix D.

Wiring Diagram ... 43

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List of Figures Figure 1: System Block Diagram ... 1 Figure 2: Model 986 Thermometer... 5 Figure 3: M986 Display ... 7 Figure 4: Peak Monitor Mode... 9 Figure 5: Battery Removal and Replacement ... 15 Figure 6: Thermometer Assembly ... 24 Figure 7: Printed Circuit Assembly... 26 Figure 8: System Block Diagram ... 29 Figure 9: Schematic Diagram ... 43

List of Tables Table 1: Self-Test Error Table... 20 Table 2: Main Components... 25 Table 3: Replacement Parts for PCA ... 27 Table 4: Configuration Truth Table ... 34

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1. General Information 1.1

About the Model 986 The Welch Allyn Model 986 SureTemp is a portable, predictive thermometer that accurately measures body temperatures in a few seconds at oral, axillary, or rectal sites. Oral/axillary and rectal probes utilize single use disposable probe covers to help limit cross-contamination. This instrument was developed for use by medical professionals and day care providers. The predictive technology allows the user to take oral temperatures in approximately four seconds, axillary temperatures in approximately 10 seconds (for children under four years), and rectal temperatures in approximately 15 seconds.

1.1.1 System Block Diagram Model 986 PCA Configuration

NEC UPD 789407 uP A/D Converter Circuit

16 Bit Timer

Voltage Reference Circuit

Serial I/O

CPU

8 Bit A/D

LCD Driver

Serial Port

Mode Button

Horn Driver

Battery Detector Circuit

Horn

Probe Warmer Circuit

Liquid Crystal Display

Probe Configuration Jumpers

Four Conductor Coil Cord

Thermistor

2 AAA Batteries

Probe Warmer

Probe Assembly

Figure 1: System Block Diagram

1.2

Technical Support Contact Welch Allyn Customer Service at: Welch Allyn, Inc 7420 Carroll Road San Diego, CA 92121

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800-535-6663

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1. General Information

1.3

Safety Warnings and Notices 1. DO NOT USE THIS INSTRUMENT IN THE PRESENCE OF FLAMMABLE ANESTHETICS. 2. Do not use this instrument for any purpose other than those specified in the User’s Guide. Doing so will invalidate the instrument’s warranty. 3. Oral/Axillary SureTemp thermometer models (with a blue ejection button at the top of the probe) are to be used for taking oral and axillary temperatures only. Rectal models (red ejection button) are to be used for taking rectal temperatures only. Use of a probe at the wrong type of site will result in temperature errors. 4. Use only single-use Welch Allyn disposable probe covers. The use of any other probe cover or the failure to use a probe cover may produce temperature measurement errors and increase the chances for cross-contamination. 5. The thermometer case is not waterproof. Do not immerse it in liquids or drip fluids onto it. 6. Dispose of batteries in accordance with all local, state and federal environmental guidelines. 7. This instrument consists of high quality precision parts and should be protected from severe impact and shock. Do not use the thermometer if you notice any signs of damage to the probe or instrument. Contact Welch Allyn Customer Service at (800) 535-6663 for immediate assistance. Note: This thermometer complies with current required standards for electromagnetic interference and should not present a problem to other equipment or be affected by other devices. As a precaution, avoid using this device in close proximity to other equipment.

1.4

Classifications Type of protection against Internally Powered Equipment electric shock Degree of protection against Type BF Applied Part electric shock Degree of protection against Ordinary (IPXO) ingress of liquids Degree of safety in the Equipment not suitable for use presence of flammable with flammable anesthetics anesthetics Mode of operation Continuous

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1.5

About this Manual This manual describes both the Model 986 Oral/Axillary and Rectal thermometers. Most topics and procedures are equally applicable to both products. Where there are differences, we will note which instrument is being discussed.

1.5.1 Related Documents End user operation of the Model 986 is covered in the M986 User Guide and Quick Reference Guide. Model 986 User Guide

70994-1000

Model 986 Quick Reference Guide

71019-0000

This Service Manual assumes that the technician understands these operations.

1.6

Return Procedure Contact Welch Allyn Customer Service at (800) 535-6663 before returning an M986 Thermometer to the factory for service.

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1.7

Terms used in this Manual The following abbreviations are used in this manual: Main Component Terms PCB

Printed circuit board (the board itself)

PCA

Printed circuit assembly (with all components)

LCD

Liquid Crystal Display

BATT.

Battery.

DMM

Digital Multi-Meter

O-Scope

Oscilloscope

Component Reference Terms

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C

Capacitor

D

Diode

E

Test point

J

Connector jack

L

Inductor

LS1

Horn

P

Connector plug

Q

Transistor

R

Resistor

S

Switch

U

Integrated circuit

X

Crystal, resonator

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2. Service 2.1

Basic Operation of the Model 986 The Model 986 is a portable digital thermometer. Service technicians should check the basic operation of the instrument before it is disassembled.

1 Probe cover ejection button 2 Probe cover box 3 Probe storage channel

4 LCD display

5 Mode button

6 Battery Compartment

Figure 2: Model 986 Thermometer

2.1.1 Types of units The M986 is available from the factory in the following configurations: •

Oral /Axillary or Rectal Probe

•

° F/°C, ° F Only, °C Only

Note: Thermometer configuration cannot be modified in the field.

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2.1.2 Major Thermometer Components Batteries

The Model 986 thermometer uses two standard disposable alkaline AAA cells. These batteries provide long life for reduced down time. No battery charging is required or possible.

Probe

Two types of probes are available: Oral/Axillary (blue), and Rectal (red). The probe is not detachable and is connected to the printed circuit board at the factory.

Probe Covers

The probe covers are unchanged from previous models and are compatible across all of Welch Allyn’s thermistor-based thermometers. Note: The use of probe covers other than Welch Allyn PN 05031 is not allowed, and will affect the accuracy of the instrument.

2.1.3 Instrument Reset If a problem is reported with an instrument, please check its operation before resetting it. Reset Procedure 1. Remove the batteries from the instrument (see page 15). 2. After battery removal, any remaining charge due to internal capacitance must be discharged to achieve a proper reset. After the batteries are removed, press the Mode button for about five seconds. The electronics will now properly reset when the batteries are replaced. 3. Reinstall the batteries. Watch the display and observe the power up self-test (page 7).

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2.1.4 POST (Power Up Self-Test) The self-test includes a series of internal microprocessor self tests, instrument electronics tests, and the display test. If there are internal electronics problems detected by the self-tests, the Err (error) icon will be displayed and an audible tone will sound. Refer to the Error Codes table in the Troubleshooting section (page 19) for an explanation of any error code. The M986 electronics are tested each time the batteries are replaced. •

The Power up test begins with all display segments and icons simultaneously illuminated, followed by a display of the software revision in this instrument. The M986 beeper also briefly sounds at the beginning of the test.

Figure 3: M986 Display •

At the end of the test, the display goes blank and the unit is ready to operate.

If there is no display, any missing segments, or no beeper, refer to the Troubleshooting table (page 22).

2.1.5 Probe Type Test Test the probe to make sure that the correct type of probe is attached to the unit. With the probe shaft in the probe well and the display blank, press the Mode button for three seconds. After three seconds, the instrument will beep and the display shows the icon with the measuring site blinking. •

For a blue (oral/axillary) probe, either the head or arm should blink, depending on whether the instrument is configured for Oral or Axillary measurements.

•

With a red (rectal) probe, the leg icon should blink.

If the wrong icon is blinking, there is a problem with either the probe or the probe type configuration in the instrument. 1. Refer to the mode table on the schematic diagram (Appendix D). 2. In the mode table, locate the type of instrument – oral only, rectal only, etc. that you are using. 3. Open the thermometer and locate the jumpers. Verify that the jumpers are configured for your type of unit. 4. If the jumpers are not configured properly, contact Welch Allyn Customer service for assistance.

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2.1.6 Operational Checks Normal Mode Normal mode operation is the rapid mode of temperature taking. This is the default mode and is automatically selected when the probe is withdrawn from the probe well. 1. When the probe is withdrawn from its storage well, every segment on the display will be illuminated. Watch for the display to change from the all segments test to the body icon display. 2. When the unit is ready, it will beep. The °F or °C symbol (whichever is selected) will illuminate, and the measuring site (oral, axillary, rectal) will begin to blink. 3. Load the probe cover at this time. The instrument is now ready for the probe to be placed in the measuring site. Note: It is possible that the display will switch from the measuring site display to the “walking segments” display and back again several times before the probe is inserted in the site. This is acceptable operation and will not adversely affect the temperature taken. Monitor Mode The thermometer will automatically switch to Monitor Mode under certain conditions: •

If the instrument determines that room temperature is above 33.9°C (93.0°F).

•

If the thermometer is unable to predict a temperature, after 15 seconds for Oral/Axillary and 30 seconds for rectal, due to improper technique such as excessive probe movement at any patient site (i.e. mouth, rectum, axillary).

Note: The thermometer reads the probe temperature immediately upon removal from the storage well. If the probe was just replaced from a previous temperature and immediately extracted, insufficient time may have passed to allow the probe to cool to room temperature. This will cause the instrument to determine room temperature to be higher than actual. The instrument will switch to Monitor mode immediately if it detects room temperature to be above 33.9 °C (93.0°F). For best results, the user should wait at least 30 seconds between Normal mode temperature measurements. If Monitor mode does not display expected temperatures, refer to the Troubleshooting table on page 22.

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Temperature Display With correct use, the patient’s temperature will be displayed in about four seconds in oral mode, about 10 seconds in axillary mode, and about 15 seconds with a rectal probe. The instrument will beep to signal completion of the Normal Mode temperature cycle. Automatic Shutoff If the probe is left out of the storage well after completion of a Normal mode temperature, the unit will shut off automatically after 10 seconds to conserve power. Simply replace the probe in the storage well to prepare for the next temperature. The instrument will shut off automatically if the probe temperature remains below 28.9°C (84.0°F) for more than 30 seconds. Peak Monitor Mode Peak Monitor mode allows long term monitoring of a patient’s peak temperature. Unlike predictive mode, Peak Monitor mode will follow a temperature as it rises and display this temperature until the probe detects a higher temperature. When this occurs, the higher temperature is displayed. Peak Monitor mode provides a direct readout of the peak probe temperature. The instrument can set in Peak Monitor mode by immediately pressing the Mode button for two seconds after a predictive (normal) temperature has been taken. Constant Temperature

Flashing Body icon disappears

Figure 4: Peak Monitor Mode Peak Monitor mode will be indicated on the display by a continuous temperature reading with a blinking ° F or ° C Icon at the upper right corner of the LCD, and by the body icon disappearing.

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The typical slow rise in temperature when Peak Monitor mode is used is due mainly to the mouth temperature slowly recovering from placement of the colder (room temperature) probe. The probe itself is actually very fast at rising to the temperature of its surroundings, usually reaching it within a few seconds. Because of this slow mouth recovery, three minutes is the recommended time to wait before recording a Peak Monitor mode temperature. Peak Monitor mode is also useful in testing the accuracy of the thermometer when the probe can be warmed to a known temperature, as with a Welch Allyn Model 9600 Calibration Tester or in a water bath (see section 2.4). In Peak Monitor mode, after approximately 60 seconds of no increase in temperature, the ° C / ° F icon stops flashing. You will hear two triple beep sounds, and the peak temperature will be displayed on the LCD. Note: If the unit is left in Peak Monitor Mode for a total of five minutes, it will automatically shut off to conserve power. If Peak Monitor mode does not display expected temperatures, refer to the Troubleshooting table on page 22. °F / °C Conversion When a final temperature is displayed (in Normal, Recall, or Monitor mode), press and release the Mode button to toggle the temperature between °F/°C. Note: A recalled temperature will be displayed in whichever scale (°F/°C) is selected at the time of recall. This setting can be changed during display. If pressing the Mode button does not change the scale of the displayed temperature, refer to Mode Button Problems in the Troubleshooting table on page 22. Temperature Recall With the instrument in low-power mode (sleep mode or blank display), press and release the Mode button to cause the most recent measured temperature to be displayed for five seconds. The stored temperature value appears with a °F or °C symbol (whichever is selected) and an M indicating it is from memory. •

If the recalled temperature was a normal mode temperature, the flashing symbol of the measurement site is also displayed.

•

If the recalled temperature was a Peak Monitor temperature, only the temperature is displayed, with no site indicated.

Activation of the probe well switch (place the probe in the well) will interrupt the temperature recall function.

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Temperature recall problems If the last temperature cannot be recalled, refer to Temperature Recall Problems in the Troubleshooting table on page 22. If pressing the Mode button does not change the scale of the displayed temperature, refer to Mode Button problems in the Troubleshooting table.

2.1.7 Default algorithm for oral and axillary modes (blue probe) Two predictive algorithms are available: oral and axillary. To change the default algorithm: 1. Place the unit in low power mode. 2. Press and hold the Mode button for at least two seconds, until a short beep is heard. The current algorithm will be displayed. 3. To advance to the next algorithm, press the Mode button momentarily. Note: When replacing the batteries, the default power up setting is the oral predictive algorithm.

2.2

Service Procedures 2.2.1 List of Tools and Equipment Most service operations can be performed with standard tools and test meters:

Model 986 Thermometer

•

A #1 Phillips screwdriver can be used for all instrument screws.

•

A standard lab 3.5 digit digital multi-meter (DMM) will provide sufficient accuracy for most tests. A needle-tipped pair of probes is recommended. An oscilloscope is sometimes the only way to analyze high speed signals, but is not generally required.

•

Standard electronics tools and supplies for small surfacemounted and through-hole component rework will be needed to perform any electronics repairs. Some surface-mounted components are extremely small and present a challenge for rework by hand. A light touch, tweezers, sharp soldering iron tip, and low heat (#7 tip) are recommended.

•

Power (+) and ground (-) are available at the battery terminals.

•

Be sure to service the instrument in an ESD-safe work area.

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2.2.2 Preventative maintenance Units that are used on a regular basis should have the following preventative maintenance performed at least every six months: 1. Visually inspect the thermometer for physical damage that might cause future product failure. 2. Clean the unit per the instructions in the User Guide supplied with the thermometer and/or per the instructions below. 3. Perform the Power on Self Test (page 7), Startup Display Test (page 7), and the Calibration Test procedure (page 16). Long Term Storage Remove the batteries from units that are to be stored for an extended period and not used. Regular Tests and Calibration Perform the following tests every 12 months regardless of storage and usage levels: 1. Replace the batteries (page 15). 2. Perform the Power on Self Test (page 7), Startup Display Test (page 7), and the Calibration Test procedure (page 16).

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2.2.3 Cleaning and Sterilization Routine Cleaning Clean the exterior of the Model 986 and the probe as needed. •

Use a Q-Tip to clean the probe well.

•

Wipe all surfaces with a clean cloth dampened with warm water and a mild detergent, alcohol, or a nonstaining disinfectant such as Sporicidin Spray1 and Towelettes cleanser.

Care should be taken not to scratch the LCD faceplate. Make sure that the cloth is damp, but not too wet. •

Do not allow cleaning solution to flow inside the instrument.

•

Never immerse the thermometer into the cleaning solution.

•

Never autoclave the thermometer or probe.

Gas Sterilization When no other form of decontamination such as a germicidal wipe is acceptable, a low temperature (not to exceed 48.9°C or 120°F) ETO gas sterilization cycle may be used. Refer to your institution’s standard operating procedure for the length of the cycle. Note: Gas sterilization may cause some hazing of glossy plastic surfaces and should be used only when absolutely necessary. 1. Remove the probe from its storage well and disconnect it from the instrument. 2. Remove any probe covers from the probe and from the probe cover storage well. 3. Remove the batteries following the instructions on page 15. WARNING: Leaving batteries in the thermometer during the sterilization procedure may present an explosion hazard. 4. Wrap the thermometer in standard sterilization packaging such as the Baxter Tower Dualpeel Sterilization Pouch. 5. ETO gas sterilize the instrument at a temperature not to exceed 48.9°C (120°F) and aerate. 6. Remove the sterilization packaging. 7. Allow the probe and instrument to stabilize to room temperature for at least one hour before reinstalling the batteries and probe. 1

Sporicidin is a registered trademark of Sporicidin International (800) 424-3733.

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8. Reinstall the batteries (see page 15) and verify a successful self-test. 9. Reinstall the probe connector and insert the probe into the storage well to start the probe initialization process. 10. Verify proper calibration of the thermometer and probe using the Welch Allyn Model 9600 Calibration Tester.

2.2.4 Service Activities Field Service Repairs Repairs are considered field serviceable if the repair will not alter the calibration or proper operation of the instrument. Recalibration requires a computer-based system and is normally performed at the factory. Factory Repairs Because of programming requirements, if problems are traced to microcontroller U1, the unit must be returned to the factory or properly equipped service center for repair.

2.2.5 Component Replacement All components in the Model 986 can be replaced without affecting instrument operation or calibration. Changing R13 will cause some minor changes to the exact calibration point, but as long as the proper type and tolerance resistors are used (0.05%, as supplied by Welch Allyn), the unit will remain within specifications. LCD Frame Repair or Replacement Replacement of the LCD frame is somewhat difficult due to the need to assemble it while under pressure to assure proper compression of the elastomeric connector. Note: Do not glue the LCD frame to the display PCB if the frame pins are broken. This will destroy the display PCB. Replace the LCD frame with a new LCD frame.

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2.3

Battery Removal and Replacement

Figure 5: Battery Removal and Replacement 1. Remove the Probe Cover box holder on the back of the instrument by pressing with your index finger on the latch located on the rear of the Probe Cover box holder. 2. Remove the batteries. 3. Press the Mode button for approximately five seconds to discharge the electronics. 4. Install two new AAA, alkaline batteries according to the battery polarities marked inside the battery compartment. Verify that the thermometer completes a power on reset test (page 7), and then goes blank. CAUTION: Incorrect battery polarity may result in damage to the thermometer. 5. Snap the probe cover storage assembly in place by inserting the bottom tabs first and then snapping the latch on top.

2.3.1 Battery Life Under normal use, battery life will provide approximately 3,000 normal temperature measurements, based on an average 22.2°C (72.0°F) ambient temperature. Colder ambient temperatures, excessive peak monitor measurements, and other usage patterns can reduce battery life. Instruments are shipped with fresh batteries, but we cannot guarantee full life from the first set of batteries due to potential long storage times between shipping and actual use. Battery life can also be reduced by storage at elevated temperatures. If you are experiencing short battery life, refer to Battery Life Problems in the Troubleshooting table on page 22.

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2.4

Calibration Procedures 2.4.1 Calibration Limits Table Patient Temperature Oral/Axillary

35.5° C to 43.0° C (96° F to 109.4° F)

Rectal

30.0°C to 43.0° C (86° F to 109.4° F)

Ambient Temperature Range

9.0° C to 40.0° C (48.2° F to 104.0° F)

Laboratory Accuracy

± 0.1° C (± 0.2° F) in the Monitor Mode In a water bath, must meet ASTM E1112-86 and EN12470-3 Standards

Battery Operating Life

Approximately 3,000 normal mode measurements at 22.2°C (72o F) ambient temperature

2.4.2 Water Bath procedure The target patient temperature for the M986 ranges from 96° F to

109.4°. 1. Adjust the water bath to 109.6°F. Apply a probe cover to the thermometer probe, and let the probe tip sit in the water bath. 2. Place the thermometer in Peak Monitor Mode (page 9). Wait three minutes. Verify that the water bath temperature is displayed on the LCD with the up arrow flashing. 3. For temperatures below the minimum target temperature, verify that the minimum temperature is displayed on the LCD, and the down arrow is flashing.

2.4.3 Variable Temperature Water Bath procedure Adjust the water bath to 46.0°F. Apply a probe cover to the thermometer probe, and let the probe sit in the water bath for one minute. 1. Press and release the Mode button. Verify that a Low Ambient error (E1.2) occurs, but that a probe A/D pulse width error (E0.2) does NOT occur. 2. Repeat with the water bath set to 106.0°F, and verify that a High Ambient error (E1.1) occurs, but that a probe A/D pulse width error (E0.2) does NOT occur.

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