Welch Allyn SureTemp 986 User manual
Service Manual
Thermo Menu
Operator Manual
®
SureTemp
Model 986 Thermometer
Welch Allyn, Inc.
7420 Carroll Road
San Diego, CA 92121
70995-0000B Technical Manual M986 © 2001
© 2000, 2001 by Welch Allyn, Inc. All rights reserved. No part of this manual may be
reproduced or transmitted in any form or by any means, electronic or mechanical, including
photocopy, without prior consent in writing from Welch Allyn, Inc. Printed in the USA
Welch Allyn and SureTemp are trademarks of Welch Allyn, Inc. All rights reserved.
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 Types of units ................................................................................................5
2.1.2 Major Thermometer Components .....................................................................6
2.1.3 Instrument Reset ........................................................................................... 6
2.1.4 POST (Power Up Self-Test)............................................................................. 7
2.1.5 Probe Type Test ............................................................................................ 7
2.1.6 Operational Checks........................................................................................ 8
2.1.7 Default algorithm for oral and axillary modes (blue probe) ................................11
2.2 Service Procedures .................................................................................................11
2.2.1 List of Tools and Equipment..........................................................................11
2.2.2 Preventative maintenance.............................................................................12
2.2.3 Cleaning and Sterilization .............................................................................13
2.2.4 Service Activities ..........................................................................................14
2.2.5 Component Replacement ..............................................................................14
2.3 Battery Removal and Replacement ...........................................................................15
2.3.1 Battery Life..................................................................................................15
2.4 Calibration Procedures............................................................................................16
2.4.1 Calibration Limits Table ................................................................................16
2.4.2 Water Bath procedure ..................................................................................16
2.4.3 Variable Temperature Water Bath procedure...................................................16
2.4.4 Model 9600 Calibration procedure ..................................................................17
3. 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
Model 986 Thermometer i
3.4.3 Replacement Parts for PCA ..........................................................................27
Appendix A. Theory of Operation.....................................................................................29
A.1 Overview................................................................................................................29
A.1.1 Temperature Probes.....................................................................................30
A.1.2 Probe Switch...............................................................................................30
A.1.3 Normal Mode Description..............................................................................30
A.1.4 Power Supply..............................................................................................31
A.1.5 Microcontroller.............................................................................................31
A.1.6 Reset/Self Tests..........................................................................................31
A.1.7 Microprocessor Clock...................................................................................32
A.1.8 Temperature Measurement And Display.........................................................32
A.2 Temperature Measurement A/D Converter .................................................................32
A.2.1 Use of Analog Circuitry.................................................................................32
A.2.2 A/D Theory of Operation ...............................................................................32
A.2.3 Circuit Description........................................................................................33
A.2.4 Probe Type Detection ...................................................................................34
A.2.5 Instrument ID Logic......................................................................................34
A.2.6 Circuit Operation ..........................................................................................34
A.3 Probe warming (Oral probes only)............................................................................35
A.3.1 Theory of Operation ......................................................................................35
A.3.2 Circuit Operation ..........................................................................................35
A.3.3 Liquid Crystal Display ...................................................................................36
A.3.4 Probe Switch...............................................................................................36
A.3.5 Mode Button................................................................................................36
A.3.6 Horn ...........................................................................................................37
Appendix B. Specifications .............................................................................................. 39
Appendix C. Limited Warranty ......................................................................................... 41
Appendix D. Wiring Diagram ...........................................................................................43
ii 70995-0000B M986
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
Model 986 Thermometer iii
iv 70995-0000B M986
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
A/D Converter
Circuit
Voltage
Reference Circuit
Battery Detector
Circuit
NEC UPD 789407 uP
16 Bit
Timer
8 Bit
A/D
Probe Warmer
Circuit
Four Conductor
Coil Cord
Thermistor
Probe Assembly
Probe
Warmer
CPU
LCD
Driver
Liquid Crystal
Display
Probe
Configuration
Jumpers
Serial
I/O
Horn
Driver
2 AAA
Batteries
Configuration
Serial
Port
Mode
Button
Horn
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
Model 986 Thermometer 1
800-535-6663
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
1.4 Classifications
Type of protection against
Degree of protection against
Degree of protection against
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.
Internally Powered Equipment
electric shock
Type BF Applied Part
electric shock
Ordinary (IPXO)
ingress of liquids
Degree of safety in the
presence of flammable
anesthetics
Mode of operation Continuous
2 70995-0000B M986
Equipment not suitable for use
with flammable anesthetics
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
1. General Information
Contact Welch Allyn Customer Service at (800) 535-6663 before
returning an M986 Thermometer to the factory for service.
Model 986 Thermometer 3
1. General Information
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
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
4 70995-0000B M986
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
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.
6 Battery Compartment
Figure 2: Model 986 Thermometer
Model 986 Thermometer 5
2. Service
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
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).
Allyn PN 05031 is not allowed, and will affect
the accuracy of the instrument.
6 70995-0000B M986
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
2. Service
• 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.
Model 986 Thermometer 7
2. Service
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.
8 70995-0000B M986
2. Service
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.
Model 986 Thermometer 9
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