Welch Allyn SureTemp 767 Technical Manual
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Welch Allyn SureTemp 767 Technical Manual

Welch Allyn SureTemp 767 Technical Manual

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Summary of Contents for Welch Allyn SureTemp 767

  • Page 1 ® SureTemp Model 767 Thermometer Technical Manual...
  • Page 3 © 1999 by Welch Allyn. 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. Printed in the USA...

  • Page 5: Table Of Contents

    TABLE OF CONTENTS WARRANTY ............................4 SPECIFICATIONS ..........................5 OPERATIONAL CHARACTERISTICS ....................5 Introduction............................5 Basic System Description ........................5 SAFETY & WARNINGS........................7 SELF TESTS ............................7 Instrument Reset/Self Tests......................7 Display Test ..........................8 Probe Warmer Circuit Self Tests ....................8 THERMOMETER MODES ........................9 Normal Mode ...........................9 Monitor Mode...........................9 Biotech Mode..........................10 Biotech Mode Program Table ......................10 Temperature Recall ........................11...
  • Page 6 Welch Allyn Model 767 Basic Function ..........................17 Circuit Operation.........................17 Reset/Self Tests ..........................18 Power Supply ..........................18 Other Components ........................18 Microcontroller ..........................18 Microprocessor Clock .........................18 Liquid Crystal Display .........................19 Backlight (Optional) ........................19 Horn ……………………………………………………………………………………………………….19 Probe Switch..........................19 Serial Communications Port......................19 Mode Button ..........................19 Thermometer Modes (Theory of Operation)..................20...
  • Page 7 Technical Manual TABLE OF FIGURES FIGURE 1 - THERMOMETER DIAGRAM .....................6 FIGURE 2 - M767 DISPLAY .........................8 FIGURE 3- SYSTEM BLOCK DIAGRAM ....................14 FIGURE 4 - PROBE LOGIC........................17 FIGURE 5 - THERMOMETER ASSEMBLY DRAWING ..............32 FIGURE 6 - PRINTED CIRCUIT ASSEMBLY ..................33 FIGURE 7 - SYSTEM SCHEMATIC....................34...

  • Page 8: Warranty

    Welch Allyn, Inc. is warranted to be free from original defects in material and workmanship under normal use and service for a period of three years from the date of first shipment from Welch Allyn. This warranty shall be fulfilled by Welch Allyn or its authorized representative repairing or replacing at Welch Allyn's discretion, any such defect, free of charge for parts and labor.

  • Page 9: Specifications

    OPERATIONAL CHARACTERISTICS Introduction The Welch Allyn 767 SureTemp is a wall mounted thermistor thermometer to be used for measuring patient temperatures ranging from 84 °F to 108 °F (28.9 °C to 42.2 °C). Oral and rectal temperatures are taken using Normal or Monitor operating modes. Axillary temperatures are taken with an oral probe with the unit operating in the Axillary mode.

  • Page 10: Figure 1 - Thermometer Diagram

    Welch Allyn Model 767 Welch Allyn’s M678/679 thermistor probes used with 767 thermometers can be identified by color combinations as follows: Handle Top Color Connector Model # Probe Type Color Color/Type Fog White Blue Fog White, M678 Oral/Axillary Latching Fog White...

  • Page 11: Safety & Warnings

    SAFETY & WARNINGS CAUTION: DISCONNECT THE SYSTEM FROM THE MAINS SUPPLY BEFORE CONNECTING THE 767 SURETEMP THERMOMETER. USE THE 767 SURETEMP WITH WELCH ALLYN 3.5V 767 SERIES WALL TRANSFORMER ONLY. DO NOT USE IN THE PRESENCE OF FLAMMABLE ANESTHETICS. Caution: Federal (USA) law restricts this device to sale by or on the order of a physician.

  • Page 12: Display Test

    Welch Allyn Model 767 Display Test The display test begins with each display segment and icon being individually lit in brief and rapid succession. Immediately after this, all display segments and icons are simultaneously illuminated briefly followed by a display of the software revision in this instrument. The beeper also briefly sounds at the beginning of the test.

  • Page 13: Thermometer Modes

    Technical Manual THERMOMETER MODES Normal Mode After instrument and probe warmer self tests, the system is ready for use. 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 storage well. 1.

  • Page 14: Biotech Mode

    Monitor mode is also useful in testing the accuracy of the combined probe/instrument system when the probe can be warmed to a known temperature, as with a Welch Allyn Model 9600 Calibration Tester or in a circulating water bath set to a known temperature.

  • Page 15: Temperature Recall

    Technical Manual 2. Default Algorithm Three settings are available to set the default predictive Oral/Axillary Modes algorithm: oral(OrL), axillary(ALY) or last prediction(LSt). To change the default algorithm, momentarily press the Mode button to advance to the next algorithm. The instrument will be placed in the selected algorithm after the probe has been returned to the probe well.

  • Page 16: Preventative Maintenance

    6. Remove the sterilization packaging. 7. Before applying power, allow the probe and instrument to stabilize to room temperature for at least one hour. 8. Verify proper calibration of the thermometer and probe using the Welch Allyn Model 9600 Calibration Tester.

  • Page 17: Calibration Testing

    9600 Calibration Tester. Refer to the Model 9600 Calibration Tester Operation Manual for complete instructions. Note: All Welch Allyn and Diatek thermometers (thermistor and infrared ear thermometers) can be checked in the Model 9600.

  • Page 18: Temperature Measurement A/D Converter

    Welch Allyn Model 767 MODEL 767 PCA Test Port J3 NEC UPD78064 uP Serial Port Serial 16 bit Converter Timer Circuitry Mode Button Voltage Driver Reference Horn Horn Driver Circuitry Backlight Circuit Liquid Probe Probe AC TO DC Crystal Warmer...

  • Page 19: Circuit Description

    Technical Manual In effect, this is a single slope converter which measures the time constant of the measured resistance combined with a fixed capacitance. The time constant is measured by counting the time it takes for the voltage to decay from a fixed initial voltage level to a fixed lower voltage. The ratio of this pulse width and the pulse width corresponding to a known calibration resistance (R13, 11.55K) is used to calculate the measured resistance.

  • Page 20: Probe Warming ( Oral Probes Only)

    Welch Allyn Model 767 · D4 and R16 protect the comparator from input undervoltage when the timing capacitor (C21) is discharged. D4 also reduces the recovery time by limiting the voltage at the beginning of recovery to 0.6 volts instead of 2/3VREF.

  • Page 21: Probe Identification Logic

    Technical Manual During normal operation, software turns the warmer circuit on and off. The width of the pulse on HTRC determines how long Q5 is turned on, thereby determining how long the heater is heating. Once the HTRC pulse goes high again, the base of Q5 is pulled high turning it off, and the capacitor discharges to VCC through D1.

  • Page 22: Reset/Self Tests

    Welch Allyn Model 767 · When J1-3 (CAL) is connected to J1-5 (GND), but J1-6 (RCTL) is not connected to J1-5 (GND), the software determines that the probe is Rectal probe; · When J1-6 (RCTL) is connected to J1-5 (GND), but J1-3 (CAL) is not connected to J1-5 (GND), the software determines that the probe is a Calibration Key;...

  • Page 23: Liquid Crystal Display

    Technical Manual Liquid Crystal Display The Model 767 uses a liquid crystal display to display data to the user. Three communication lines and 18 segment lines connect the LCD to the display driver (U1-60 to U1-77) internal to the NEC microprocessor.

  • Page 24: Thermometer Modes (Theory Of Operation)

    Welch Allyn Model 767 display), pressing the Mode Button will wake up the thermometer and display the last recorded Normal mode temperature. Thermometer Modes (Theory of Operation) Monitor Mode The Monitor mode is selected manually by the Mode button (S1) on the right side of the instrument.

  • Page 25: Troubleshooting

    Technical Manual TROUBLESHOOTING Many thermometer operational parameters can be tested for proper operation before the unit is taken apart and without needing any tools. Refer to Operational Characteristics on page 5 and in particular to the Self Tests and Biotech Mode sections for guidance on preliminary checks. If the trouble seems to be calibration related, refer to Calibration Testing on page 13.

  • Page 26: Equipment Required

    Welch Allyn Model 767 Internal E5.2 Heater watchdog timeout test. Internal E6.0 PTB resistor “temperature” test. Note: Error codes E0.1, E0.2, E0.3, can sometimes be caused by a faulty probe. It is advisable to remove the probe completely from the instrument and check its functionality as described in the Operational Characteristics section before assuming an instrument problem instead of a probe problem.

  • Page 27: Troubleshooting Table

    Technical Manual Below is a table which can be used to determine the cause of a particular problem: Troubleshooting Table SYMPTOM POSSIBLE CAUSE PROCEDURE No power to unit Make sure its power supply is plugged in and turned on. Make sure the power supply is providing between 5.9 and 10 Volts AC.
  • Page 28 Welch Allyn Model 767 Display problems Dirty, or crooked Remove Display PCA by opening the case and unscrewing the elastomeric LCD 8 Torx screws on the Display PCA. Clean LCD elastomeric conductor (zebra) strips, LCD glass contacts, and PCB contacts with lint proof strips.
  • Page 29 Technical Manual Normal/ Ambient above Causes auto switch to Monitor mode. Monitor 33.9°C (93.0°F) Mode switching problems If 60 seconds pass after ready in Normal mode, unit Switched to Monitor switches to Monitor mode. mode before probe in mouth. If probe is still cooling from a previous temperature and used immediately, it might sense ambient to be above 93.0°F (33.9°C).
  • Page 30 Welch Allyn Model 767 Cal Key Defective Cal Key Replace Calibration Key shows OrL, rEC, or ALy Monitor Probe malfunction Change probe. mode temperature Test calibration of entire system (instrument and probe) reading too with the M9600 Calibration Tester. low.

  • Page 31: Field Serviceable Repairs

    Technical Manual Instrument Check calibration with Calibration Key. malfunction Probe must be under the tongue and as far back as Improper placement possible into the sublingual pocket. of probe. Normal Probe malfunction. Re-characterize probe. (remove completely from mode instrument and re-install.) temperature reading too Change probe.

  • Page 32: Field Serviceable Parts

    Some minor changes to the exact calibration point will be caused by changing R8, and R13, but as long as the proper type and tolerance resistors are used (0.1% and 0.05% as supplied by Welch Allyn), the unit will remain within specifications. FIELD SERVICEABLE PARTS All parts are serviceable by qualified technicians.

  • Page 33: Replacement Parts-Circuit Board Assemblies

    Technical Manual 81054-0000 WASHER, FIBER .187 OD X .089 ID .031 THK 83047-0000 SCREW, MACH 6-32 X 1/4 P-PL-S-Z 83140-0000 SCREW, MACH 6-32 X 1/4 SEMS, INTTOOTH P-PL-S-Z 83166-0000 SCREW, PLASTITE #2-28 X 1/2 LONG TORX, PAN HEAD 83167-0000 SCREW, PLASTITE #2-28 X 1/4 LONG TORX, PAN HEAD 83169-0000 SCREW, 2-56 X 3/8 SEMS, INTERNAL, P-PL-S-Z 85254-0000...
  • Page 34 Welch Allyn Model 767 43011-0000 Ferrite FR1,FR2 58529-0006 6 Pin Connector 58529-0003 3 Pin Connector 58524-0000 6 Pin Connector (Connector PCB) J201 80174-0000 24 Pin Cable (J2 to J6) 58516-0000 AC Contact J7, J8 43010-0000 Inductor 10uH 43009-0000 Inductor 220uH...

  • Page 35: Thermometer Disassembly

    Technical Manual 54272-0000 Econo Reset DS1810 54266-0000 2.4V Regulator TC45ER 48001-0000 Varistor 47021-0000 Crystal 4.9152MHz THERMOMETER DISASSEMBLY Please note that if your thermometer is within the warranty period, you should return the unit to an authorized service representative for servicing; failure to do so may invalidate the warranty.

  • Page 36: Figure 5 - Thermometer Assembly Drawing

    Welch Allyn Model 767 Caution: While lifting the LCD out of the Front housing, do not allow it to slide along or drop on the plastic window. This could leave visible scratches on the plastic window. Note: Bubble Numbers refer to Item #’s in Replacement Parts List.

  • Page 37: Figure 6 - Printed Circuit Assembly

    Technical Manual FIGURE 6 - PRINTED CIRCUIT ASSEMBLY...

  • Page 38: Figure 7 - System Schematic

    CONFIDENTIAL AND PROPRIETARY ALLYN. IT IS SUBMITTED IN CHECK Dennis Wade 1/25/99 TITLE CONFIDENCE AND IS NOT PROPERTY OF WELCH ALLYN INC. TO BE DISCLOSED OR PROJ. MGR. M. Bowyer 1/25/99 S C H E M A TIC, M767 ENHANCED UTILIZED WITHOUT WRITTEN PERMISSION.

  • Page 39: Thermometer Reassembly

    Technical Manual THERMOMETER REASSEMBLY If the Display PCA has been removed from the Front housing, lay the Front housing on a flat surface. Ensure that the LCD and zebra strips have been installed into the Front housing (the bump on one end of the LCD should be to the right as you look in the back of the Front housing). Then, carefully install the Display PCA into the Front housing.

  • Page 40: Accessories

    Welch Allyn Model 767 SUGGESTED SPARE PARTS LIST PART NO. DESCRIPTION QTY PER 100 UNITS 20991-0000 ASSY, CONNECTOR PCA WITH CABLE & FERRITE BEAD 58101-000 PROBE SWITCH 81054-0000 WASHER, FIBER .187 OD X .089 ID .031 THK 83166-0000 SCREW, PLASTITE #2-28 X 1/2 LONG TORX, PAN HEAD...
  • Page 41 Technical Manual 7420 Carroll Road, San Diego, California 92121 • (800) 854-2904 • (858) 621-6600 • FAX (858) 621-6610 70841-0001 B...

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