In this way, a patient airway temperature greater than 41 °C causes both heaters to be shut down. A watch dog failure, which is a high output from U5g, is communicated via isolating diode D11 and resistor R31 to the inverting input of U10c. This also ensures that both heater control circuits are clamped off in the event of a processor crash. 4.2.8 HEATERPLATE OVERTEMPERATURE Thermistor HP senses the heaterplate temperature. Should the heaterplate exceed the maximum heaterplate limit (default 110

Tel: +33–(0)1-6446-5201 Fax: +33–(0)1-6446-5221 USA: Suite 101 22982 Alcalde Drive, Laguna Hills, California 92653, USA Tel: +1-(949)-470-3900 Fax: +1-(949)-470-3933 Toll Free: (800)-446-3908 UK and Ireland(European Authorised Representative): Unit 16, Cordwallis Park Clivemont Road, Maidenhead, SL6 7BU, United Kingdom Tel: +44-(0)1628626 136 Fax: +44-(0)1628626 146 MR850 Technical Manual * Revision J * Issued November 2005 * Ref. 185041340 (185041713 internal) TABLE OF CONTENTS 1 INTRODUCTION .

Revision F changes, Section Description of Change 6.0 Routine Performance test shortened (Dynamic test removed). 7.33 Software Compatability Updated 8.10 Spares list additions 9.0 Change history updated Appendix B Maintenance Schedule Changed for Temperature Probes Appendix D Cleaning Procedures Rewritten Appendix E Dynamic performance check made an optional extra Ref. 185040646 *MR730/720/700/480 Technical Manual . Revision F . Issued March 2001 iii CONTENTS PAGE 1.0 MR700 SERIES GENERAL SPECIF

Cut the cable tie holding the heaterplate and chassis wires together. The power board and heat sink assembly can now be removed by flexing the case sides away from the top edge of the board and moving the board forward slightly to disengage from the case. The board should now be lifted slightly to clear the lower retaining guides and moved further forward to gain access to the various wiring harness connectors which can now be detached. Before removing the PCB, unscrew the mains cord connections

• Display Test All indicator LEDs are illuminated and ‘8.8.8.’ is displayed on the Airway Temperature display · Model Number eg ‘730’ · Software Version Number eg ‘2.0’ · Temperature Control Setting eg ‘37.0’ is displayed • Chamber Control setting If heater wire mode is selected then the chamber control setting is displayed eg ‘-1.0’. Not applicable for MR480 · Maximum Heaterplate setting eg ‘110’ · Audio Beep 2.4 HEATER WIRE ON MODE (ALL MODELS EXCEPT MR480) In the Heater Wire On Mode (heater w