
Contents
vi 4-070496-00 Rev. C (06/05) 840 Ventilator System Service Manual
2.4.1 Summary of electrical components ................................................................... 2-42
2.4.2 Overview of electrical system operation ............................................................ 2-47
2.4.3 AC distribution components ............................................................................. 2-50
2.4.3.1 Power cord ............................................................................................. 2-50
2.4.3.2 AC panel................................................................................................. 2-50
2.4.3.3 Power switch........................................................................................... 2-53
2.4.4 Power supply .................................................................................................... 2-54
2.4.5 BPS ................................................................................................................... 2-56
2.4.6 Card Cage ........................................................................................................ 2-58
2.4.6.1 Motherboard PCB ................................................................................... 2-60
2.4.6.2 BDU CPU PCB ......................................................................................... 2-63
2.4.6.3 Analog interface (AI) PCB ........................................................................ 2-67
2.4.7 Data key subsystem .......................................................................................... 2-69
2.4.8 GUI................................................................................................................... 2-69
2.4.8.1 GUI CPU PCB ......................................................................................... 2-69
2.4.8.2 Touch frame PCB .................................................................................... 2-75
2.4.8.3 Keyboard assembly with knob................................................................. 2-76
2.4.8.4 GUI LED PCB........................................................................................... 2-78
2.4.8.5Backlight inverter PCB and LCD lamps ........................................................ 2-79
2.4.8.6 GUI alarm assembly ................................................................................ 2-80
2.4.9 BDU LED PCB ................................................................................................... 2-81
2.4.10 Inspiratory electronics PCB.............................................................................. 2-81
2.4.11 Exhalation transducer PCB .............................................................................. 2-83
2.4.11.1BD (continuous-tone) alarm assembly....................................................... 2-85
2.4.12 806 Compressor unit ...................................................................................... 2-85
2.4.12.1806 compressor unit AC power distribution components and motor ........ 2-86
2.4.12.2 806 compressor PCB............................................................................... 2-86
2.4.12.3806 Compressor unit operation ................................................................ 2-90
2.5 Breath delivery.......................................................................................................... 2-92
2.5.1 Inspiration......................................................................................................... 2-92
2.5.1.1Pressure triggering...................................................................................... 2-94
2.5.1.2 Flow triggering ....................................................................................... 2-94
2.5.1.3 Time-cycling method .............................................................................. 2-94
2.5.1.4 Operator triggering................................................................................. 2-94
2.5.2 Exhalation......................................................................................................... 2-94
2.5.2.1Time-cycling method.................................................................................. 2-95
2.5.2.2 End-inspiratory flow method................................................................... 2-95
2.5.2.3 Airway pressure method.......................................................................... 2-95
2.5.2.4 Time limit................................................................................................ 2-95
2.5.2.5 High circuit pressure limit........................................................................ 2-95
2.5.2.6 High ventilator pressure limit .................................................................. 2-95
2.6 Other hardware operations ...................................................................................... 2-97
2.6.1 Gas supply and control ..................................................................................... 2-97
2.6.2 Data monitoring ............................................................................................... 2-97
2.6.3 Pressure transducer autozero............................................................................. 2-98
2.6.4 Power monitoring and power fail handling ..................................................... 2-100
2.6.4.1 Loss of power source............................................................................. 2-100
2.6.4.2 Supply voltage monitoring.................................................................... 2-101
2.7.1 Safety valve open (SVO) state.......................................................................... 2-101