Chapter 3
3-10
Esprit® Ventilator Service Manual © Respironics, Inc.
REF 580-1000-02 G
Theory of Operation
The CPU interfaces with the pneumatics and displays through the main PCB
and daughter boards that are vertically mounted on the main PCB. The
daughter boards include the CPU PCB, digital PCB, analog PCB, VGA
controller PCB, and three stepper motor controller PCBs.
The digital control signals from the CPU are sent to the analog PCB where they
are converted into analog signals that control blower speed and chart recorder
outputs (pressure, flow, and volume). Analog data from the flow, pressure, and
oxygen sensors is conditioned and converted by the sensor PCB. The sensor
PCB conditions and coverts the data, and sends it to the analog PCB, where it
is read by the CPU.
Ventilator data from the CPU is conditioned by the VGA and man-machine
interface (MMI) PCBs, then displayed on an LCD.
The following table summarizes the electronic signal path for Esprit
components.
Component
Signal Path Sequence
100% O
2
indicator
Front panel overlay, MMI PCB, main PCB, digital PCB, CPU
PCB
29 V Enable
Main PCB, CPU PCB, power supply
Air (AV), oxygen (OV), exhalation
(EV) valves
Main PCB, motor controller PCB, CPU PCB
Air (FS1), oxygen (FS2), exhalation
(FS3) flow sensors
Sensor PCB, main PCB, analog PCB, CPU PCB
Alarm High
Indicator
Front panel overlay, MMI PCB, main PCB, CPU PCB
Alarm Med/Low
Indicator
Front panel overlay, MMI PCB, main PCB, CPU PCB
Alarm Silence Indicator
Front panel overlay, MMI PCB, main PCB, digital PCB, CPU
PCB
Backlight (9.5-in. display)
Backlight inverter PCB, MMI PCB, backlight control
potentiometer.
Backlight (10.4-in. display)
Backlight inverter PCB, DC/DC converter PCB, main PCB,
backlight control potentiometer
Backup Alarm
MMI PCB, main PCB, digital PCB, CPU PCB
Backup Battery, External Battery
Power supply
Battery/Charging
Indicator
Front panel overlay, MMI PCB, power supply, main PCB,
CPU PCB
Battery/In Use
Indicator
Front panel overlay, MMI PCB, main PCB, digital PCB, CPU
PCB
Battery/Low
Indicator
Front panel overlay, MMI PCB, digital PCB, CPU PCB
Blower DAC
Blower controller PCB, sensor PCB, main PCB, analog PCB,
CPU PCB
Blower on/off
Blower controller PCB, sensor PCB, main PCB, CPU PCB
Blower temperature switch
Sensor PCB, main PCB, digital PCB, CPU PCB
Console: all keys
Front panel overlay, MMI PCB, main PCB, CPU PCB