Respironics ESPRIT, Руководство по обслуживанию, Страница: 29 / 329

Chapter 3
Theory of Operation
REF 580-1000-02 G Esprit® Ventilator Service Manual © Respironics, Inc.
3-15
Man-Machine Interface (MMI) PCB
The MMI PCB interfaces the front panel overlay, VGA display, rotary encoder,
and touch screen to the CPU via the main PCB. The MMI PCB contains control
circuitry for the primary and back-up alarms, and includes the hard keys and
LEDs on the front panel membrane keypad.
Power Supply
The power supply converts AC voltage to DC voltage to be used by the system
electronics. The switching power supply can accept voltage from 100 to 240 V
AC (50/60 Hz), and converts it to +5 V, + 12 V, and +29 V DC voltages. In the
absence of AC voltage, the power supply converts the +24V DC input voltage
from an external DC power source (Backup Battery or External Battery). The
power supply also includes power fail logic and charging circuitry for the
backup battery.
Backlight Inverter PCB
For 9.5-in. displays: the backlight inverter PCB converts 5 V to approximately
500 V to drive the backlight on the VGA display assembly.
For original 10.4-in. displays: the backlight inverter PCB converts 12 V to
approximately 500 V to drive the backlight on the VGA display assembly.
For 2nd generation 10.4-in. displays: the backlight inverter PCB converts 5V
to approximately 500V to drive the backlight on the VGA display assembly.
WARNING: The backlight inverter PCB generates high voltage. To avoid personal injury,
verify that the AC and external DC power sources (Backup Battery or External
Battery) are disconnected from the ventilator.
Real-Time Clock Battery
The real time clock battery is a 3.6-V lithium battery that supplies power to the
real time clock on the VGA controller PCB when ventilator power is off.
Backup Battery
The optional Backup Battery can power the ventilator for approximately 30
minutes under nominal settings if AC power is lost.