Schiller AT-2plus - Page 38

Page 2.3
Chapter 2
Functional Overview
SCHILLER AT-2plus 6-Channel ECG Unit
SERVICE HANDBOOK Issue d May 2002
PRINTER
ASSEMBLY
Paper mark
detector
Thermal print
head
Printer motor
TOP ASSEMBLY
LCD screen
Keyboard
RS-232
INTER-
FACE
Print head
controller
Stepper motor
controller
LCD controller
Keyboard
interface
FLASH
EPROM
memory
CPU
DC - DC
converter
reference
voltage
Power rail
stabilisation
Signal multi-
plexer (PWM)
AC - DC
converter
Input amplifier
and filter
DC - AC
converter
400 kHz
+5Vi
+2Vi
+5Vi
-5Vi
-10Vi
+5.2Vi
Patient
connector
PATIENT ISOLATION (4kVrms)
Voltage
regulator
Voltage
regulator
Switching
voltage reg.
+5V ref
+5.2V
+24V
Overvoltage
protection
Undervoltage
protection
Voltage sense
& conversion
MON
Motor running
BLOW
10.3V MON
+US
ON / OFF
control
Battery charger &
voltage regulator
Rectification
Voltage sense+US
+US
+5.2V
+24V
12 V
Battery
Mains
LED
Mains
con-
nector
+U
MAIN BOARD MK 14 - 10
LCD power
supply
P6
P4 (part)
P10
P4
P9
P5
P3
P2
P2
P1
P1
MUX
CTRL
+Batt
OFF from CPU
ON from keyboard
SI1
SI2