Schiller AT-2 - Main Board MK 12-1

Page 2.3
Chapter 2
Functional Overview
SCHILLER AT-2 6-Channel ECG Unit SERVICE HANDBOOK Issue 2.1 November 1998
PRINTER
ASSEMBLY
Paper mark
detector
Thermal print
head
Printer motor
TOP CASING
Batt. LED,
Lead LEDs,
Filter, Elec-
trode loose
Keyboard
Print head
controller
Stepper motor
controller
LED Decoder /
Keyboard
interface
System
Software
EPROM
CPU /
decoder /
Timer
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
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7
1234567
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
123 123
12 12 12 12
12 12 12
12 V
Battery
Mains
LED
Mains
con-
nector
+U
123 123
1234 1234
1234 1234
123 123
123 123
MAIN BOARD MK 12-1
TP 12 & TP 13
P3 (part)
P3 (part)
P2
P5
P4
P1
P1
+Batt
MUX
CTRL
SI3
SI1
SI2
ON from keyboard
OFF from CPU