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3
MODULE DESCRIPTION
Inmarsat B
3.2.5
SMI BOARD
The switch mode power supply and interconnection board consists basically of two independent units.
The interconnection takes care of the interface between SUB-D connectors at the rear panel of the
transceiver unit and the modules inside it. A block diagram is shown in fig. 3.2.5.
Power
Ant.
Scanbus
NMEA
Data
Pc/Printer
Alarm
Phone 2
Phone 1
X1
X2
X3
X4
Ribbon cable connectors to transceiver modules
Rear panel connectors
Connection circuit
Filter
40V DC Conv.
40V DC Conv.
40V DC Conv.
Multi Conv.
Control circuit
DC/DC Conv.
-12V
+12V
+40V
-15V
+15V
+24V
+8V
35970
Fig. 3.2.5.
The supply voltage delivered from the ship to the transceiver unit is 24V DC nominal but can range from
20 to 40V DC. From the input voltage, the switch mode power supply generates the following voltages:
+40V DC
-
7A
+12V DC
-
0.1A
-12V DC
-
0.1A
+15V DC
-
0.25A
-15V DC
-
0.15A
+7.5V DC -
2.6A
+24V DC
-
0.4A
The switch mode power supply is built up as four converter modules, placed on a main board containing
all the DC control circuits. Three of the converter modules generate 40V DC and are coupled in parallel,
i.e. only one 40V DC is available. The fourth converter is a multi converter generating all internally used
voltages in the transceiver unit. The 40V DC is used as main voltage for the antenna unit, as input for the
multiconverter and finally as input for a special DC/DC converter placed on the main board generating
±12V DC for RS 232 terminals connected to the transceiver unit.
All the converters are placed inside a metal screen to prevent emission of noise. A heat sink is placed
on top of the converters. Therefore, when the transceiver unit is working, the blower inside the transceiver
unit must always be connected.
40V DC converter module
This module is a push-pull converter, basically controlled by a current mode controller, which is controlled
and synchronised by the control circuit on the main board.
Multiconverter module
This module contains two converters. The first one is a step DOWN converter converting the 40V DC
down to 7.5V DC which supplies the 5V regulators placed on the different boards inside the transceiver
unit.
The second converter is a fly back version, which creates ±15V DC for the transceiver modules and +24V
DC mainly used to supply the control unit and handset.
The multiconverter is also synchronised with the 40V DC converters.
PAGE 3-21
9936
Summary of Contents for Inmarsat B
Page 1: ...SAILOR Inmarsat B Workshop Manual W4400GB0 ...
Page 2: ...Inmarsat B Workshop Manual 9905 ...
Page 7: ...CONTENTS 1 INTRODUCTION 1 1 1 1 SYSTEM COMPONENTS 1 2 1 2 TECHNICAL DATA 1 2 9849 Inmarsat B ...
Page 46: ...4 ACCESSORIES Inmarsat B PAGE 4 3 Inmarsat B 9849 Diagram Veritas connection box ...
Page 124: ...CONTENTS 8 PERFORMANCE CHECK AFTER REPAIR 8 1 8 1 START UP SEQUENCE 8 1 9936 Inmarsat B ...
Page 127: ...CONTENTS 9 SERVICE 9 1 9 1 CHECK OF OCXO 9 1 9936 Inmarsat B ...
Page 129: ...CONTENTS 10 PARTS LISTS 10 1 9901 Inmarsat B ...
Page 133: ...CONTENTS 11 ABBREVIATIONS 11 1 Inmarsat B 9849 ...