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Service manual CS3000
Chapter 3: Input board INK-2 3-21
The circuit boards of the central unit
Document no.:
S-4-007.875/E
Prepared:
1995-03-17 Fia
Revision:
R4 2004-03-15 BM
© 2002, Consilium Marine AB
1. DC/DC converter
The DC/DC circuit converts the battery voltage of the back plane to 5 VDC,
which is supplied to all logical circuits on the board. Should the voltage
disappear, a signal is activated in the back plane.
2. Supervision
The battery voltage is fused. If the fuse is blown a signal is activated in the
back plane. The fuse is accessible on the front panel of the board, and can be
used for disconnecting the power.
3. LED indications
On the front panel are two green LEDs for indicating 5V power and normal
polling.
4. Control logic
The control logic is used for decoding the address bus and for generating
signals to read/write the status register and read the input buffers.
5. & 6. Buffers
The address bus, the data bus and the control signals are buffered before
entering the board.
7. Status register
The status register is a read/write register. On reset the status is zeroed. Thus it
is possible to check the function of the board.
8. Input buffers
The signals on the inputs are buffered before entering the data bus.
9. Opto-isolated inputs
The inputs are divided into six groups, where each group has a common return
conductor. The inputs are protected by transient suppressors. Each input is
equipped with an LED that is lit when the input is active. These LEDs are not
visible from the front panel.