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March 2021
Page 112 of 143
59812-K007 Rev 17
Business Confidential
Note: To maintain the warranty for the Control Unit changing of the battery should be performed
by an approved Service Engineer.
The OMD Mk7 system can function independently of the RDU allowing the RDU to be disconnected whilst
the rest of the OMD system remains in operation. In this case the Modbus connector should be removed
BEFORE removing the 24V input to the RDU.
The procedure to replace the battery is as follows:
1.
Remove the RDU from its mounting position, disconnect the Modbus connector followed by the 24V
power connector from the base of the unit.
2.
Place the RDU face down and remove the six screws which locate the rear cover.
In the case of a bulkhead mounted RDU the backbox must be removed first by removing the 4 screws
on the side. Please be mindful of the captive nuts within a bulkhead mounted RDU as these may slide
out during disassembly.
3.
The RDU should be turned face up after removing the screws prior to removing the front cover, this
will prevent the captive nuts from falling out of their holders.
4.
Care should also be taken not to pull the connecting cables when lifting the RDU cover. The easiest
way is to lift the lid and flip it down.
5.
Check that the blue plug in board is seated correctly and fitted firmly in its socket.
Figure 173
Real Time Clock Battery Location
6.
Note the orientation the existing battery, see Figure 174 (the positive terminal is facing outwards)