UM582127000 User Instructions
Issue AC, January 2, 2013 Spec. No. 582127000 (Model 721NPBB)
Page 48 Chapter 4. Troubleshooting and Repair
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Optional LVD Driver and LVD Driver Lite Circuit Card Replacement
Procedure
1) Performing this procedure may activate external alarms. Do one of the following.
If possible, disable these alarms. If these alarms cannot be easily disabled,
notify the appropriate personnel to disregard any future alarms associated with
this system while the procedure is being performed.
Danger: Performing the next steps exposes service personnel to battery
potential. Exercise extreme caution not to inadvertently contact or
have any tool inadvertently contact any energized electrical
termination.
2) Open the distribution cabinet’s front door by turning the latch in the
counterclockwise position.
Warning: Damage to the circuit card may result if the next step is not followed.
3) Connect an approved grounding strap to your wrist. Attach the other end to a
suitable ground.
4) If any of the low voltage disconnect contactors is open and it is desired to be
closed, push the LVD Inhibit Switch located on the circuit card installed in the
main bay to the UP position momentarily and then leave the switch in the middle
(OFF) position.
5) Remove the top and front panels to access the circuit cards at the bottom of the
distribution cabinet.
6) Carefully label the connectors plugged into the circuit card. These connectors
must be plugged into the same connectors on the replacement circuit card.
Refer to Figure 4-14 or Figure 4-15.
7) Unplug all connectors plugged into the circuit card.
8) Remove the screws securing the circuit card and remove the circuit card from the
distribution cabinet.
9) Slide the replacement circuit card into the mounting position inside the
distribution cabinet, and secure with the screws removed from the old circuit
card.
10) Ensure that the LVD Inhibit Switch is in the middle (OFF) position.
11) Plug all connectors removed from the old circuit card into the same position on
the replacement circuit card.
12) Push the LVD Inhibit Switch to the down (ON) position.
13) Remove the grounding wrist strap.
14) Reinstall the top and front panels that cover the circuit cards at the bottom of the
distribution cabinet.
15) Close the distribution cabinet’s front door. Turn the latch clockwise to secure the
door.
16) Enable the external alarms, or notify appropriate personnel that this procedure is
finished.
17) Ensure that there are no local or remote alarms active on the system.