Date Code 20011205
Installation
2-11
SEL-311B Instruction Manual
C
IRCUIT
B
OARD
C
ONNECTIONS
Accessing the Relay Circuit Boards
To change circuit board jumpers or replace the clock battery, refer to Figure 2.8 and take the
following steps:
1. Deenergize the relay.
2. Remove any cables connected to serial ports on the front and rear panels.
3. Loosen the six front-panel screws (they remain attached to the front panel), and remove the
relay front panel.
CAUTION
!
The relay contains devices sensitive to Electrostatic Discharge (ESD).
When working on the relay with front or top cover removed, work
surfaces and personnel must be properly grounded or equipment
damage may result.
DANGER
!
Removal of this front panel exposes circuitry which may cause
electrical shock that can result in injury or death.
4. Disconnect circuit board cables as necessary to allow the main board and drawout tray to be
removed. Ribbon cables can be removed by pushing the extraction ears away from the
connector. The 6-conductor power cable can be removed by grasping the power connector
wires and pulling away from the circuit board.
5. Grasp the drawout assembly of the main board and pull the assembly from the relay chassis.
6. Locate the jumper(s) or battery to be changed (refer to Figure 2.8). Make the desired
changes. Note that the output contact jumpers are soldered in place.
7. When finished, slide the drawout assembly into the relay chassis. Reconnect the cables
removed in step 4. Replace the relay front-panel cover.
8. Replace any cables previously connected to serial ports.
9. Reenergize the relay.
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