Maintenance and Repair
4. Unplug all interconnect ribbon cables from the digital assembly and position them out
of the way.
5. Remove the four digital assembly mounting screws and lock washers, located near
the four corners of the board, using a #2 Phillips screwdriver.
6. Remove the digital assembly.
10 Digital Assembly Installation
1. Position the digital assembly into the chassis and align the four mounting holes with
the threaded standoffs in the bottom plate.
2. Install the four digital assembly mounting screws and lock washers, located near the
four corners of the board, using a #2 Phillips screwdriver. Tighten to 6 in-lb torque.
3. Plug all interconnect ribbon cables into the digital assembly. Ensure proper polarity,
with Pin 1 (the edge of the cable with a brown wire) as marked on the board. See
Figure 9-5.
4. Plug the USB cable into the connector on the rear underside of the digital board.
5. If a GPIB interface is installed: Plug the GPIB interface board into the GPIB header
on the digital assembly. Using a #2 Phillips screwdriver, install the screw that holds
the board in place. See Figure 9-5.
6. Follow Procedure 2 for Top Cover Installation.
11 Encoder Removal
1. Follow Procedure 1 for Top Cover Removal.
2. Using a 5/64″ hex driver, loosen the setscrew in the side of the ENCODER knob and
remove the knob.
3. Remove the encoder connector from the rear of the ENCODER. See Figure 9-5.
4. Remove the nut from the front of the ENCODER by using a deep 1/2″ socket.
5. Remove the ENCODER from the panel.
12 Encoder Installation
1. Install the ENCODER from the rear of the front panel, and orient it so that the
connector is toward the top of the Model 1140A. See Figure 9-5.
2. Install the nut on the threads of the ENCODER. Take care not to cross-thread the nut as
the threads of the ENCODER are plastic.
3. Tighten the encoder nut with a 1/2″ socket to 3.0 in-lb torque.
4. Install the encoder connector on the rear of the ENCODER. Ensure proper polarity,
with Pin 1 (the edge of the cable with a brown wire) of the cable toward the left side
of the unit.
5. Install the knob on the front panel using a 5/64″ hex driver. Tighten to 6 in-lb torque.
6. Verify that the ENCODER operates freely by turning and pushing it.
7. Follow Procedure 2 for Top Cover Installation.
9-8
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