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6.
Remove the temperature sensor wires from the plus and minus binding posts by
grasping the heat-shrink tubing of the temperature sensor wires and gently pulling
straight back to remove the sensor from each binding post. See Figure 9-8.
Note: The RTV adhesive holding the temperature sensors in the binding posts will
break as each sensor is removed.
7.
Unsolder the two pairs of black and red wires from the binding post printed circuit
board. See Figure 9-8.
8.
Remove the four front-panel mounting nuts and lock washers, located near the four
corners of the front panel, using a 5/16" socket with a 6" extension.
9.
Pull the front-panel assembly forward to clear the thermocouple connector. This will
allow access to the two green guard wires on the binding post printed circuit board.
10.
Unsolder these green wires from the binding post printed circuit board.
11.
Carefully remove the front panel.
22
Front-panel Assembly Installation
1.
Position the front panel in front of the Model 1140A.
2.
Solder the two green guard wires onto the holes near the bottom of the binding post
printed circuit board. Either wire may go in either hole.
3.
Install the four front-panel mounting nuts and lock washers, located near the four
corners of the front panel, using a 5/16" socket with a 6" extension.
4.
Solder the black and red twisted wires from the analog assembly to the binding post
printed circuit board. The red wire goes into the top open hole on the side toward the
display, the black wire into the open hole directly below the red wire. See Figure
9-10.
5.
Similarly, solder the black and red twisted wires from the TC connector assembly to
the binding post printed circuit board. The red wire goes into the top open hole, the
black wire into the lower open hole. See Figure 9-10.
6.
Install the negative temperature sensor wire (soldered to Positions 3 and 7 on the
analog board) into the hole in the rear of the negative (lower) binding post. Be sure to
insert it all the way so that it bottoms in the hole. Note that there is a small amount of
thermally conductive compound inside the hole. See Figure 9-8.
7.
Similarly, install the positive temperature sensor wire (soldered to Positions 1 and 5
on the analog board) into the hole in the rear of the positive (upper) binding post. Be
sure to insert it all the way so that it bottoms in the hole. Note that there is a small
amount of thermally conductive compound inside the hole. See Figure 9-8.
8.
Apply a small amount of RTV adhesive to the sensor wires at the point where they
exit from holes in the binding posts. This retains the sensors in the binding posts.
9.
Install the display connector to the rear of the LCD display assembly. Ensure proper
polarity, with Pin 1 (the edge of the cable with a brown wire) of the cable toward the
top side of the unit. See Figure 9-5.
9-15
Maintenance and Repair
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