Appendix B. Optional Enclosures
B-5
DigitalFlow™ GC868 Service Manual (1 and 2-Channel)
B.7 Rack Mount
Printed Circuit
Board
Replacement
If troubleshooting procedures have indicated a defective printed circuit board, follow
the instructions in this section to replace the defective board with a new one.
B.7.1 Circuit Board
Removal
Refer to Figure B-2 on page B-9 and complete the following steps:
1.
After disconnecting the main power to the meter, remove the top panel from the
enclosure by removing the four screws indicated.
2. Disconnect all external option card connectors at the rear panel of the meter.
Then, remove all installed option cards from the printed circuit board, as
described earlier in this chapter.
3. Disconnect the main POWER LEADS from the screw terminals at the rear of the
printed circuit board. Make a sketch of the terminal block and the locations of
the black, white and green power leads to assist in reinstallation of the new cir-
cuit board.
4. Remove the RS232, ANALOG OUT and TRANSDUCER connectors from the printed
circuit board. Use a marker to identify pin #1 on the right side (keypad side) of
these connectors.
Note:
These connectors should be pulled straight up and off the printed circuit
board.
DO NOT
remove the leads from the screw terminals.
5. Remove the flat KEYPAD CABLE connector from terminal J50 near the front of the
printed circuit board. Mark pin #1 of the cable connector, which is located nearer
the rear of the enclosure.
6. Disconnect the twisted-pair DISPLAY BACKLIGHT cable from connector J2
beneath the left side of the printed circuit board. Although this connector is
polarized, it will help to note that the red wire is closer to the rear of the enclo-
sure.
7. Remove the flat LCD DISPLAY CABLE connector from terminal J52 near the option
card sockets. Mark pin #1 of the cable connector, which is located nearer the
front of the enclosure.
8. Using a slotted screwdriver, remove the three mounting screws along each side
of the printed circuit board. Carefully lift the printed circuit board out of the
enclosure.
Proceed to the next section for instructions on installing the new printed circuit
board.
WARNING! The main power to the Model GC868 must be
disconnected before proceeding.