GE DigitalFlow GF868, Руководство по обслуживанию

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DigitalFlow™ GS868 Service Manual 33
Chapter 4. Parts Replacement
4.2 Removing the Printed Circuit Board
All of the remaining procedures require removal of the printed circuit board. To accomplish this task, refer to Figure 8
on page 39 and Figure 9 on page 40 while completing the following steps:
1. Remove the main power to the electronics console.
2. Open the electronics console. For LVD compliant units, remove the two mounting screws and lift the clear plastic
shroud out of the electronics console. Remove the six mounting screws and lift the main aluminum shroud out of
the electronics console.
3. Disconnect the main power leads and the PC board ground wire from terminal block
TB1
on the printed circuit
board. Remove the electrical connectors from all installed option cards and terminal blocks. Disconnect the
twisted-pair display backlight cable from connector
J2
on the left side of the PC board.
4. Using a 3/8 in. nutdriver or open-end wrench, remove the three short standoffs along the left side of the main
circuit board and the three long standoffs along the right side of the main circuit board.
5. While supporting the printed circuit board, remove the two screws or standoffs along the bottom edge of the
printed circuit board.
Note:
For an LVD compliant meter with the clear plastic shroud over the electrical connectors, there will be
standoffs in these two locations. For meters not equipped with this shroud, there will be Phillips head screws in
these two locations.
6. Carefully list the printed circuit board out of the enclosure. Continue to support the printed circuit board, as the
keypad and display cables are still connected to the rear of the board.
7. Tilt the top of the printed circuit board forward, and mark the top edges of the two ribbon-cable connectors. Then,
remove these cables from their connectors on the rear of the board.
8. The printed circuit board is now free and may be removed to a clean work area.
If the printed circuit board is being replaced, proceed to the section on Installing the Printed Circuit Board (page 37)
now. Otherwise, refer to the appropriate section for instructions on Installing an Option Card (page 35) , Replacing the
EPROM (below) or Replacing the LCD Display (page 36).
WARNING! The main power to the Model GS868 must be disconnected before proceeding.
CAUTION! Be very careful not to damage the vertical components along the top edge of
the printed circuit board (see Figure 9 on page 40). Severe or repeated bending
of these components will break their leads.