TM 5-3810-307-24-1-2
11. PROCEDURE 3B. MAIN BOARD 024-350-300-222 REPLACEMENT
Refer to Drawing 3B in Section 10, central unit parts list for board location.
NOTE
Mark all connections before removing, to identify location for
reconnecting.
1. Turn system power off.
2. Remove the central unit lid.
CAUTION
Take care not to damage the boards with the screw driver,
when removing and inserting screws.
NOTE
Use care when lifting the CPU module board and analog input
module from the main board, due to the fact that these boards
have pins on the bottom side which insert into the main board.
3. Remove CPU module board and EPROM module Items #20 and #21, see
Drawing 3B, by taking out the 4 small Philips screws holding them in place.
4. Disconnect ribbon cable #7 and #8, see Drawing 3B.
5. Disconnect connection X1:1 and X1:3, see Drawing 3B.
6. Remove the 9 main board mounting screws.
7. Take notice of the orientation of the main board in the central unit. Remove main
board and place in the packing material that the replacement main board came
in.
8. Carefully insert the new main board in place. see Drawing 3B.
9. Insert the main board mounting screws and washers.
10. Insert CPU module board by lining up the pins into the sockets on the main
board and the 4 screws holes.
11. Insert the 4 small Philips screws and washers.
12. Connect X1:1, X1:3 and ribbon cables #7 and #8, see Drawing 3B.
13. Inspect the gasket for nicks, cuts, or damages. Refer to 031-300-340-003 DS
350 Central Unit Gasket Recommendations and 031-300-340-002 Central Unit
Cover Installation and Tightening Procedure.
