Service manual

PN 4237242C
4.6-2
SERVICE AND REPAIR PROCEDURES
AT MOTHERBOARD
6. Disconnect the floppy disk drive, the external interface cables and the speaker:
r Floppy disk drive connects to J17.
r Serial 1 port connects to J15.
r Serial 2 port connects to J14.
r Parallel (Printer) port connects to J18.
r Speaker port connects to J22.
7. Remove the two motherboard ground screws (Figure 4.6-2).
8. Remove the nylon retaining posts (Figure 4.6-1):
a. Start at one end and work to the other.
b. Squeeze the nylon retaining posts while lifting the AT motherboard, until the card
can be completely removed.
Installation
1. Press the new motherboard onto the nylon retaining posts and attach the two ground
screws.
2. Verify the proper switch and jumper settings (Figure 4.6-2).
3. Verify that the SIMM memory is in place and properly seated (Figure 4.6-1).
4. Connect the external interface cables, the speaker and the floppy disk drive
(Figure 4.6-2):
r Serial 1 port connects to J15.
r Serial 2 port connects to J14.
r Parallel (Printer) port connects to J18.
r Speaker port connects to J22.
r Floppy disk drive connects to J17.
5. Connect P4 and P5 of the AT power supply to J8 and J9 on the motherboard.
6. Install the SPAD (Heading 4.7), URA (Heading 4.8) and both DRA (Heading 4.9) cards.
7. Replace the top cover.
8. Reconnect the ac power cable.
CAUTION
Risk of electronic damage. If connectors P4 and P5 are attached incorrectly, the motherboard will
be damaged. They can only be installed correctly one way. They are, however, identical and could easily be
switched. To ensure that P4 and P5 are installed correctly, attach them so that the black wires from each
connector are situated together in the middle.