Sun Microsystems SPARCstation 20, Service Manual

Page: 120 / 266

96 SPARCstation 20 Service Manual • July 1996
Installing the SCSI Data Cable (SunCD 4 Drive-
Type Chassis)
Caution – Use proper ESD grounding techniques when handling components. Wear
an antistatic wrist strap and use an ESD-protected mat. Store ESD-sensitive
components in antistatic bags before placing it on any surface.
Note –
The SCSI data cable is a three-connector pigtail cable with colored tape that
joins two of the cables closest to the P2 connector. Visual markers are placed on the
cables to aid cable alignment. When properly installed, the SCSI data cable P1
connector is connected to the SCSI backplane with the tape aligned between the card
guide plastic cable clips (see
FIGURE 8-38
). The SCSI data cable P3 connector is
connected to the system board and threaded through the chassis wall metal cable
guides. The SCSI data cable P2 connector is routed through the gap between the
hard disk drive and the chassis wall. P2 connects to the SunCD 4 drive (if installed),
or is secured under the chassis floor metal cable clips.
1. Secure the SCSI data cable under the plastic card guide cable clips.
Note –
The taped portion of the SCSI data cable should be positioned directly
between the plastic card guide cable clips as shown in
FIGURE 8-38
.
2. Connect the SCSI data cable to the SCSI backplane.
3. Connect the DC power harness to the SCSI backplane.
4. Insert the front edge of the system board into the card guide. Lift the rear of the
board slightly and slide it along the card guide until it is fully inserted
(
FIGURE 8-30
).
5. Connect the DC power cable, SCSI data cable, diskette data cable, and speaker/
LED cable to the system board.
Note –
Thread the SCSI data cable through the chassis wall metal cable clips after
the SCSI data cable is connected to the system board (
FIGURE 8-33
).
6. Replace the SBus card.
See “Installing an SBus Card” on page 156.
7. Tighten the two captive Phillips-head screws that secure the system board to the
chassis rear (
FIGURE 8-30
).