Sun Microsystems SPARC classic X, Service Manual

Page: 144 / 198

11-22 SPARCclassic/SPARCclassic X/SPARCstation LX Service Manual • November 1993
Note –
Removing and replacing the main logic board is a drastic step to take.
Therefore, it is important to try to troubleshoot all other possibilities before
removing and replacing the main logic board.
To check for and eliminate other possible problems before you replace the main logic
board, do the following:
1. Preparation.
a. Follow the instructions in Chapter 6 “Power Off and On,” and in Chapter 7
“Internal Access,” about halting your system, opening the system unit, and
attaching a wrist strap. The wrist strap should be attached to the metal casing
of the power supply inside the system unit.
b. Make sure that the system unit’s power is in the Standby position by verifying
that the green LED at the front of the chassis is not lit and that the fan in the
power supply is not running. The AC power cord should remain attached to the
system unit and AC wall outlet. Inside the system unit, the power supply wiring
harness should remain connected to the main logic board to complete the ground.
c. Attach a terminal to serial port A on the system unit. For details, see the
Desktop SPARC Hardware Owner’s Guide. A terminal enables you to view the
output of the POST results as they are run. Alternatively, you can set up a
tip
connection to another workstation; see Section 3.4.1 “Setting Up a
tip
Connection to Another Workstation” on page 3-5, for details.
d. Disconnect the video monitor, the keyboard, and the Ethernet cable from the
system unit.
e. Remove any SBus cards from the system. See Section 11.1 “SBus Cards” for
removal/replacement procedures.
f. Disconnect the hard disk drive and the diskette drive from their power and
data cables. See
FIGURE 9-12
on page 9-17 and
FIGURE 9-13
on page 9-18 for cable
locations.
2. Verify the connections of internal parts.
a. Make sure that all SIMMs are correctly seated, the power supply harness is
connected to the main logic board, and all replaceable chips on the board are
correctly seated in their sockets. (See
FIGURE 11-12
and
FIGURE 11-13
for SIMM
locations.)
b. Follow the directions in Chapter 6 “Power Off and On,” for turning on the
power.
c. Using a Volt-Ohmmeter (VOM), measure the power supply voltages at the 12-
pin power connector on the main logic board.