Sun Microsystems SPARC classic Service Manual page 147

Note – Removing and replacing the main logic board is a drastic step to take. See
Section 11.4.2 "Before Replacing the Main Logic Board" on page 11-21 for
troubleshooting information.
To remove the main logic board:
1. Prepare to work on the system as described in Chapter 6 "Power Off and On," and
in Chapter 7 "Internal Access."
Halt the system and verify that the power LED is not lit and that the fan is not
running. Then open the system unit, detach all peripherals, and attach a wrist strap
as described in Section 7.3 "Attaching the Wrist Strap" on page 7-3.
Caution – The AC power cord should remain attached between the system unit and
an AC wall outlet. This connection provides the ground path necessary to protect
internal system components from harmful static discharges. Inside the system unit,
be sure the power supply wiring harness is connected to the main logic board to
complete the ground.
Caution – Verify that the system power switch is in the Standby position. The green
LED at the front of the system unit should not be lit and the fan should not be
running. When the system power switch is in the Standby position, and the AC
power cord remains connected to a power outlet, hazardous AC voltage is still
present in the power supply primary. Do not attempt to service the power supply
under these conditions. Disconnect the AC power cord prior to handling the power
supply. When servicing any other system component, the AC power cord should
remain connected and poses no safety hazard.
2. Place an antistatic mat, shiny side down, next to the system unit.
3. Remove any SBus cards.
See Section 11.1 "SBus Cards" on page 11-1 for removal procedures.
4. Remove all DSIMMs from the main logic board.
Note carefully the slot where each DSIMM resides so it may be installed in the same
slot on the replacement main logic board. See Section 11.3.2 "Removing a DSIMM"
on page 11-13, for removal procedures.
5. Remove the optional VSIMM (if present).
See Section 11.2.1 "Removing the VSIMM" on page 11-7, for removal procedures.
Chapter 11 Main Logic Board and Component Replacement 11-25