Sun Microsystems SPARCclassic Service Manual page 137

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.
To replace a DSIMM:
1. Identify and remove the faulty DSIMM.
See "Removing a DSIMM" on page 120. Make sure you use the wrist strap and
antistatic mat. For any DSIMM you remove, be sure to note its original slot.
2. Remove the replacement DSIMM from its protective packaging, and place it on
the antistatic mat.
3. Determine where to install the new DSIMM and any others you may have
removed.
The replacement DSIMM should go where the faulty DSIMM was located. Any
other DSIMMs you removed should go in the slots where they were originally
installed.
Note - The six DSIMM slots are logically grouped into pairs—labeled 1, 2, and 3.
When installing DSIMMs, you must make sure that each pair of DSIMM slots is
identically configured. For more information, see the discussion of paired
DSIMMs in "DRAM Single In-line Memory Modules (DSIMMs)" on page 117.
4. Install the DSIMMs.
Since the DSIMMs are closely spaced, they must be installed in the proper order.
Start with the slot closest to the center of the main logic board and work outward
toward the board's front edge.
Hold each DSIMM at its edges and insert it into the plastic guides at an angle
about 30 degrees from the vertical position (see Figure 11–11). Then, by pushing
gently on its top edge, rotate the DSIMM into an upright position. You should
hear it click into place.
Note -
Each DSIMM is keyed so it can only be installed in one way.
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