Sun Microsystems 1.0, Service Manual

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MLB Test
Observe the lights on the keyboard to determine whether the MLB is defective. Press
and hold the
Stop(L1)-d
keys. While holding the keys down, turn the system
power switch on, and watch the lights on the keyboard. The Caps Lock key on the
keyboard should flash on and off, indicating that the system is running the power on
self test (POST).
If a failure occurs during POST, one of the keyboard LEDs may be on, indicating a
failed system part. Table 3–2 lists and defines the keyboard LED states.
TABLE 3–2
Keyboard LED States
LED State Description
Caps Lock is flashing POST is running
Num Lock is ON MLB fails
Scroll Lock is ON MBus module in slot 0 fails
Compose is ON DSIMM in slot J0201 fails
If a failure code appears, replace the defective part indicated by the LEDs. The POST
failed if the Caps Lock key fails to flash on and off after you have pressed and held
the
Stop(L1)-d
keys. The most probable cause of this type of failure is the MBus
module. Other optional parts in the system could cause POST to fail this way.
Remove any optional SBus cards and memory and run the test again before replacing
the MLB or MBus module. The system requires only that the MBus module 0,
DSIMM J0201, the MLB, the power supply assembly, and the keyboard are installed.
Remove the other parts and test the system again to eliminate the possibility that
optional parts are causing a failure. To receive additional POST failure information,
connect a terminal to serial port A on the SPARCstation 10 system.
26
SPARCstation 10 Service Manual
♦
Revision A, July 1993