Caps Lock Key Fails To Flash During The Post - Sun Microsystems SPARCstation 20 Service Manual

1. Connect a terminal to serial port A or use a tip connection to another workstation
to receive additional POST failure information.
See "Setting Up a tip Connection" on page 19.
2. Press and hold the keyboard Stop (L1) and D keys. While holding the keys
down, turn the system power switch on. Release the keys. Watch the keyboard
LEDs.
The Caps Lock key on the keyboard should flash, indicating that the system is
executing the POST.
If the Caps Lock key fails to flash after the keyboard Stop (L1) and D keys
have pressed and held, POST failed. MBus module 0 or the system board may be
defective.
To further troubleshoot the system board, see "Caps Lock Key Fails to Flash
During the POST" on page 32.
3. Observe the keyboard LEDs.
If a failure occurs during POST, an LED may light up.
describes types of problems that occur when an LED on the keyboard lights up.
4. Observe serial port A diagnostic information.
This may provide additional failure information.
5. Replace the defective part indicated.

Caps Lock Key Fails to Flash During the POST

If the Caps Lock key fails to flash during the POST:
1. Remove optional SBus cards and all NVSIMMs, VSIMMs, and DSIMMs (except
J0201, which is required).
2. Initiate POST again with only: an MBus module in slot 0, a DSIMM in slot J0201,
the power supply assembly, and the keyboard installed.
3. Observe serial port A diagnostic information. This may provide additional failure
information.
4. Replace the defective part indicated.
5. If POST passes with the optional parts removed, install the optional parts one at
a time. Initiate POST after each optional part is installed; observe the diagnostic
output on serial port A and the keyboard LEDs.
32 SPARCstation 20 Service Manual • July 1996
in Chapter 3
TABLE 3-1