Sun Microsystems SPARCstation 2 Service Manual page 100

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To check for and eliminate other possible problems before you replace the main
logic board:
1. Read the parts of Chapter 3 about how to halt your system, tools needed,
removing expansion units, removing the system unit's cover and attaching
a wrist strap.
2. Check that the green LED at the front of the chassis is not lit.
3. Check that the fans are not running.
4. Check that the system's power cord remains connected to the system and
the wall outlet.
5. Connect a terminal to the system unit.
For details, see the SPARCstation 2 Installation Guide.
6. This enables you to view output of the POST test results as they are run.
7. Disconnect the graphics monitor and the Ethernet connectors.
8. Remove the SBus boards from the system.
To do this see "SBus Boards" earlier in this chapter.
9. Unplug the hard disk drives and the diskette drive from their data and
power cables.
See Figures 4-17 and 4-19 in this chapter for the location of the data and
power cables.
10. Make sure all SIMMs are correctly seated (see Figures 4-6 and 4-7 for the
location of the SIMM slots), all cables attached, and all chips on the main
logic board correctly seated in their sockets.
Note – Bank 0 must be filled with SIMMs or the system will not pass its power-
on self test.
11. Turn the system power on.
12. Measure the power supply voltages with a VOM (Figure 4-26).
Caution – Measuring voltages without connecting the DC cable to the main logic
board will result in inaccurate readings. Without load, the power supply will
not regulate.
SPARCstation 2 Field Service Manual—February 1991