Power Supply Test - Sun Microsystems SPARC classic Service Manual

2. Check that the system power cord is properly connected to the system rear panel
power receptacle and to the wall outlet.
3. Verify with a VOM that the wall outlet is supplying AC power to
the system.
4. Turn the system power switch on and observe the keyboard.
The LEDs on the keyboard should briefly light. You should hear a tone from the
keyboard.
If you hear no tone or see no lights on the keyboard, the system's power supply may
be defective. See Section 4.2.1 "Power Supply Test."
If you hear a tone and see lights on the keyboard, but the system still fails to
initialize, see Section 4.2.2 "System Board Test."
5. If the system power supply is internally fused, check the fuse.
The fuse could be blown. If the power supply is working, you should hear the fans
humming.
4.2.1

Power Supply Test

1. Use a VOM (Volt Ohmmeter) to check the power supply output voltages.
Place the VOM negative probe on one of the logic ground pins in the connector, and
test the +12V, –12V, and +5.1V power pins individually with the positive probe (pins
1 through 7). See
Note – The power supply connector (J1401 for SPARclassic and SPARCclassic X or
J1601 for SPARCstation LX) must remain connected to the system board.
2. Replace the power supply assembly if any of the voltages are not present.
See Section 8.1 "Power Supply."
.
FIGURE 4-1
Chapter 4 Troubleshooting Procedures 4-3