Chapter 5 Service
Troubleshooting Hints
102
Troubleshooting Hints
This section provides a brief check list of common failures. Before
troubleshooting or repairing the power supply, make sure that the failure is in
the instrument rather than any external connections. Also make sure that the
instrument is accurately calibrated. The power supply’s circuits allow
troubleshooting and repair with basic equipment such as a digital multimeter
and a 100 MHz oscilloscope.
Caution This instrument contains CMOS integrated circuits which are susceptible to failure
due to electrostatic discharge. Refer to the ‘‘Electrostatic Discharge (ESD)
Precautions’’ section earlier in this chapter for further handling precautions.
Unit is Inoperative
Verify that the ac power cord is connected to the power supply.
Verify that the front-panel power switch is depressed.
Verify that the power-line fuse is installed:
Use the 6.3 AT, 250 V fuse for 100 or 115 Vac operation.
Use the 3.15 AT, 250 V fuse for 230 Vac operation.
Verify the power-line voltage setting.
See ‘‘To prepare the power supply for use’’ on page 23.
Unit Reports Errors 740 to 750
These errors may be produced if you accidentally turn off power of the unit
during a calibration or while changing a non-volatile state of the instrument.
Recalibration or resetting the state should clear the error. If the error persists,
a hardware failure may have occurred.
Unit Fails Self-Test
Verify that the correct power-line voltage setting is selected. Also, ensure that
all terminal connections are removed while the self-test is performed. Failure
of the DAC U22 on the PC board will cause many self-test failures.
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