Service manual

Troubleshooting 25
3
Troubleshooting
Introduction
Shock Hazard: Most of the procedures in this chapter must be performed with power applied and
protective covers removed. These procedures should be done only by trained service personnel aware of
the hazard from electrical shock.
This instrument uses components that can be damaged or suffer serious performance degradation due to
ESD (electrostatic discharge). Observe standard antistatic precautions to avoid damage to the
components (see Chapter 1).
This chapter provides troubleshooting and repair information for the power supply. Before beginning troubleshooting
procedures, make certain the problem is in the power supply and not with an associated circuit, the GPIB controller (for
GPIB system power supplies), or ac input line. Without removing the covers, you can use the Verification tests in Chapter 2
to determine if the power supply is operating normally.
The information in this chapter is organized as follows:
Topic Information Given
Test Equipment Required Equipment required for completing all the tests in this chapter.
Troubleshooting Procedures An explanation of the error codes and messages generated during the power-on selftest.
A series of flow charts for systematic location of defective boards, circuits, and
components.
Post-Repair Adjustments Calibration and EEPROM initialization procedures required after the replacement of
certain critical components.
Disassembly Procedures Gaining access to and/or replacing components.
Test Equipment Required
Table 3-1. Test Equipment Required
Equipment Purpose Recommended Model
Test Clips To gain access to IC pins. AP Products No. LTC
Ammeter/Current Shunt To measure output current. Agilent 6690A: Burster 1280
Agilent 6691A, 6692A: Guildline 9230/300
Oscilloscope To check waveforms and signal levels. Agilent 54504A
GPIB Controller To communicate with power supply
via the GPIB (for system units).
Agilent BASIC series
DC Voltmeter To measure output voltage and
current, bias and references.
Agilent 3458A