Keithley 2430 User Manual

4-6 Troubleshooting
Analog circuits
Figure 4-2 shows a block diagram of the analog circuits.
D/A converters control the programmed voltage and current, or voltage compliance and current
compliance. Each DAC has two ranges, a 10V full-scale output or a 1V full-scale output. The
DAC outputs are fed to the summing node, FB. Either the V DAC or the I DAC has the ability to
control the main loop. If the unit is set for SV (source voltage), it will source voltage until the com
-
pliance current is reached (as determined by the I DAC setting), and the current loop will override
the voltage loop. If, however, the unit is set for SI (source current), it will source current until the
compliance voltage is reached (as determined by the V DAC setting), and the voltage loop will
override the current loop. A priority bit in the Vclamp/I clamp circuit controls these functions.
The error amplifier adds open-loop gain and slew-rate control to the system to assure accu-
racy and provide a controllable signal for the output stage, which provides the necessary voltage
and current gain to drive the output. Sense resistors in the HI output lead provide output current
sensing, and a separate sense resistor is used for each current range. The 1A and 3A ranges use
0.2V full-scale for a full-range output, while all other ranges use 2V output for full-scale current.
Voltage feedback is routed either internally or externally.
V DAC
I DAC
Control
O
+
-
V Clamp
I Clamp
Error
Amp
Output
Stage
Sense
Resistors
FB
VFB
IFB
VFB
IFB
MUX
+7
S
A/D
-150
-42
+42
+150
Output
HI
S+
O
Output
LO
S-
O
Remote
Protection
Protection
Guard
Out
Guard
Sense
Figure 4-2
Analog circuitry block diagram
There are four voltage ranges: 0.2V, 2V, 20V, and 100V. The feedback gain changes only for
the 20V and 100V ranges, resulting in three unique feedback gain values. A multiplexer directs
the voltage feedback, current feedback, reference, or ground signal to the A/D converter. An
opto-isolated interface provides control signals for both DACs, analog circuit control, and A/D
converter communication to the digital section.

Keithley 2430 Specifications

General

Type	Source Measure Unit (SMU)
Current Range	0 to 1 A
Digital I/O	Yes
Resolution (Voltage)	100 nV
Resolution (Current)	10 pA
Display	LCD
Interface	GPIB, USB, Ethernet
Voltage Resolution	100 nV
Current Resolution	10 pA
Display Type	LCD

Summary

Warranty Information

Manual Print History

Safety Precautions

Types of Product Users

Defines roles for responsible body, operators, and service personnel.

General Safety Precautions

Essential advice for safe operation and preventing electrical shock.

Performance Verification

Introduction to Performance Verification

Purpose and scope of verification tests for instrument accuracy.

Verification Test Requirements

Conditions and preparations needed for accurate verification tests.

Environmental and Warm-up Conditions

Specifies ambient conditions and instrument warm-up duration.

Recommended Test Equipment

Lists necessary external instruments for performing verification tests.

Restoring Factory Defaults

Resets instrument settings to factory default configuration.

Performing Verification Procedures

Step-by-step guide for conducting all performance verification tests.

Setting Source and Measurement Ranges

Procedures for configuring source and measurement range settings.

Compliance Considerations

Explanation of output clamping behavior and compliance limits.

Output Voltage Accuracy Verification

Method to check the precision of the instrument's voltage output.

Output Current Accuracy Verification

Method to check the precision of the instrument's current output.

Resistance Measurement Accuracy

Procedure to verify the accuracy of resistance measurements.

Calibration Procedures

Introduction to Calibration

Purpose and methods for maintaining instrument accuracy through calibration.

Calibration Cycle and Equipment

Recommended frequency for calibration and required equipment.

Unlocking and Performing Calibration

Steps to enable calibration mode and perform front-panel calibration.

Password Management and Error Handling

Procedures for changing/resetting passwords and understanding errors.

Routine Maintenance

Introduction to Routine Maintenance

Overview of tasks for regular instrument upkeep.

Line Fuse Replacement

Procedure for safely replacing the main power line fuse.

Troubleshooting Guide

Introduction to Troubleshooting

Purpose and scope of the troubleshooting section.

Safety and Repair Considerations

Critical safety advice and important points before making repairs.

Front Panel and Operational Tests

Tests to verify front panel and operational system functionality.

Principles of Operation

Explanations of system components and their functions for diagnosis.

Circuit-Specific Checks

Diagnostic steps for display, power supply, digital, and analog circuits.

Battery Replacement Procedure

Procedure for replacing the internal backup battery.

Instrument Disassembly

Introduction to Disassembly

Overview of handling, cleaning, and instrument disassembly.

Handling Static Sensitive Devices

Precautions for handling components sensitive to electrostatic discharge.

Case Cover and Board Removal

Steps to remove the outer casing and internal circuit boards.

Replaceable Parts Information

Introduction to Parts Lists

Purpose of the replaceable parts section.

Ordering and Service Information

Details on how to order parts and information on factory service.

Instrument Specifications

Accuracy Calculation Methods

How to calculate measurement and source accuracy for the instrument.

Command Reference

Introduction to Command Reference

Overview of the remote calibration commands and error detection methods.

Command Summary

A comprehensive list of available remote commands.

Calibration Programs

Introduction to Calibration Programs

Purpose of the appendix and its BASIC calibration programs.

Hardware and Software Requirements

Necessary computer hardware and software for running calibration programs.

General Program Instructions

Steps for setting up and executing the calibration programs.