User Manuals: HP 428B Clip-On DC Milliammeter

Manuals and User Guides for HP 428B Clip-On DC Milliammeter. We have 1 HP 428B Clip-On DC Milliammeter manual available for free PDF download: Operating And Service Manual

HP 428B Operating And Service Manual (52 pages)

Brand: HP | Category: Measuring Instruments | Size: 4.67 MB

Table of Contents
6
Table 1-1 Specifications
8
General Information
9
Introduction
9
Instrument and Manual Identification
9
Figure 1-1. Model 428B Clip-On Milliammeter
9
Installation
10
Unpacking and Mechanical Inspection
10
Operation Check
10
Power Requirements
10
Operation on 115 or 230 Volts
10
Three Conductor Power Cable
10
Rack Mount Model
10
Preparation for Storage and Shipment
10
2·20. Storage
10
Figure 3-1. Measurement Procedures
11
Operating Instructions
12
Introduction
12
Operating Precautions
12
Operating Considerations
12
Interchanging Probe Heads
12
Effect of Measurement on Circuit
12
Effect of Circuit on Measurement
12
Magnetic Fields
13
Operating Practices
13
Mechanical Operation of Probe
13
Degaussing of Probe Head
13
Electrical Zero Set
13
Polarity of Current
13
Figure 3-2. Polarity of Current
13
Increasing the Absolute Sensitivity
14
Current Check Loops
14
Nulling Currents
14
Use of Output Jack
14
With Oscilloscope
14
With Recorder
14
Figure 3-3. Increasing the Absolute Sensitivity
14
Figure 4-1. Block Diagram
15
Theory of Operation
16
Introduction
16
Current Probe
16
Figure 4-2. Simplified Block
16
Figure 4-3. Magnetic Mechanical Analogy
17
Figure 4-5. 428B Flux Gate
17
Figure 4-4. Basic Flux Gate
17
Figure 4-6. Waveforms
17
20 Khz OSCILLATOR
18
Head-Drive Amplifier
18
Detector Gate Amplifier
18
40 Khz INPUT/AMPLIFIER CIRCUIT
18
Synchronous Detector and Filter (C24)
18
Figure 4-7. Detector Bridge
18
DC Amplifier
19
Negative Feedback Current Circuit
19
40 Khz PHASE SHIFTER
19
Power Supply
19
Figure 4-8. Negative Feedback
19
Figure 4-9. 90° Phase Shift
19
Table 5-1. Recommended Test Equipment
20
Maintenance
21
Introduction
21
Test Equipment Required
21
In-Cabinet Performance Checks
21
Cleaning of Probe Jaws
21
Electrical Zero Set
21
Figure 5-1. Cleaning Probe Jaws
21
Figure 5-2. Electrical Zero Set
21
Range Check
22
Meter Tracking
22
Output Calibration
22
Frequency Response
22
Figure 5-3. Range Check
22
Ac Overload
23
Noise Check
23
Adjustment Procedure
23
Power Supply
23
Mechanical Zero Set
23
DC Amplifier Balance
23
Figure 5-4. AC Overload
23
Alignment
24
Oscillator Balance
24
Oscillator Frequency
24
Oscillator Level
24
Detector Gate
24
Tuned Amplifier
24
Equipment Setup
24
Input Alignment
24
Interstage Alignment
24
Detector Phase Adjustment
24
Preliminary Adjustment
25
Preset the Controls as Follows
25
Drive Balance Adjustment
25
Figure 5-7. Detector Phase Display
25
Troubleshooting
26
Front Panel Troubleshooting
26
Detailed Troubleshooting
26
Probe Check
26
Power Supply Check
26
Figure 5-9. Detailed Troubleshooting Tree
27
Oscillator - Buffer Amp. Check
28
Synchronous Detector
28
Replaceable Parts
30
Introduction
30
Ordering Information
30
Non-Listed Parts
30
Table 6-1. Replaceable Parts
31
Figure 6-1. Parts Breakdown, Current Probe
35
Circuit Diagrams
36
Introduction
36
Block Diagram
36
Schematic Diagrams
36
Component Location Diagrams
36
Figure 7-1. Block Diagram
37
Figure 7-2. Component Locator for Circuit Board Part
38
Figure 7-3. Front Panel Component Locator
38
Figure 7-4 Rear Panel Component Locator
38
Figure 7-5. Power Supply
39
Figure 7-6. Block Diagram
40
Figure 7-7. Component Locator for Circuit Board Part
41
Figure 7-8. Front Panel Component Locator
41
Figure 7-9 Rear Panel Component Locator
41
Figure 7-10. Metering Circuit
42
Manual Backdating Changes
43
Figure A-1. 428B Side Views
44
Figure A-2 Backdating Schematics for 428B
45
Figure A-3 Backdating Schematics for 428B
46

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HP 428B Operating And Service Manual (52 pages)

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