Theory of Operation
3-4
371B Service Manual
Acquisition circuit
Display counter circuit
Display digital to analog (D/A) converter circuit
Display select circuit
Cathode-Ray Tube (CRT) output circuit
High voltage power supply circuit
The horizontal sense circuit senses and amplifies the voltage between the
collector and emitter (or base and emitter) of the DUT. The vertical sense circuit
senses and amplifies the collector current of the device under test. The display
offset circuit determines the polarity of the output signals from these circuits
according to whether PNP or NPN is selected for collector supply, then sends
them to the display select and acquisition circuits.
The analog signal sent to the acquisition circuit is converted to a digital signal
and stored in memory in the acquisition circuit. The stored data are processed by
the CPU, then set to the display memory in the display counter circuit. Next,
they are reconverted to an analog signal in the display D/A converter circuit.
In non store mode, the display select circuit selects the signal from the display
offset circuit and sends it to the CRT output circuit. In store mode, the signal
from the display D/A converter circuit is selected and output to the CRT output
circuit.
This group of circuitry consists of circuits that control the 371B and circuits that
process acquired data. These circuits are:
CPU circuit
Front panel circuit
Floppy disk drive (FDD) interface circuit
The CPU circuit controls all operations of the 371B: such as, collector supply
and step generator control, sense circuit control, CRT display control, front panel
control, and floppy disk control. The CPU circuit also processes the data
acquired from the DUT. These operations are controlled by the microprocessor
and its operation programs through its address, data, and control bus lines.
The front panel circuit reads keys, switches, and rotary encoder information to
set the 371B to the desired measurement conditions. This circuit also displays
these settings to the operator by LED and numerical displays.
The floppy disk circuit stores data acquired from the DUT and 371B setting
information. The data and information are stored on a 3.5-inch floppy disk.
Control and Processing
Summary of Contents for 371B
Page 4: ......
Page 14: ...Service Safety Summary 371B Service Manual...
Page 18: ...Preface 371B Service Manual...
Page 21: ...Specifications...
Page 22: ......
Page 24: ...Product Overview 371B Service Manual...
Page 38: ...Specifications 371B Service Manual...
Page 39: ...General Information...
Page 40: ......
Page 58: ...General Information 371B Service Manual...
Page 59: ...Theory of Operation...
Page 60: ......
Page 62: ...Theory of Operation 3 2 371B Service Manual Figure 3 1 371B Block Diagram...
Page 71: ...Maintenance...
Page 72: ......
Page 101: ...Performance Verification...
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Page 220: ...Performance Verification 371B Service Manual...
Page 221: ...Options...
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Page 226: ...Options and Accessories 371B Service Manual...
Page 227: ...Electrical Parts List...
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Page 235: ...Diagrams...
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Page 237: ...8 1 371B Service Manual Circuit Board Interconnections 2 2...
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Page 239: ...8 3 371B Service Manual Circuit Board Interconnections 2 2...
Page 240: ...371B Service Manual...
Page 241: ...8 5 371B Service Manual Test Point Adjustment Locations 1...
Page 242: ...8 6 371B Service Manual Test Point Adjustment Locations 2...
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Page 245: ...8 9 371B Service Manual Troubleshooting Tree...
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Page 247: ...8 11 371B Service Manual Troubleshooting Tree Cont...
Page 248: ...371B Service Manual...
Page 249: ...Mechanical Parts List...
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Page 259: ...9 9 371B Service Manual Figure 9 1 Cabinet Rear 97 96 68...
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Page 261: ...9 11 371B Service Manual Figure 9 2 Display Front 73...
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Page 267: ...9 17 371B Service Manual Figure 9 3 Chassis Ciircuit Board...
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Page 269: ...9 19 371B Service Manual Figure 9 4 Power Supply...
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Page 276: ...Mechanical Parts List 371B Service Manual...
Page 277: ...9 27 371B Service Manual Figure 9 5 Test Fixture 78 78 REV MAR 96 75 72...
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Page 279: ...9 29 371B Service Manual Figure 9 6 Front Porch...
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