Theory of Operation
3-6
371B Service Manual
Detailed Circuit Description
This section provides a detailed description of the electrical operation of the
371B. These descriptions, together with the troubleshooting/diagnostics
information provided in Chapter of Maintenance, and appropriate test equipment,
enable you to isolate a problem to the faulty component.
Schematic diagrams are provided in Chapter of: Diagrams and Circuit Board
Illustrations.
Digital Logic.
Digital logic techniques are used to perform logic functions within
electrical circuits. The functions and operations of the logic circuits are
represented by standard logic symbols and terms. Logic functions are described
using the positive logic convention. (Where voltages above the logic threshold
voltage are the true, or 1 state, and voltages below the threshold are the false, or
0 state.)
In logic descriptions the logic true state voltages are referred to as high and logic
false states are referred to as low.
. The specific voltages that constitute a high or low state vary between
different families of electronic devices (e.g.. ECL. CMOS, and TTL logic).
Active-low signals are indicated by an (L) following the signal name. Signal
names without indicators are considered to be either active-high or to have both
active high and active low states.
Assembly Numbers.
The following circuit descriptions are presented according to
their schematic number. For example, the A1 Mother Board, is discussed first
and the A2 MPU Board is discussed second. Its electrical circuits are shown on
the MPU schematic, and so on.
Schematic Standards.
Refer to Chapter of Diagrams and Component Location
Illustrations, for an explanation of schematic standards used in this manual.
The A1 Mother Board connects inter-board signals of the 371B. These include
control, drive, data, reference, and sense signals, as well as power supply and
ground lines.
The A2 CPU board contains the MPU circuits which consist of a 68000
Microprocessor, power-up reset circuit, clock generator, buffers, wait timing
generator, and an interrupt logic circuit.
Conventions
Mother Board
Microprocessor Unit
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...
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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...
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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 241: ...8 5 371B Service Manual Test Point Adjustment Locations 1...
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Page 249: ...Mechanical Parts List...
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Page 269: ...9 19 371B Service Manual Figure 9 4 Power Supply...
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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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