A & A Scales PT300 Manuals

Manuals and User Guides for A & A Scales PT300. We have 1 A & A Scales PT300 manual available for free PDF download: Service Manual

A & A Scales PT300 Service Manual

A & A Scales PT300 Service Manual (52 pages)

Brand: A & A Scales | Category: Scales | Size: 0.64 MB

Table of Contents

Rev B, October
2
Table of Contents
3
Scope of Manual

6
Specifications

7
- Electrical
  7
- Serial Interface Specifications
  7
- Physical
  7
- Environmental
  8
- Calibration
  8
- Figure 1 Block Diagram
  9
Theory of Operation

10
- Power Supply
  10
  - Input Protection
    10
  - Figure 2 Battery Charger
    10
  - Charger
    11
  - Switch
    11
  - Figure 3 Switch
    11
  - Low Voltage Sensor
    12
  - Regulator
    12
- Analog Section
  13
  - Instrumentation Amplifier
    13
  - Analog/Digital Converter
    13
  - Figure 4 Integrator/Comparitor
    13
  - Figure 5 Conversion Cycle
    14
  - Auto Zero
    14
  - Microprocessor Section
    15
    
    Cpu
    15
    
    Memory
    15
    
    Device Selector
    15
    
    Switches & Reader
    15
    
    Display Driver
    16
    
    Serial IN/OUT
    16
- Lcd Drive
  16
Troubleshooting

17
- Symptoms
  17
  - No Power Up, Nothing on Display
    17
  - Power up to Random Display
    17
  - Power up to Test Pattern
    17
  - Scale Shuts off
    18
  - Locks up
    18
  - No Backlight
    18
  - No Response to One or more Keys
    18
  - Bad" Weights
    18
  - Jumpy/Drifty Weights
    18
  - Slow Operation
    18
  - Low Batt Indicator Won't Turn off
    19
  - Batteries Won't Charge
    19
  - No Totalizing
    19
- Error Messages
  19
- Tests, Waveforms and
  20
- Voltage Measurements
  20
- System Checkout Procedure
  23
  - Charger Voltage
    23
  - On / off Switch
    23
  - Power Supplies
    23
  - Figure 9 Test Waveforms
    23
  - Amplifier
    24
  - A/D Converter
    24
  - Lamp
    24
  - Keys
    24
  - Low Batt Indicator
    24
  - Power down Shutoff
    24
  - SIO (Totalizing)
    25
  - Load Cells
    27
  - Figure 12 Load Cell Schematic
    27
Procedures

28
- Loading Pads & Blocks
  28
- Calibrate Span
  28
  - Calibration
    28
- Remove and Replace Main Circuit Board
  30
  - Disassembly
    30
  - Assembly
    30
- Remove and Replace Load Cell
  31
  - Disassembly
    31
  - Assembly
    32
- Check Front/Back Load Cell Balance
  32
- Figure 13 Load Cell Placement
  33
- Unpacking and Installation
  35
- Use of a Load Cell Simulator
  35
- Complete List of Required Tools and Materials
  35
  - Spare Parts List
    35
  - Connector Pinouts
    37
- Transmit Data Format
  37
- Pt300 Main Circuit Board
  38
- Parts List
  38
- Pt300 Summing Circuit Board Parts List
  40
- Figure 14 Summing Board
  41
Appendix A

41
- Schematics
  45
Appendix B

45
- Totalizing Cable
  48
- Charging Cable
  49
- Internal Cable Assembly
  51
Parts

52

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