OHAUS 3000 Series T31P User manual

SERVICE MANUAL
3000 Series
T31 Indicators
T31P T31XW
Ohaus Corporation 19A Chapin Road, P.O. Box 2033, Pine Brook, NJ 07058-2033 [phone]

SERVICE MANUAL
3000 Series T31 Indicators:
T31P & T31XW
The information contained in this manual is believed to be accurate at the time of publication, but Ohaus
Corporation assumes no liability arising from the use or misuse of this material. Reproduction of this
material is strictly prohibited.
Material in this manual is subject to change.
© Copyright 2008 Ohaus Corporation, all rights reserved.
TM Registered trademark of Ohaus Corporation.

TABLE OF CONTENTS
CHAPTER 1 GETTING STARTED Page No.
1.1 Introduction................................................................................................................1-1
1.2 Service Facilities........................................................................................................1-1
1.3 Tools and Test Equipment Required.........................................................................1-2
1.3.1 Special Tools and Test Equipment List..............................................................1-2
1.3.2 Standard Tools and Test Equipment List ...........................................................1-2
1.4 Specifications.............................................................................................................1-3
1.5 Hardware Setup or Disassembly...............................................................................1-4
1.5.1 Jumper Connections ..........................................................................................1-4
1.5.2 RS232 Interface .................................................................................................1-5
1.6 Operation...................................................................................................................1-6
1.6.1 Power Supply .....................................................................................................1-6
1.7 Overview of the Controls ...........................................................................................1-6
1.7.1 Power On ...........................................................................................................1-7
1.7.2 Power Off ...........................................................................................................1-7
1.7.3 Menu Setup........................................................................................................1-8
1.8 Scale Setup & Calibration..........................................................................................1-9
1.8.1 Geographical Adjustment Factor........................................................................1-9
1.8.2 Span Calibration...............................................................................................1-10
1.8.3 Linearity Calibration..........................................................................................1-10
1.9 RS232 Interface Connection....................................................................................1-11
1.9.1 Setting Communications Parameters...............................................................1-11
1.9.2 Interface Commands........................................................................................1-12
1.9.3 Output Format ..................................................................................................1-12
1.10 Legal For Trade (LFT) .............................................................................................1-13
CHAPTER 2 TROUBLESHOOTING
2.1 Introduction................................................................................................................2-1
2.2 Visual Inspection........................................................................................................2-1
2.3 Diagnostic Guide .......................................................................................................2-2
2.2.1 Diagnosis............................................................................................................2-2
CHAPTER 3 MAINTENANCE PROCEDURES
3.1 Preventive Maintenance............................................................................................3-1
3.1.1 Preventive Maintenance Checklist .....................................................................3-1
3.2 Replacement of Major Components..........................................................................3-1
3.2.1 Printed Circuit Board (PCB) Replacement .........................................................3-2
3.2.2 Cable Set Replacement .....................................................................................3-3
3.2.3 Function Label & Membrane Switch Replacement.............................................3-3
3.2.4 Power Supply Replacement...............................................................................3-4
3.2.5 Battery Replacement..........................................................................................3-5
CHAPTER 4 TESTING
4.1. Testing.......................................................................................................................4-1
4.2 Power Test.................................................................................................................4-1
4.3 Performance Tests Using a Scale Base....................................................................4-1
4.3.1 Increasing/Decreasing Load Test.......................................................................4-2
4.3.2 Overload/Underload Test ...................................................................................4-2
4.4 Performance Tests Using a Load Cell Simulator.......................................................4-2
4.5 Calibration Retention.................................................................................................4-2
4.6 RS232 Interface Test/Print Test ................................................................................4.2
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TABLE OF CONTENTS
CHAPTER 5 PARTS LISTS & DIAGRAMS Page No.
5-1 3000 Series T31P Indicator: Housing & Internal Parts..............................................5-2
5-2 3000 Series T31XW Indicator: Housing & Internal Parts...........................................5-4
APPENDIX A SETUP & CALIBRATION VALUES
Appendix A. Setup & Calibration Values............................................................................ A-1
APPENDIX B GEOGRAPHICAL ADJUSTMENT VALUES
Appendix B. Geographical Adjustment Values .................................................................. B-1
LIST OF TABLES
TABLE NO. TITLE Page No.
1-1 Specifications........................................................................................................1-3
1-2 Functions of Display Controls................................................................................1-7
1-3 T31 Menu Structure ..............................................................................................1-8
1-4 Interface Command Table...................................................................................1-12
2-1 Diagnostic Guide...................................................................................................2-3
4-1 Increasing/Decreasing Load Test..........................................................................4-2
5-1 T31P Indicator: Housing & Internal Parts..............................................................5-3
5-2 T31XW Indicator: Housing & Internal Parts...........................................................5-5
A-1 Setup & Calibration Values .................................................................................. A-1
B-1 Geographical Adjustment Values......................................................................... B-1
LIST OF ILLUSTRATIONS
FIGURE NO. TITLE
1-1 Printed Circuit Board (PCB), T31 Indicator ...........................................................1-4
1-2 Load Cell wiring.....................................................................................................1-4
1-3 Open/shorted jumpers...........................................................................................1-4
1-4 Rear panel, T31XW...............................................................................................1-5
1-5 RS232 Pins ...........................................................................................................1-5
1-6 T31 Display ...........................................................................................................1-6
1-7 T31P Wire Seal...................................................................................................1-13
1-8 T31P Paper Seal.................................................................................................1-13
1-9 T31XW Wire Seal................................................................................................1-13
1-10 T31XW Paper Seal..............................................................................................1-13
2-1 Visual Checking Procedures.................................................................................2-1
5-1 Series 3000 T31P Indicator: Housing & Internal Parts..........................................5-2
5-1 Series 3000 T31XW Indicator: Housing & Internal Parts ......................................5-4
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CHAPTER 1 GETTING STARTED
1.1 INTRODUCTION
This service manual contains the information needed to perform routine maintenance and
service on the Ohaus T31 Indicators. The contents of this manual are contained in five
chapters:
Chapter 1 Getting Started – Contains information regarding service facilities, tools and test
equipment, measuring masses, specifications, hardware setup or disassembly, operating the
Indicator, scale setup and calibration, and configuring the Indicator’s communication and Legal-
for-Trade menus.
Chapter 2 Troubleshooting – Contains a diagnosis/diagnostics chart and error code table.
Chapter 3 Maintenance Procedures – Contains preventive maintenance procedures and
disassembly, repair and replacement procedures.
Chapter 4 Testing – Contains an operational test, segment display test, performance tests and
adjustments.
Chapter 5 Drawings and Parts Lists – Contains exploded views of T31 Indicators, identifying
all serviceable components.
Before servicing the indicator, you should be familiar with the Instruction Manual which is
packed with every indicator.
1.2 SERVICE FACILITIES
To service an indicator, the service area should meet the following requirements:
•Must be protected from electrostatic discharge.
•Should be temperature controlled and meet the indicator specifications for temperature
environmental requirements. See specifications for temperature range.
•Must be free of vibrations such as fork lift trucks close by, large motors, etc.
•Must be free of air currents or drafts from air conditioning/heating ducts, open windows,
people walking by, fans, etc.
•Area must be clean and air must not contain excessive dust particles.
•Work surface must be stable and level.
•Work surface must not be exposed to direct sunlight or radiating heat sources.
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CHAPTER 1 GETTING STARTED
1.3 TOOLS AND TEST EQUIPMENT REQUIRED
In order to properly service the Indicator, certain special tools and test items are required in
addition to standard electronic tool kits. These items are listed as follows:
1.3.1 Special Tools and Test Equipment List
1. Ohaus Scale Base.
2. Load Cell Simulator optional.
3. Computer with RS232 Interface for testing the RS232 communications.
4. RS232 Interface cable.
5. Data Printer for use with RS232 communications.
6. ESD work station or mat.
1.3.2 Standard Tools and Test Equipment List
1. Standard Electronics Tool Kit
2. Digital Voltmeter (DVM), with clip on probes. Input impedance of at least 10 megohms in
the 1 Volt dc position.
3. Soldering Iron, solder and flux remover.
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CHAPTER 1 GETTING STARTED
1.4 SPECIFICATIONS
TABLE 1-1. SPECIFICATIONS
Model T31P T31XW
Capacity Range 5 to 20,000 kg or lb
Maximum Displayed
Resolution 1:20,000
Approved Resolution 1:6,000
Maximum Avg. Piece Weight 1d
Weighing Units Kg, lb, g, oz, lb:oz
Functions Weighing, Parts Counting
Display 1 in/2.5 cm digit height, 6-digit, 7-segment
1.5 in/3.8 cm high x 4.9 in/12.5 cm wide backlit LCD
Backlight White LED
Keypad 4-button mechanical switches 4-button membrane switches
Ingress Protection --- IP66
Load Cell Excitation Voltage 5V DC
Load Cell Drive Up to 4 x 350 ohm load cells
Load Cell Input Sensitivity Up to 3mV/V
Stabilization Time Within 2 seconds
Auto-Zero Tracking Off, 0.5, 1 or 3 divisions
Zeroing Range 2% or 100% of capacity
Span Calibration 5 kg or 5 lb to 100% capacity
Interface RS232
Overall Dimensions
(W x D x H) (in/mm) 8.2 x 2.8 x 6.5 / 210 x 71 x 168 8.3 x 2.8 x 5.8 / 212 x 71 x 149
Net Weight (lb/kg) 3.6 / 1.6 6.6 / 2.9
Shipping Weight (lb/kg) 5.7 / 2.6 8.8 / 4.0
Operating Temperature Range –10°C to 40°C / /14°F to 104°F
Power 9 – 12 VDC, 0.5A, AC Adapter Internal rechargeable,
Sealed Lead-Acid Battery (100-hour typical life) (T31P)
100-240 VAC / 50-60 Hz, Internal Power Supply (T31XW)
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CHAPTER 1 GETTING STARTED
1.5 HARDWARE SETUP OR DISASSEMBLY
Both the T31P and T31XW connect to a scale base through a Load Cell Cable that connects to
the Indicator’s Main Printed Circuit Board (PCB). When supplied as part of a scale, each model
has a mounting bracket that attaches to the column bracket of the base scale. To remove the
mounting bracket, remove the threaded knobs, holding the Indicator by hand.
CAUTION:
ELECTRICAL SHOCK HAZARD. REMOVE ALL POWER CONNECTIONS TO THE
INDICATOR BEFORE SERVICING OR MAKING INTERNAL CONNECTIONS.
The process of opening the Housing varies slightly for each model:
T31P:
1. Remove the four Phillips head screws
from the rear housing.
2. Open the housing, being careful not to
disturb the internal connections.
T31XW:
1. Remove the four hex head screws from
the rear housing.
2. Open the housing by carefully pulling
the top of the front housing forward.
Below is a diagram of the T31’s Main PCB, with connectors, jumpers, terminals and switches
indicated. The Load Cell Cable connects to Terminal Block J5.
OFF ON
J7 J6
J5
W1 W2
J4
Membrane Switch
connector
(T31XW only)
RS232
Terminal J7
(T31XW only)
Sense
Jumper W2
LFT On/Off
Switch
Sense
Jumper W1
Load Cell
Terminal J5
RS232
Terminal J6
(T31P only)
Figure 1-1. Printed Circuit Board (PCB), T31 Indicator
Battery
connector
(T31P only)
1.5.1 Jumper Connections
For a 4-wire load cell with no sense wires, short Jumpers W2 and W3.
For a 6-wire load cell that includes sense wires, open Jumpers W2 and W3.
For load cells with an extra ground shield wire, connect the shield to the center position (GND).
+EXC +SIG -SIG -EXC
+SENS GND -SENS
Figure 1-2. Load Cell wiring.
Pin Connection
J5-1 +Excitation
J5-2 +Sense
J5-3 +Signal
J5-4 GND
J5-5 –Signal
J5-6 –Sense
J5-7 –Excitation
Figure 1-3. Open/shorted jumpers.
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