OHAUS T71P User manual

SERVICE MANUAL
7000 Series
T71 Indicators
T71P T71XW
Ohaus Corporation 19A Chapin Road, P.O. Box 2033, Pine Brook, NJ 07058-2033 [phone]

SERVICE MANUAL
7000 Series T71 Indicators:
T71P & T71XW
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 T71P and T71XW: Top and Bottom Housing ............................................................1-2
1.5 Specifications.............................................................................................................1-4
1.6 Hardware Setup or Disassembly...............................................................................1-5
1.6.1 Connecting the Scale Base’s Load Cell.............................................................1-5
1.6.2 Jumper Connections ..........................................................................................1-6
1.6.3 RS232 Interface .................................................................................................1-6
1.7 Operation...................................................................................................................1-7
1.7.1 Power Supply.....................................................................................................1-7
1.7.2 Overview of the Controls....................................................................................1-7
1.7.3 Overview of the Display Indicators.....................................................................1-7
1.7.4 Overview of the Control Functions .....................................................................1-8
1.7.5 Menu Setup........................................................................................................1-9
1.7.6 Language Menu Setup.....................................................................................1-12
1.8 Calibration................................................................................................................1-13
1.8.1 Zero Calibration................................................................................................1-13
1.8.2 Span Calibration...............................................................................................1-14
1.8.3 3-point Linearity Calibration..............................................................................1-15
1.8.4 5-point Linearity Calibration..............................................................................1-16
1.8.5 Calibration Test ................................................................................................1-17
1.8.6 Geographical Adjustment Factor......................................................................1-17
1.9 RS232 Interface Connection....................................................................................1-18
1.9.1 Setting Communications Parameters...............................................................1-18
1.9.2 Interface Commands........................................................................................1-19
1.9.3 Output Format..................................................................................................1-20
1.10 Legal For Trade (LFT) .............................................................................................1-21
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 Main Printed Circuit Board (PCB) Replacement.................................................3-2
3.2.1 Display Printed Circuit Board (PCB) Replacement.............................................3-3
3.2.3 Membrane Switch Replacement.........................................................................3-4
CHAPTER 4 TESTING
4.1. Testing.......................................................................................................................4-1
4.2 Power Test.................................................................................................................4-1
4.3 Performance Tests Using a Scale Base....................................................................4-1
Ohaus Corporation www.ohaus.com 1 7000 Series T71 Indicators Service Manual

TABLE OF CONTENTS
CHAPTER 4 TESTING (continued) Page No.
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.......................................................4-3
4.5 Calibration Retention Test.........................................................................................4-3
4.6 RS232 Interface Test.................................................................................................4.3
4.7 Print Test ...................................................................................................................4-3
CHAPTER 5 PARTS LISTS & DIAGRAMS
5-1 7000 Series T71P Indicator: Housing & Internal Parts..............................................5-2
5-2 7000 Series T71XW Indicator: Housing & Internal Parts...........................................5-4
APPENDIX A SETUP & CALIBRATION VALUES
Appendix A. Geographical Adjustment Values .................................................................. A-1
LIST OF TABLES
TABLE NO. TITLE Page No.
1-1 Specifications........................................................................................................1-3
1-2 Functions of Display Controls................................................................................1-7
1-3 Functions of Display Keypad.................................................................................1-8
1-4 T71 Menu Structure ..............................................................................................1-9
1-5 Interface Command Table...................................................................................1-18
1-6 Default Serial Output Format...............................................................................1-19
2-1 Diagnostic Guide...................................................................................................2-3
4-1 Increasing/Decreasing Load Test..........................................................................4-2
5-1 T71P Indicator: Housing & Internal Parts..............................................................5-3
5-2 T71XW Indicator: Housing & Internal Parts...........................................................5-5
A-1 Geographical Adjustment Values......................................................................... A-1
LIST OF ILLUSTRATIONS
FIGURE NO. TITLE
1-1 Top and Bottom Housing, and Rear Panel, T71P.................................................1-2
1-2 Top and Bottom Housing, and Rear Panel, T71XW..............................................1-3
1-3 Printed Circuit Board (PCB), T71 Indicator ...........................................................1-5
1-4 Load Cell Terminal Blocks J4 (Scale 1) and J7 (Scale 2).....................................1-5
1-5 Load Cell wiring.....................................................................................................1-6
1-6 Open/shorted jumpers...........................................................................................1-6
1-7 RS232 Pins ...........................................................................................................1-6
1-8 Battery charge symbol...........................................................................................1-7
1-9 T71 Display ...........................................................................................................1-7
1-10 T71 Display Indicator.............................................................................................1-7
1-11 Changing the menu language.............................................................................1-12
1-12 T71P Wire Seal...................................................................................................1-16
1-13 T71P Paper Seal.................................................................................................1-16
1-14 T71XW Wire Seal................................................................................................1-16
1-15 T71XW Paper Seal..............................................................................................1-16
2-1 Visual Checking Procedures.................................................................................2-1
5-1 Series 7000 T71P Indicator: Housing & Internal Parts..........................................5-2
5-1 Series 7000 T71XW Indicator: Housing & Internal Parts ......................................5-4
7000 Series T71 Indicators Service Manual 2 Ohaus Corporation www.ohaus.com

CHAPTER 1 GETTING STARTED
7000 Series T71 Indicator Service Manual 1-1 Ohaus Corporation www.ohaus.com
1.1 INTRODUCTION
This service manual contains the information needed to perform routine maintenance and
service on the Ohaus T71 Indicators. The contents of this manual are contained in five
chapters:
Chapter 1 Getting Started – Contains information regarding service facilities, tools and test
equipment, 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 T71 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, openwindows,
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.

CHAPTER 1 GETTING STARTED
Ohaus Corporation www.ohaus.com 1-2 7000 Series T71 Indicator Service Manual
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.
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.
1.4 Top and Bottom Housing
Figure 1-1. Top and Bottom Housing, and Rear Panel, T71P.
Adjusting
Knobs
Mounting
Bracket
Security screw
4 screws
Battery
Compartment
Power
Receptacle
RS232
Connector
Hole plug
for option
Scale 2 Load Cell Cable Gland
Scale 1 Load Cell
Cable Gland Load Cell Connector for Scale 1

CHAPTER 1 GETTING STARTED
7000 Series T71 Indicator Service Manual 1-3 Ohaus Corporation www.ohaus.com
1.4 Top and Bottom Housing
Figure 1-2. Top and Bottom Housing, and Rear Panel, T71XW.
Adjusting
Knobs
Mounting
Bracket
4 hex-head
bolts
RS232 Cable
Security screw Power Cord
RS232,
Scale 2 RS485/422
Scale 1 Load Cell
Cables
Relay Option Cable

CHAPTER 1 GETTING STARTED
Ohaus Corporation www.ohaus.com 1-4 7000 Series T71 Indicator Service Manual
1.5 SPECIFICATIONS
TABLE 1-1. SPECIFICATIONS
Model T71P T71XW
Maximum Displayed
Resolution 1:50,000
Maximum Approved Resolution 1:10,000
Maximum Counting Resolution 1:500,000
Weighing Units Kg, lb, g, oz, lb:oz, tonnes, custom
Functions Static Weighing, Dynamic Weighing, Parts Counting,
Checkweighing, Percent Weighing, Vehicle Weighing
Display 25 mm / 1 in High, 2-line LCD
Over/Accept/Under Indicators Red, Green, Yellow LED
Backlight White LED
Ingress Protection --- IP66
Load Cell Excitation Voltage 5V DC
Load Cell Drive Up to 8 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 1 kg or 1 lb to 100% capacity
Interfaces RS232, External Input; optional Com2*
Overall Dimensions
(W x D x H) (in/mm) 10.2 x 2.7 x 6.6 / 260 x 71 x 168 10.3 x 3.0 x 5.8 / 262 x 76 x 149
Net Weight (lb/kg) 3.3 / 1.5 7.7 / 3.5
Shipping Weight (lb/kg) 5 / 2.3 9.5 / 4.3
Operating Temperature Range –10°C to 40°C / /14°F to 104°F
Main Power 100-240 VAC / 50-60 Hz, Internal Universal Power Supply
Battery Power 6 C-type (LR14) Batteries Rechargeable battery pack
(option)
Rechargeable battery pack
(option)
*Can be either RS232 or RS422/485.