OHAUS T51P User manual

SERVICE MANUAL
5000 Series
T51 Indicators
T51P T51XW
Ohaus Corporation 19A Chapin Road, P.O. Box 2033, Pine Brook, NJ 07058-2033 [phone]

SERVICE MANUAL
5000 Series T51 Indicators:
T51P & T51XW
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 Top and Bottom Housing...........................................................................................1-2
1.5 Specifications.............................................................................................................1-4
1.6 Hardware Setup or Disassembly...............................................................................1-5
1.6.1 Jumper Connections ..........................................................................................1-5
1.6.2 RS232 Interface .................................................................................................1-6
1.7 Operation...................................................................................................................1-7
1.7.1 Power Supply.....................................................................................................1-7
1.8 Overview of the Controls ...........................................................................................1-7
1.8.1 Overview of the Display Indicators.....................................................................1-7
1.8.2 Overview of the Control Functions .....................................................................1-8
1.8.3 Menu Setup........................................................................................................1-8
1.9 Calibration................................................................................................................1-10
1.9.1 Zero Calibration................................................................................................1-10
1.9.2 Span Calibration...............................................................................................1-11
1.9.3 Linearity Calibration..........................................................................................1-12
1.9.4 Calibration Test ................................................................................................1-13
1.9.5 Geographical Adjustment Factor......................................................................1-13
1.10 RS232 Interface Connection....................................................................................1-14
1.10.1 Setting Communications Parameters...............................................................1-14
1.10.2 Interface Commands........................................................................................1-15
1.10.3 Output Format..................................................................................................1-15
1.11 Legal For Trade (LFT) .............................................................................................1-16
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 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
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
Ohaus Corporation www.ohaus.com 1 5000 Series T51 Indicators Service Manual

TABLE OF CONTENTS
CHAPTER 4 TESTING (continued) Page No.
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 5000 Series T51P Indicator: Housing & Internal Parts..............................................5-2
5-2 5000 Series T51XW 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........................................................................................................1-4
1-2 T51P RS232 Pin Configuration.............................................................................1-6
1-3 T51XW RS232 Terminal .......................................................................................1-6
1-4 Functions of Display Controls................................................................................1-8
1-5 T51 Menu Structure ..............................................................................................1-9
1-6 Interface Command Table...................................................................................1-15
1-7 Default Serial Output Format...............................................................................1-15
2-1 Diagnostic Guide...................................................................................................2-3
4-1 Increasing/Decreasing Load Test..........................................................................4-2
5-1 T51P Indicator: Housing & Internal Parts..............................................................5-3
5-2 T51XW 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, T51P.................................................1-2
1-2 Top and Bottom Housing, and Rear Panel, T51XW..............................................1-3
1-3 Printed Circuit Board (PCB), T51 Indicator ...........................................................1-4
1-4 Load Cell wiring.....................................................................................................1-4
1-5 Open/shorted jumpers...........................................................................................1-4
1-6 RS232 Pins (T51P) ...............................................................................................1-5
1-7 RS232 Terminal (T51XW).....................................................................................1-5
1-8 Battery charge symbol...........................................................................................1-6
1-9 T51 Display ...........................................................................................................1-6
1-10 T51 Display Indicator.............................................................................................1-6
1-11 T51P Wire Seal...................................................................................................1-15
1-12 T51P Paper Seal.................................................................................................1-15
1-13 T51XW Wire Seal................................................................................................1-15
1-14 T51XW Paper Seal..............................................................................................1-15
2-1 Visual Checking Procedures.................................................................................2-1
5-1 Series 5000 T51P Indicator: Housing & Internal Parts..........................................5-2
5-1 Series 5000 T51XW Indicator: Housing & Internal Parts ......................................5-4
5000 Series T51 Indicators Service Manual 2 Ohaus Corporation www.ohaus.com

CHAPTER 1 GETTING STARTED
1.1 INTRODUCTION
This service manual contains the information needed to perform routine maintenance and
service on the Ohaus T51 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 T51 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.
5000 Series T51 Indicator Service Manual 1-1 Ohaus Corporation www.ohaus.com

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.
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
Adjusting
Knobs
Mounting
Bracket
Security screw
4 screws
Battery
Compartment
RS232
Connector
Power
Receptacle Hole plug
for option
Scale 2 Load Cell Cable Gland
Scale 1 Load Cell Cable Gland Load Cell Connector
for Scale 1
Figure 1-1. Top and Bottom Housing, and Rear Panel.
Ohaus Corporation www.ohaus.com 1-2 5000 Series T51 Indicator Service Manual

CHAPTER 1 GETTING STARTED
1.4 Top and Bottom Housing
Adjusting
Knobs
Mounting
Bracket
4 hex-head
bolts
RS485/422
Scale 1
RS232,
Scale 2
Relay Option Cable Load Cell
Cables
RS232 Cable
Power Cord
Security screw location
Figure 1-2. Top and Bottom Housing, and Rear Panel, T51XW.
5000 Series T51 Indicator Service Manual 1-3 Ohaus Corporation www.ohaus.com

CHAPTER 1 GETTING STARTED
1.5 SPECIFICATIONS
TABLE 1-1. SPECIFICATIONS
Model T51P T51XW
Capacity Range 5 to 20,000 kg or lb
Maximum Displayed
Resolution 1:30,000
Maximum Approved Resolution 1:10,000
Maximum Counting Resolution 1:300,000
Weighing Units Kg, lb, g, oz, lb:oz, tonnes, custom
Static Weighing, Dynamic Weighing, Counting,
Checkweighing, Percent Weighing
Functions
Display 25 mm / 1 in High 6-digit, 7-segment LCD
Over/Accept/Under Indicators Red, Green, Yellow LED
Backlight White LED
Keypad 4-button membrane switch
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 1 kg or 1 lb to 100% capacity
Interface RS232; optional Com2, either RS232 or RS422/485
Overall Dimensions
(W x D x H) (in/mm) 10.2 x 2.7 x 6.5 / 260 x 71 x 166 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
AC Power 100-240 VAC / 50-60 Hz, Internal Universal Power Supply
Battery Power 6 C-type (LR14) disposable Batteries (T51P),
optional 7.2v rechargeable NiMH Battery Pack
Ohaus Corporation www.ohaus.com 1-4 5000 Series T51 Indicator Service Manual

CHAPTER 1 GETTING STARTED
1.6 HARDWARE SETUP OR DISASSEMBLY
Both the T51P and T51XW connect to a base scale through a Load Cell Cable that connects to
the Indicator’s Main Printed Circuit Board (PCB). Each model has a mounting bracket that can
be attached to a column mount bracket or a wall mount. 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:
T51P:
1. Remove the four Phillips head screws
from the rear housing.
2. Open the housing; disconnect the
ribbon cable from the top of the PCB.
T51XW:
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 T51’s Main PCB, with connectors, jumpers, terminals and switches
indicated.
Figure 1-3. Printed Circuit Board (PCB), T51 Indicator.
Power Supply
connector
Battery
connector J2
(T51P only)
Alternate
Load Cell
Terminal J4
Sense
Jumper W1
Sense
Jumper W2
Security Switch
SW2
RS232
Terminal J7
(T51XW only)
External Input
Terminal Block
COM2
Connector J8
(Optional:
RS232 or
RS422/485
)
Load Cell
Connector Plug
Recharge
option-T51P
(opposite side)
1.6.1 Jumper Connections RS232 Pin Connector
(T51P only)
For a 4-wire load cell with no sense wires, short Jumpers W1 and W2.
For a 6-wire load cell that includes sense wires, open Jumpers W1 and W2.
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 1-4. Load Cell wiring.
Pin Connection
J4-1 +Excitation
J4-2 +Sense
J4-3 +Signal
J4-4 GND
J4-5 –Signal
J4-6 –Sense
J4-7 –Excitation
Figure 1-5. Open/shorted jumpers.
5000 Series T51 Indicator Service Manual 1-5 Ohaus Corporation www.ohaus.com

CHAPTER 1 GETTING STARTED
1.6.2 RS232 Interface
The T51P and T51XW have a built-in RS232 Interface. The T51P has a standard 9-pin D-style
female connector on the back of the T51P Housing. (See Table 1-2 for Pin Configuration.)
The T51XW has terminals for connecting a cable directly to the main PCB. (See Figure 1-1,
Terminal J7, and Table 1-3 for Pin Configuration). In addition, each model (T51P and T51XW),
has an optional COM2 connector, which can be either RS232 or RS422/485. The optional
interface is available separately, with its own instructional manual for installation and
configuration.
TABLE 1-2. T51P RS232 PIN CONFIGURATION.
1
2
3
4
5
6
78
9
Figure 1-6. RS232 Pins.
(T51P)
Pin Connection
1 N/C
2 TXC
3 RXD
4 N/C
5 GND
6 N/C
7 CTS
8 RTS
9 N/C
TABLE 1-3. T51XW RS232 TERMINAL CONFIGURATION.
Figure 1-7. RS232 Terminal.
(T51XW)
Pin Connection
1 RTS
2 TXD
3 RXD
4 CTS
5 GND
For software setup of the RS232 Interface through the Indicator’s menu, see Section 1.9.
All other aspects of hardware configuration and setup are described in the Instruction Manual.
Ohaus Corporation www.ohaus.com 1-6 5000 Series T51 Indicator Service Manual

CHAPTER 1 GETTING STARTED
1.7 OPERATION
This section contains information on the basic operation of the Indicator. An exploded view
drawing is included in Chapter 5 which identifies all components of the indicator. The
descriptions in this manual refer to the names of the components identified in the exploded view
drawing with the numbered callout.
1.7.1 Power Supply
Both models have an Internal Universal Power Supply, 100-240 VAC / 50-60 Hz, and plug into a
standard, properly grounded electrical outlet.
The T51P indicator can also be operated on six alkaline
batteries (not supplied) when AC power is not available.
(An optional rechargeable battery system is also available.)
The Indicator will automatically switch to battery operation if
there is power failure or the power cord is removed. The
indicator can operate for up to 80 hours on battery power.
During battery operation, the battery charge symbol indicates
the battery status. The indicator will automatically turn-off
when the batteries are fully discharged.
0 % - 5 % charged
5 % - 25 % charged
26 % - 50 % charged
51 % - 75 % charged
76 % - 100 % charged
Figure 1-8. Battery charge
symbol.
1.8 OVERVIEW OF THE CONTROLS
Capacity label
windo
w
Under, Accept
& Over LEDs
Stability &
Zero symbols Kilogram,
Pound, &
Ounce symbols
(For complete list,
see Figure 1-7.)
7-segment, 6-digit
LED display
Brutto, Gross
symbols
(For complete list,
see Figure 1-8.) Control Buttons
Figure 1-9. T51 Display.
1.8.1 OVERVIEW OF THE DISPLAY INDICATORS
Scale symbol
(
not used
)
Center of Zero
indicator
Ne
g
ative s
y
mbol
Net symbol Range symbol
Kilogram, Gram,
Percent, Pound,
Ounce, Pound: Ounce,
Tonne, Pieces
s
y
mbols
Stable weight
indicato
r
Preset Tare,
Tare, Brutto,
Gross symbols Figure 1-10. T51 Display Indicator. Dynamic
symbol
Battery charge
symbol
5000 Series T51 Indicator Service Manual 1-7 Ohaus Corporation www.ohaus.com

CHAPTER 1 GETTING STARTED
1.8.2 OVERVIEW OF THE CONTROL FUNCTIONS
TABLE 1-4. FUNCTIONS OF DISPLAY CONTROLS
Button
Primary
Function
(Short Press)
ON/ZERO
Turns the
Indicator on
If Indicator is on,
sets zero.
PRINT
Sends the current
value to the COM
port if AUTOPRINT
is set to Off.
FUNCTION
Initiates an
application
mode.
Temporarily
displays the
active mode’s
reference data.
TARE
Performs a tare
operation.
Secondary
Function
(Long Press)
Off
Turns the
Indicator off.
Units
Changes the
weighing unit.
Mode
Allows changing
the application
mode.
Press and hold
allows scrolling
through modes.
Menu
Enter the User
menu.
Menu
Function
(Short Press)
Yes
Accepts the
current setting
on the display.
No
Advances to the
next menu or
menu item.
Rejects the current
setting on the
display and
advances to the
next available
setting.
Increments the
value.
Back
Moves back
to previous menu
item.
Decrements the
value.
Exit
Exits the User
menu.
Aborts a
calibration in
progress.
1.8.3 Menu Setup
To enter the Menu Mode, press and hold the TARE/Menu button until MENU appears on the
display. The first upper level menu appears on the display.
Use Yes, No, Back,and Exit to navigate in Menu Mode:
– Yes Allows entry into the displayed menu.
Accepts the displayed setting and advances to the next menu item.
– No Skips by the displayed menu.
Rejects the displayed setting or menu item and advances to the next available item.
– Back Moves backwards through the upper and middle level menus.
Backs out of a list of selectable items to the previous middle level menu.
– Exit Exits from menu directly to the active weighing mode.
Ohaus Corporation www.ohaus.com 1-8 5000 Series T51 Indicator Service Manual

CHAPTER 1 GETTING STARTED
1.8.3 Menu Setup
Table 1-5. T51 MENU STRUCTURE
→CALIBRATION →SETUP →READOUT →
MODE → UNIT → GMP → PRINT 1 →
ZERO1
SPAN1
LINEARITY1
CAL TEST
GEO1
END CAL
RESET
RANGE2
CAPACITY2
GRADUATION2
POWER ON2
ZERO RANGE2
AUTO TARE2
RETAIN WEIGHT2
LEGAL FOR TRADE
BEEPER VOLUME
BEEPER SIGNAL
BUTTON BEEPER
END SETUP
RESET
STABLE RANGE2
FILTER
AUTO ZERO2
BACKLIGHT
AUTO OFF TIMER
GROSS INDICATOR
END READOUT
RESET
WEIGH2
COUNT2
PERCENT2
DYNAMIC2
CHECK WEIGH2
END MODE
RESET
KILOGRAM2
POUND2
GRAM2
OUNCE2
POUND:OUNCE2
TONNE2
CUSTOM2
END UNIT
RESET
DATE
-DATE TYPE
-DATE SET
TIME
-TIME TYPE
-TIME SET
USER ID
PROJECT ID
SCALE ID
END GMP
RESET
STABLE ONLY2
AUTO PRINT
CONTENT
-RESULT
-GROSS
-NET
-TARE
-HEADER
-USER ID
-PROJECT ID
-SCALE ID
-DIFFERENCE
-DATE TIME
-INFO
-MODE
-NAME
LAYOUT
-FORMAT
-FEED
LIST
END PRINT1
→PRINT 2 →COM 1 →COM 2 →
I-O → LOCK MENU → LOCK KEY → END →
RESET
STABLE ONLY2
AUTO PRINT
CONTENT
-RESULT
-GROSS
-NET
-TARE
-HEADER
-USER ID
-PROJECT ID
-SCALE ID
-DIFFERENCE
-DATE TIME
-INFO
-MODE
-NAME
LAYOUT
-FORMAT
-FEED
LIST
END PRINT2
RESET
BAUD
PARITY
STOP BIT
HANDSHAKE
ALT. COMMAND
-PRINT
-TARE
-ZERO
END COM1
RESET
BAUD
PARITY
STOP
ADDRESS3
HANDSHAKE
ALT. COMMAND
-PRINT
-TARE
-ZERO
END COM2
RESET
EXT. INPUT
INPUT BEEP
RELAY OUTPUT
-TYPE
-SEQUENCE
-CONTACT
-STABLE
END I-O
RESET
LOCK CAL
LOCK SETUP
LOCK READDOUT
LOCK MODE
LOCK UNIT
LOCK PRINT1
LOCK PRINT2
LOCK COM1
LOCK COM2
LOCK GMP
LOCK I/O
END LOCK MENU
RESET
LOCK ALL
LOCK OFF
LOCK ZERO
LOCK PRINT
LOCK UNIT
LOCK FUNCTION
LOCK MODE
LOCK TARE
LOCK MENU
END LOCK KEY
Notes:
1. Hidden when LEGAL FOR TRADE is ON.
2. Locked at current setting when LEGAL FOR TRADE is ON.
3. Visible only with RS422/485 option installed.
5000 Series T51 Indicator Service Manual 1-9 Ohaus Corporation www.ohaus.com

CHAPTER 1 GETTING STARTED
1.9 CALIBRATION
Three calibration processes are available: Zero, Span, and Linearity Calibration. In addition, a
Calibration Test and Geographical Adjustment Factor setting are accessible from the CAL
menu.
Preliminary Steps:
1. Be sure appropriate calibration masses are available before beginning calibration.
2. Be sure the scale base is level and stable during the entire calibration process.
3. If LFT is set to On, calibration is unavailable.
To set LFT to OFF, see Section 1.10, page 1-13.
Note: To use the LFT mode again after turning it off, it is necessary to have the
Indicator locked and sealed by local Weights and Measures authorities.
4. If the Calibration Menu is locked in the Menu Lock submenu, turn it back on:
– Press and hold TARE/Menu until C.A.L. appears, then press No continuously until:
– L.MENU appears. Press Yes. RESET appears. Press No.
– L.CAL appears. Press Yes. OFF flashes. Press Yes.
– Press No continuously until End.LM appears. Press Yes.
– L.Key appears. Press No. END appears. Press Yes to exit menu mode.
5. Allow the Indicator to warm up for approximately ten minutes after stabilizing to room
temperature.
6. To abort calibration, press the Exit button anytime during the calibration process.
1.8.1 Zero Calibration
Zero calibration uses one calibration point. The zero calibration point is established with no
weight on the scale. Use this calibration method to adjust for a different pre-load without
affecting the span or linearity calibration.
Press and hold TARE/Menu until C.A.L. appears, then press Yes.
(LFt.NO appears briefly before C.A.L., if the Indicators is not in LFT mode.)
ZErO appears. Press Yes to initiate Zero Calibration.
The display flashes 0 and the calibration unit. Press Yes to establish the
zero point.
The display shows --C-- while the zero point is established.
When zero calibration is completed, the display shows dONE.
Then the scale exits to the active weighing mode and displays the actual
weight value.

Ohaus Corporation www.ohaus.com 1-10 5000 Series T51 Indicator Service Manual

CHAPTER 1 GETTING STARTED
1.9.2 Span Calibration
Span Calibration uses two points to adjust the Indicator. The first point is the zero value, where
there is no weight on the scale. The second point is the Span value, where a calibration mass
is placed on the scale.
Press and hold TARE/Menu until MENU appears. Press Yes.
(LFt.NO appears, then C.A.L., if the Indicator is not in LFT mode.)
Press Yes. SPAN appears. Press Yes to initiate Span Calibration.
The display flashes the span calibration point. Place the specified weight
on the scale and press Yes.
To choose a different span point, press No to increment the selections, or Back to decrement
the selections. When the desired value is displayed, place the specified weight on the scale
and press Yes.
The display shows --C-- while the span point is established.
The display flashes 0. With no weight on the scale, press Yes to establish
the zero point.
The display shows --C-- while the zero point is established.
When span calibration is completed, the display shows dONE.
The scale exits to the active weighing mode and displays the actual weight
value.

5000 Series T51 Indicator Service Manual 1-11 Ohaus Corporation www.ohaus.com

CHAPTER 1 GETTING STARTED
1.9.3 Linearity Calibration
Linearity calibration uses three calibration points. The full calibration point is established with a
weight on the scale. The mid-calibration point is established with a weight equal to half of the full
calibration weight on the scale. The zero calibration point is established with no weight on the
scale. The mid-calibration points cannot be altered by the user during the calibration procedure.
Press and hold TARE/Menu until C.A.L. appears, then press Yes.
(LFt.NO appears briefly before C.A.L., if the Indicators is not in LFT mode.)
ZERO appears. . Press No. SPAN appears. Press No. Linearity appears.
Press Yes to initiate Linearity Calibration.
The display flashes the full calibration point and calibration unit.
Place the specified weight on the scale and press Yes.
To choose a different full point or calibration unit (kg or lb), press No to increment the
selections, or Back to decrement the selections. When the desired value is displayed,
place the specified weight on the scale and press Yes.
The display shows --C-- while the full calibration point is established.
The display flashes the mid-calibration point. Place the specified weight on
the scale and press Yes.
The display shows --C-- while the mid-calibration point is established.
The display flashes 0. With no weight on the scale, press Yes to establish the
zero point.
The display shows --C-- while the zero point is established.
When linearity calibration is completed, the display shows dONE.
The scale exits to the active weighing mode and displays the actual weight
value.

Ohaus Corporation www.ohaus.com 1-12 5000 Series T51 Indicator Service Manual

CHAPTER 1 GETTING STARTED
1.9.4 Calibration Test
Calibration test is used to compare a known calibration weight against the stored span
calibration data.
NOTE: Calibration Test is always available (even when LFT is set to ON).
Press and hold TARE/Menu until C.A.L. appears, then press Yes.
(LFt.NO appears briefly before C.A.L., if the Indicators is not in LFT mode.)
ZERO appears. . Press No. SPAN appears. Press No. Linearity appears.
Press No. tESt appears. Press Yes to initiate Calibration Test.
The display flashes 0. With no weight on the scale, press Yes to record the
current zero point.
The display shows --t-- while the zero point is recorded.
The display flashes the span calibration weight using the value from the last
calibration. The example shows test weight of 30 kg.
Place the specified test weight on the scale and press Yes.
The display shows --t-- while the data is processed.
The display flashes the actual difference between the calibration data and the
test weight.
The example shows a 0.010 kg difference. If printing is enabled, the result of
the Calibration Test is printed.
After 5 seconds, Calibration Test ends, the scale returns to the active weighing
mode and displays the current weight.

1.9.5 Geographical Adjustment Factor
The Geographical Adjustment Factor (GEO) is used to compensate for variations in gravity.
To determine the GEO factor that corresponds to your location, see Appendix A.
Note: Changing the GEO Factor alters the calibration. The GEO value was set at the factory
and should only be changed if the location of use varies from the default setting.
To adjust the GEO Factor, press and hold TARE/Menu until C.A.L. appears. Press Yes.
ZERO appears. Press No. SPAN appears. Press No. Linearity appears. Press No.
GEO appears. Press Yes. The default GEO setting appears. Press No to increment the
number, or Back to decrement, until the desired number appears. Then press Yes.
GEO appears again. Press No to exit the GEO menu. End appears. Press Yes to return to
the CAL menu. Press No continuously until E.n.d appears. Press Yes to return to weighing
mode.
5000 Series T51 Indicator Service Manual 1-13 Ohaus Corporation www.ohaus.com

CHAPTER 1 GETTING STARTED
1.10 RS232 INTERFACE CONNECTION
The T51 has a bi-directional RS232 interface for communication with printers and computers.
When the Indicator is connected to a printer or Programmable Logic Controller (PLC), displayed
data can be output various ways, depending on PRINT menu settings.
For hardware setup of the RS232 Interface, see Section 1.5.2, page 1-5.
1.10.1 Setting Communications Parameters (COM1)
Note: Only the COM1 menu appears unless the second communication interface is set up.
The T51 Indicator’s default communication parameters are baud rate 9600 bits per second
(bps), 8 databits, no parity,Handshake XON/XOFF, Address Off, Alt Command (for Print) Off,
Alt Tare Off, and Alt Zero Off.
To change these settings use the COM1 menu, as follows:
1. Press and hold TARE/Menu until C.A.L. appears. Press No continuously until:
COM1 appears. Press Yes.
RESEt appears. Press No (unless you want to restore the factory defaults).
2. bAUd appears. Press Yes.
3. The default Baud rate setting, 9600 bps, appears. To change the setting, press No.
The menu cycles to the next setting each time you press No: first 9600, then 300, 600,
1200, 2400, 4800, and 9600 again. Press Yes when the desired setting appears.
bAUd appears again. Press No.
4. PAritY appears. Press Yes. The default Parity setting,
8 NONE, appears. To change the setting, press No.
The menu cycles to the next setting each time you press No:
first 7 Even, then 7 Odd, 7 None, and 8 None again. Press Yes
to accept a setting. PAritY appears again. Press No.
5. StOP appears. Press Yes. The default Stop Bit setting, 1,
appears. To change the setting, press No.
The menu toggles to the next setting each time you press No:
first 1, then 2, then 1 again. Press Yes when the desired setting
appears. StOP appears again. Press No.
6. HANdsh appears. Press Yes. The default Handshake setting,
On-Off (Xon/Xoff), appears. To change the setting, press No.
The menu toggles to the next setting each time you press No:
first Off, then On-Off, then Off again. Press Yes when the
desired setting appears. HANd appears again. Press No.
7. Alt.CM appears. Press Yes to set a different command
character for the P (Print), T (Tare) and Z (Zero) commands.
Otherwise, press No. Then press Yes when End.C1 appears.
At this point, if a second communication interface is present, the COM2 menu is available.
Otherwise, press Exit to return to weighing mode.
Ohaus Corporation www.ohaus.com 1-14 5000 Series T51 Indicator Service Manual