OHAUS EB SERIES User manual

EB SERIES SCALES
SERVICE MANUAL
Ohaus Corporation 7 Campus Drive, Suite 310, Parsippany, NJ 07054 [phone]

EB SERIES SCALES
SERVICE MANUAL
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 2011 Ohaus Corporation, all rights reserved.
® Registered trademark of Ohaus Corporation.

TABLE OF CONTENTS
EB Series Scales Service Manual i Ohaus Corporation www.ohaus.com
CHAPTER 1 GETTING STARTED Page No.
1 Introduction..............................................................................................................1-1
1.1 Service Facilities......................................................................................................1-1
1.2 Tools and Test Equipment Required........................................................................1-2
1.2.1 Standard Tools and Test Equipment.................................................................1-2
1.2.2 Special Tools....................................................................................................1-2
1.3 Calibration Masses Required...................................................................................1-2
1.4 Service Strategy.......................................................................................................1-2
1.5 Specifications...........................................................................................................1-3
1.6 Scale Settings..........................................................................................................1-4
CHAPTER 2 DIAGNOSIS
2. Diagnosis.................................................................................................................2-1
2.1 Scale Setup and Examination..................................................................................2-1
2.2 Preliminary Checks..................................................................................................2-1
2.3 Troubleshooting Tables............................................................................................2-1
2.4 EB Series Scales Error Code Table.........................................................................2-5
2.5 Testing the AC Adapter............................................................................................2-6
2.6 Testing the Membrane Switch..................................................................................2-6
2.7 Testing the Load Cell Assembly...............................................................................2-7
2.7.1 Resistance Test................................................................................................2-7
2.7.2 Excitation and Output Voltage Test...................................................................2-7
2.8 Testing the Main PC Board......................................................................................2-9
2.8.1 Main PC Board Voltage Measurements............................................................2-9
2.8.2 Simulator Testing..............................................................................................2-9
2.8.2.1General Load Test..................................................................................2-10
2.8.2.2Calibration Test......................................................................................2-10
2.9 Testing the Battery.................................................................................................2-11
2.9.1 Precautions for Battery Handling.....................................................................2-11
2.9.2 Battery Tests...................................................................................................2-11
CHAPTER 3 REPAIR PROCEDURES
3. Repair Procedures...................................................................................................3-1
3.1 Removing Top Housing............................................................................................3-1
3.2 Replacing The Membrane Switch.............................................................................3-2
3.3 Main Printed Circuit Board .......................................................................................3-4
3.3.1 Main Printed Circuit Board Replacement ..........................................................3-4
3.3.2 Display Printed Circuit Board Replacement.......................................................3-7
3.3.3 LCD Replacement.............................................................................................3-8
3.4 Replacing the Load Cell Assembly (with Frame)......................................................3-9
3.5 Replacing the Load Cell Component......................................................................3-11
3.5.1 Overload Protection Stop Adjustment .............................................................3-12
3.6 Replacing the Battery.............................................................................................3-14
CHAPTER 4 FINAL TESTING & CALIBRATION
4.1. Performance Tests...................................................................................................4-1
4.1.1 Segment Display Test.......................................................................................4-1
4.1.2 Repeatability Test.............................................................................................4-1
4.1.3 Off-Center Load Test........................................................................................4-3
4.1.4 Linearity Test....................................................................................................4-4
4.2 Calibration................................................................................................................4-6
4.2.2 Span Calibration ...............................................................................................4-6

TABLE OF CONTENTS
Ohaus Corporation www.ohaus.com ii EB Series Scales Service Manual
CHAPTER 5 DRAWINGS AND PARTS LISTS Page No.
5. Drawings and Parts Lists..........................................................................................5-1
Appendix A SERVICE MODES
A.1 Entering the Service Menu.....................................................................................A-1
A.2 Service Calibration..................................................................................................A-1
A.3 Scale Configuration.................................................................................................A-2
LIST OF TABLES
TABLE NO. TITLE Page No.
1-1 Calibration Masses..............................................................................................1-2
1-2 Specifications ......................................................................................................1-3
1-3 Menu Structure....................................................................................................1-4
2-1 Scale Will Not Turn On With AC Adapter.............................................................2-1
2-2 Scale Will Not Turn On Using Battery Power.......................................................2-2
2-3 Scale Does Not Respond To Front Panel Controls..............................................2-3
2-4 No Display or Partial Display ...............................................................................2-3
2-5 Balance Reading Incorrect or Unstable................................................................2-4
2-6 Cannot Calibrate the Scale..................................................................................2-4
2-7 EB Series Scales Error Codes.............................................................................2-5
2-8 Membrane Switch Pin Connections.....................................................................2-6
2-9 Load Cell Resistance Reading.............................................................................2-7
2-10 Load Cell Output Reading....................................................................................2-8
3-1 Load Cell Screw Torque Settings.......................................................................3-11
3-2 Load Cell Overload Protection Stop Gap Settings..............................................3-13
4-1 Repeatability Worksheet......................................................................................4-2
4-2 Calibration Points.................................................................................................4-6
5-1 EB Series Scales: Housing and Parts..................................................................5-3
A-1 Scale Resolution Settings...................................................................................A-2
LIST OF ILLUSTRATIONS
FIGURE NO. TITLE Page No.
2-1 Membrane Switch Connector...............................................................................2-6
2-2 EB Interconnections: Version 1............................................................................2-8
2-3 EB Interconnections: Version 2............................................................................2-8
3-1 Retaining Screws on Bottom of Housing..............................................................3-1
3-2 Removing the Top Housing .................................................................................3-2
3-3 Ribbon Cable from Main PCB to Display PCB.....................................................3-2
3-4 Disconnecting the Membrane Switch Cable.........................................................3-3
3-5 Battery Terminal Connector.................................................................................3-4
3-6 Main PC Board Screws and Washers..................................................................3-4
3-7 Main PCB, Version 1 ...........................................................................................3-5
3-8 Main PCB, Version 2 ...........................................................................................3-5
3-9 Display Cable installed on Main PCB...................................................................3-5
3-10 Ribbon Cable from Main PCB to Display PCB.....................................................3-7
3-11 Disconnecting Membrane Switch Cable from Display PCB..................................3-7
3-12 Screws connecting Display PCB to Bottom Housing............................................3-7
3-13 Feet on Bottom of Scale ......................................................................................3-9
3-14 Load Cell Retaining Screw Locations...................................................................3-9
3-15 Load Cell Mounting Bolt Locations.....................................................................3-11
3-16 Load Cell Frame Mounting Bolt Locations .........................................................3-12

TABLE OF CONTENTS
EB Series Scales Service Manual iii Ohaus Corporation www.ohaus.com
FIGURE NO. TITLE Page No.
3-17 Overload Stop Locations....................................................................................3-12
3-18 Battery Connections ..........................................................................................3-14
4-1 Segment Display .................................................................................................4-1
4-2 Off-Center Load Test Weight Locations...............................................................4-2
5-1 EB Series Scales: Housing and Parts..................................................................5-2

TABLE OF CONTENTS
Ohaus Corporation www.ohaus.com iv EB Series Scales Service Manual

CHAPTER 1 GETTING STARTED
EB Series Scales Service Manual 1-1 Ohaus Corporation www.ohaus.com
1. INTRODUCTION
This service manual contains instructions for the diagnosis and repair work to be performed by
Ohaus Dealers or Ohaus authorized service centers. Knowledge of the operation of the Scale
is assumed. Instruction manuals may be required with this service manual. For complete
information on operation, refer to the Instruction Manual.
This manual covers maintenance on the following:
EB Series Scales, Models EB3, EB6, EB15 and EB30
The contents of this manual are contained in five chapters and two Appendixes with service
menu and calibration instructions.
Chapter 1 Introduction - Contains information about service facilities, tools, test equipment,
test masses, service strategy, specifications, and setup.
Chapter 2 Diagnosis - Contains information on problem verification, scale examination,
preliminary checks, troubleshooting tables, testing procedures, and an interconnection diagram.
Chapter 3 Repair Procedures - Contains detailed repair procedures for all major components.
Chapter 4 Final Testing - Contains performance tests, and calibration.
Chapter 5 Parts Lists - Contains overall views identifying all major serviceable replacement
components with associated parts lists.
Appendix A Service Modes- Contains Configuration, Capacity and Readability for the EB
Series Scales in a service mode.
Appendix B Service Calibration - Contains Service Calibration instructions.
1.1 SERVICE FACILITIES
To service a scale, the service area should meet the following requirements:
Meet scale specifications for temperature environmental requirements.
Be free of vibrations such as fork lift trucks close by, large motors, air currents or drafts
from air conditioning/heating ducts, open windows, people walking by, fans, etc.
Be clean and free of excessive dust.
Work surface must be stable and level.
Scale must not be exposed to direct sunlight or radiating heat sources.
Use an approved Electro-Static Device.

CHAPTER 1 GETTING STARTED
Ohaus Corporation www.ohaus.com 1-2 EB Series Scales Service Manual
1.2 TOOLS AND EQUIPMENT
1.2.1 Standard Tools and Test Equipment
The service shop should contain the following equipment:
1. Digital Voltmeter (DVM).
2. Standard Electronics tool kit.
3. Desk magnifier on a stand.
4. Grounding mat and clip.
5. Razor blades.
1.2.2 Special Tools
To service the Ohaus EB Series Scales, the following equipment is recommended:
1. A Load Cell Simulator.
2. AC Adapter, 220 V, 60 Hz (US) Ohaus P/N 80120000
3. AC Adapter, 230 V, 50 Hz (EU) Ohaus P/N 80120001
4. AC Adapter, 230 V, 50 Hz (GB) Ohaus P/N 80120002
5. AC Adapter, 240 V, 50 Hz (AU) Ohaus P/N 80120003
6. AC Adapter, 100 V, 50 Hz (JP) Ohaus P/N 80120004
7. AC Adapter, 230 V, 50 Hz (KR) Ohaus P/N 80120005
NOTE: Adapters required for servicing are location dependent.
1.3 CALIBRATION MASSES REQUIRED
The masses required to test the EB Series Scales must meet the requirements of ASTM Class
4 or OIML Class F2. The mass values are listed in Table 1-1.
TABLE 1-1. CALIBRATION MASSES
MODEL
Calibration Masses
Totaling
EB3
EB6
EB15
EB30
3kg
6kg
15kg
30kg
Note: The EB Scales can be calibrated over a wide range, however, it is recommended that the
calibration mass used is at or near the full capacity of the scale for maximum accuracy.
1.4 SERVICE STRATEGY
The repair method for the EB Series Scales is the direct substitution of major assemblies.
The available repair parts are listed in Table 5-1.
The EB Series Scales contain 6 major replaceable assemblies: Top Housing, Membrane
Switch, Load Cell Assembly with Frame, Lead Acid Rechargeable Battery, Display PC Board
with LCD and the Main PC Board.
Note: The Load Cell and LCD may also be ordered and replaced separately.

CHAPTER 1 GETTING STARTED
EB Series Scales Service Manual 1-3 Ohaus Corporation www.ohaus.com
1.5 SPECIFICATIONS
TABLE 1-2. SPECIFICATIONS
Model
EB3
EB6
EB15
EB30
Capacity x Readability
3 kg x 0.0001 kg
3000 g x 0.1 g
6.6 lb x 0.0002 lb
105 x 0.005 oz
6 kg x 0.0002 kg
6000g x 0.2g
13 lb x 0.0005 lb
208 x 0.01 oz
15 kg x 0.0005 kg
15000g x 0.5g
33 lb x 0.001 lb
528 x 0.02 oz
30 kg x 0.001 kg
30000g x 1g
66 lb x 0.002 lb
1,056 x 0.05 oz
Maximum Displayed
Resolution
1:30000
Construction
Stainless steel platform, plastic housing
Weighing Units
kg, g, lb, oz
Application Modes
Weighing, Counting, Hi-Lo Check-counting/weighing, Percent, Accumulation
Display
1-Window backlit LCD display, 25.4mm / 1” high, 6-digit, 7-segment
Display Indicators
Stability, Center of Zero, Gross, Tare, Battery Status, Hi-OK-Lo, Units
Keyboard
7-function membrane switch: M+, Units, Zero, Tare, Check, Count, %
Zero Range
4% of Full Scale Capacity
Tare Range
Full Capacity by Subtraction (except EB15: up to 10kg only)
Stabilization Time
< 2 seconds
Operating Temperature
0° to 40° C
Humidity Range
≤90% relative humidity, non-condensing
Power
AC Adapter 12V DC / 800mA
Internal rechargeable lead acid battery
Battery Life
80 hours continuous use with 12 hour recharge time
Calibration
Automatic external with kg/g mass, factory calibration recovery
Shipping Protection
Shipping screw to avoid damage to sensitive components
Safe Overload Capacity
120% of capacity
Platform Size
294 x 226 mm / 11.6 x 8.9 in.
Scale dimensions
325 x 330.5 x 114 mm / 12.8 x 13 x 4.5 in. (W x D x H)
Shipping dimensions
440 x 360 x 160 mm / 17.3 x 14.2 x 6.3 in (W x D x H)
Net Weight
4.2 kg / 9.3 lb
Shipping Weight
5.3 kg / 11.7 lb
Other Features
Auto-Zero Tracking, Filtering Level

CHAPTER 1 GETTING STARTED
Ohaus Corporation www.ohaus.com 1-4 EB Series Scales Service Manual
1.6 SCALE SETTINGS
The EB scale contains four user-selectable scale settings (Setup mode). These are as follows:
Scale Increment, Backlight, Zero Tracking Range, and Filtering. A description of each setting is
explained below.
1. To enter the setup mode, press and then release COUNT and M+ at the same time to
enter into the user-selectable scale settings.
2. In the Setup mode, press ▲to step through available settings.
3. Press Enter to accept the displayed setting and proceed to the next parameter.
4. Press Exit to proceed to the next parameter without saving any changes.
Table 1-3. MENU STRUCTURE
inC 01 EL AU AC 2d Fil 1
AU
ON
OFF
0.5d
1d
2d
4d
0
1
2
3
(Levels)
(d=scale division)
(mode-dependent
settings)
inC 01
EL AU
AC 2d
FiL 1
Scale increment - Sets the displayed scale increment (also known as readability or
graduation). Selectable setup values will be model dependent and are equivalent
to within 30,000 to 3,000 scale divisions.
Backlight - Sets the activation mode of the backlight.
The following settings are available: AU (Auto-on with items > 9d placed on the
Platform or any button pressed; turns off after 5 seconds of inactivity), On, oFF.
Zero Display Range - Sets the range in which the Zero reading is maintained.
The following settings are available: 0.5d, 1d, 2d, 4d (d= scale division).
Filtering - Sets the level at which the Stable indication turns on; the higher the
setting, the faster the stabilization time.
The following settings are available: 0, 1, 2, 3 (levels).

CHAPTER 2 DIAGNOSIS
EB Series Scales Series Service Manual 2-1 Ohaus Corporation www.ohaus.com
2. DIAGNOSIS
This section contains information needed to properly evaluate the reported problem and
diagnose its cause.
2.1 SCALE SETUP AND EXAMINATION
Set up the scale according to the Instruction manual. Allow the scale to stabilize to room
temperature. Examine the scale for signs of corrosion or physical damage.
2.2 PRELIMINARY CHECKS
Power up the scale using the customer’s ac adapter. In the case where the scale will not power
up, check the ac adapter. Observe and record the error codes and software revision.
Record all menu settings as received.
2.3 TROUBLESHOOTING TABLES
Troubleshooting tables 2-1 through 2-7 identify actual types of problems that could be
encountered with the scale.
The troubleshooting tables refer to the EB Scales Interconnection Diagram, Figure 2-2, to assist
in locating the problem.
TABLE 2-1. SCALE WILL NOT TURN ON WITH AC ADAPTER
SYMPTOM
PROBABLE CAUSE
REMEDY
Unit will not turn on
with AC adapter
supplied
Adapter defective
Membrane Switch defective
Check the AC adapter voltage output
(Section 2.5). If voltage is low or
nonexistent, replace the AC adapter.
If OK, proceed.
Test the Membrane Switch (Section
2.6). Replace if necessary
(Section 3.2).
If the scale fails to turn on with a new
Membrane Switch, test the Main PC
Board (Section 2.8). If defective,
replace the Main PCB (Section 3.3.1).
After repair, proceed with Performance
Tests in Chapter 4.

CHAPTER 2 DIAGNOSIS
Ohaus Corporation www.ohaus.com 2-2 EB Series Scales Series Service Manual
TABLE 2-2. SCALE WILL NOT TURN ON USING BATTERY POWER
SYMPTOM
PROBABLE CAUSE
REMEDY
Scale will not turn on
using battery power.
Battery discharged or
defective.
Wiring harness defective or
battery clips connection
broken.
Membrane Switch defective.
Main PC Board is defective.
Test the battery (Section 2.9). Replace
if necessary (Section 3.6).
Open the scale (Section 3.1). Check
voltage at battery contacts first. Check
DC voltage at the battery connector on
the Main PC Board. Voltage should
read approximately 6 Volts DC
minimum. If voltage is not present at
the connector, disconnect the leads
from the battery and make a continuity
test between the connectors on the
Harness to the connector on the Main
PC Board. Resistance should be 0
ohms for the red lead and 0 ohms for
the black lead. If an open condition
exists, replace wiring and connector as
necessary. If OK, proceed.
Test the Membrane Switch (Section
2.6). Replace if necessary
(Section 3.2).
If the scale fails to turn on with a new
Membrane Switch, test the Main PC
Board (Section 2.8). If defective,
replace the Main PCB (Section 3.3.1).
After repair, proceed with Performance
Tests in Chapter 4.

CHAPTER 2 DIAGNOSIS
EB Series Scales Series Service Manual 2-3 Ohaus Corporation www.ohaus.com
TABLE 2-3. SCALE DOES NOT RESPOND TO FRONT PANEL CONTROLS.
SYMPTOM
PROBABLE CAUSE
REMEDY
Scale does not
respond to front panel
controls.
Membrane Switch defective
Test the Membrane Switch (Section
2.6). Replace if necessary (Section
3.2). If membrane switches are OK,
test the Main PC Board (Section 2.8).
If defective, replace the Main PCB
(Section 3.3.1).
After repair, proceed with Performance
Tests in Chapter 4.
TABLE 2-4. NO DISPLAY OR PARTIAL DISPLAY.
SYMPTOM
PROBABLE CAUSE
REMEDY
Display is not on or
partial characters are
displayed.
Display PC Board is
defective or LCD may be
defective.
NOTE: If the LCD shows
signs of damage such as
cracked, dim or partial
characters, the LCD should
be replaced.
The Display PC Board is replaced as a
whole assembly. Check procedures in
Tables 2-1, 2-2 and 2-3 first and verify
that other problems do not exist.
Replace Display PC Board or LCD.
See Repair Procedures 3.3.2 and
3.3.3.
After repair, proceed with Performance
Tests in Chapter 4.

CHAPTER 2 DIAGNOSIS
Ohaus Corporation www.ohaus.com 2-4 EB Series Scales Series Service Manual
TABLE 2-5. BALANCE READING INCORRECT OR UNSTABLE.
SYMPTOM
PROBABLE CAUSE
REMEDY
Balance reads
incorrectly.
Balance reading
unstable.
Needs calibration.
Load Cell is damaged.
Main PC Board defective.
Perform Service Calibration in
Appendix B. If calibration fails, refer to
Table 2-6.
Test the Load Cell (Section 2.7). If
defective replace it (Section 3.4).
After repair, proceed with Performance
Tests in Chapter 4.
Test the Main PC Board (Section 2.8).
If defective, replace it (Section 3.3).
After repair, proceed with Performance
Tests in Chapter 4.
TABLE 2-6. CANNOT CALIBRATE THE SCALE.
SYMPTOM
PROBABLE CAUSE
REMEDY
Scale can be turned
on but will not
calibrate.
Incorrect weights.
Load cell assembly
defective.
Main PC Board defective
Verify that proper weights are used.
Test the Load Cell (Section 2.7). If
defective replace it (Section 3.4).
After repair, proceed with Performance
Tests in Chapter 4.
Test the Main PC Board (Section 2.8).
If defective, replace it (Section 3.3).
After repair, proceed with Performance
Tests in Chapter 4.

CHAPTER 2 DIAGNOSIS
EB Series Scales Series Service Manual 2-5 Ohaus Corporation www.ohaus.com
2.4 EB SERIES SCALES ERROR CODE TABLE
The EB Series Scales is equipped with software which will display an error condition when it
occurs. Review the listed codes and follow instructions to correct the problem.
TABLE 2-7. EB SERIES SCALES ERROR CODES
ERROR CODE
PROBABLE CAUSE
REMEDY
E1, E2, E3
displayed
The pan is placed incorrectly.
Zero limit exceeded during
power up.
Load Cell Assembly Defective.
Main PC Board defective
Reposition the Pan correctly.
Ensure the Pan is empty before
switching the scale on.
Test the Load Cell (Section 2.7). If
defective replace it (Section 3.4).
After repair, proceed with Performance
Tests in Chapter 4.
Test the Main PC Board (Section 2.8).
If defective, replace it (Section 3.3).
After repair, proceed with Performance
Tests in Chapter 4.
--OL—
displayed
Load exceeds scale capacity.
Load cell defective.
Main PCB is defective.
Reduce the load on the Pan.
Test the Load Cell (Section 2.7). If
defective replace it (Section 3.4).
After repair, proceed with Performance
Tests in Chapter 4.
Test the Main PC Board (Section 2.8).
If defective, replace it (Section 3.3).
After repair, proceed with Performance
Tests in Chapter 4.

CHAPTER 2 DIAGNOSIS
Ohaus Corporation www.ohaus.com 2-6 EB Series Scales Series Service Manual
2.5. TESTING THE AC ADAPTER
The AC Adapters are available with different input voltages. Before testing the Adapter, make
sure the Adapter rating agrees with the power source being used. All Adapters are rated with an
output of 12 V dc at 800mA. Adapters can fail by having shorted internal windings producing low
voltage output or no output at all.
1. Plug the AC Adapter in a suitable power source and measure the open circuit voltage on
connector it should be 10 V dc to 16 V dc.
2. Refer to Section 4.1 and remove the Top Housing. Plug the AC Adapter into the scale
and measure the voltage on the battery terminals. Turn the scale on. The voltage should
be 6.5 Volts dc minimum, and 7.5 Volts dc maximum. If the voltage is below or above
these readings, replace the Adapter. This is the actual battery voltage while charging.
2.6 TESTING THE MEMBRANE SWITCH
The Membrane Switch can be tested after removing the Top Housing from the Bottom Housing.
1. Refer to Section 4.1 and remove the Top Housing.
2. Disconnect the Membrane Switch connector from the Display PCB.
3. Refer to Table 3-1. Using an Ohmmeter, measure the resistance between the pins
shown in the table. The readings should be less than 70 Ohms for each button. If
continuity is not present or the resistance is higher than 100 Ohms, the Membrane
Switch is defective. Replace the Membrane Switch. Figure 3-1 illustrates the cable
connector and pin locations.
4. Reassemble Top Housing to Bottom Housing.
TABLE 2-8. MEMBRANE SWITCH PIN CONNECTIONS.
PANEL BUTTON
PINS
Figure 2-1. Membrane Switch Connector.
M+
1 to 2
UNITS
1 to 3
ZERO
1 to 4
TARE
1 to 5
CHECK
1 to 6
COUNT
1 to 7
%
1 to 8

CHAPTER 2 DIAGNOSIS
EB Series Scales Series Service Manual 2-7 Ohaus Corporation www.ohaus.com
2.7 TESTING THE LOAD CELL ASSEMBLY
This section contains two methods of testing the Load cell.
2.7.1 Resistance Test
1. Refer to Section 3.1 and remove the Top Housing.
2. Refer to Figure 3-2 and record color code and position of the wires from the Load
Cell.
3. Unsolder the Load Cell cable from the Main PC Board. Using an Ohmmeter,
measure in accordance with Table 2-9 Load Cell Resistance Readings on the cable.
If the resistance readings vary more than the table readings allow, replace the Load
Cell in accordance with the procedure in Section 3.4 or 3.5. This resistance test is
useful in determining if the Load Cell has been severely damaged by a short or open
circuit which has occurred on the cell or wiring. If the Load Cell resistance readings
are good, continue with this procedure.
TABLE 2-9. LOAD CELL RESISTANCE READING.
MEASUREMENT POINTS
READING
WIRES 2 & 5
415 ±15 Ohms
WIRES 3 & 4
350 ±3 Ohms
NOTE: Wires 2, 3, 4 and 5 must be isolated from chassis ground and shield.
Resistance should be greater than 5 megohms. A lower reading indicates a short in
either in the Load Cell cable or the Load Cell.
4. Reconnect Load cell cable to the Main PCB.
2.7.2 Excitation and Output Voltage Test
Notes:
–The following steps involve power applied to the scale.
–Load Cell solder contacts can be used as measuring points. See Figure 2-2.
1. Insert the Pan Support into the Load Cell Frame and place the Pan on top.
2. Turn on power to the scale.
3. With no load on the Pan, first measure the excitation voltage across point 2 and 5
Load Cell connection on the PCB. This voltage must be 5.0 Volts dc with the Load
cell connected. If the voltage is lower, disconnect the Load Cell cable from the PC
Board and measure again. If the voltage is 5 Volts dc, the Load Cell is defective and
must be replaced. If the voltage remains low, the PC Board is defective and the Main
PC Board must be replaced. For Main PC Board replacement, see Section 4.3.
4. Refer to Figure 2-2 and measure the voltages on points 3 and 4, +SIG and –SIG
points. These measurements represent the output of the Load Cell. Repeat
measurements at 50% and full scale capacities. See Table 2-10 for typical readings.

CHAPTER 2 DIAGNOSIS
Ohaus Corporation www.ohaus.com 2-8 EB Series Scales Series Service Manual
2.7.2 Excitation and Output Voltage Test continued
Note: Table 2-10 indicates typical readings. Actual values can vary, but should remain
linear throughout the entire range.
If readings are out of tolerance, replace the Load Cell. See Section 3.4 or 3.5 for Load Cell
replacement. TABLE 2-10. LOAD CELL OUTPUT READING.
NOMINAL OUTPUT IN MILLIVOLVTS AT 5 VOLTS EXCITATION
CAPACITY
NO LOAD
50%
100%
3 kg
6 kg
15 kg
30 kg
2.7 ±1.5
1.9 ±1.5
1.2 ±1.5
0.5 ±1.5
no load + 3.2
no load + 4.4
no load + 5.2
no load + 4.9
no load + 6.4
no load + 8.8
no load + 10.3
no load + 10.4
Note: Wiring connections are different
in Version 1 and Version 2.
(V2 introduced in Fall 2009.)
AC ADAPTER
CONNECTOR
TO POWER
SWITCH
Main PCB: VERSION 1
Figure 2-2. EB Interconnections: Version 1.
Note: Wiring connections are different
in Version 1 and Version 2.
(V2 introduced in Fall 2009.)
Main PCB: VERSION 2 AC ADAPTER
CONNECTOR
TO POWER
SWITCH
Figure 2-3. EB Interconnections: Version 2.