OHAUS EB3 Service Manual
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OHAUS EB3 Service Manual

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EB SERIES SCALES
SERVICE MANUAL
99 Washington Street
Melrose, MA 02176
Phone 781-665-1400
Toll Free 1-800-517-8431
Visit us at www.TestEquipmentDepot.com

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  • Page 1 99 Washington Street Melrose, MA 02176 Phone 781-665-1400 Toll Free 1-800-517-8431 Visit us at www.TestEquipmentDepot.com EB SERIES SCALES SERVICE MANUAL...
  • Page 3 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.

  • Page 5: Table Of Contents

    TABLE OF CONTENTS CHAPTER 1 INTRODUCTION Page Introduction ...................... 1-1 Service Facilities ....................1-1 Tools and Equipment ..................1-2 1.2.1 Standard Tools and Test Equipment ............1-2 1.2.2 Special Tools................... 1-2 Calibration Masses Required ................1-2 Service Strategy ....................1-2 CHAPTER 2 DIAGNOSIS Diagnosis ......................
  • Page 6 TABLE OF CONTENTS (Cont.) CHAPTER 4 REPAIR PROCEDURES Page Repair Procedures ....................4-1 Removing Top Housing ..................4-1 Replacing the Membrane Switch ................4-2 Main PC Board ....................4-4 4.3.1 Main PC Board Replacement ..............4-4 4.3.2 Display PC Board Replacement ..............4-7 4.3.3 LCD Replacement ..................

  • Page 7: Chapter 1 Introduction

    CHAPTER 1 INTRODUCTION 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 EB Scale is assumed. Instruction manuals may be required with this service manual. For complete information on operation, refer to the Instruction Manual.

  • Page 8: Tools And Equipment

    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.

  • Page 9: Chapter 2 Diagnosis

    CHAPTER 2 DIAGNOSIS 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.
  • Page 10 CHAPTER 2 DIAGNOSIS TABLE 2-2 SCALE WILL NOT TURN ON USING BATTERY POWER. SYMPTOM PROBABLE CAUSE REMEDY Scale will not turn on using Refer to Section 3.5 and test the battery. Battery discharged or de- battery power. fective. Replace if necessary. See Repair Proce- dure 4.6.
  • Page 11 CHAPTER 2 DIAGNOSIS TABLE 2-3 SCALE DOES NOT RESPOND TO FRONT PANEL CONTROLS. PROBABLE CAUSE REMEDY SYMPTOM Membrane Switch is defec- Refer to Section 3.2 and test the Mem- Scale does not respond to front tive. brane switch. Replace if necessary. panel controls.
  • Page 12 CHAPTER 2 DIAGNOSIS TABLE 2-5 SCALE READING INCORRECT OR UNSTABLE. SYMPTOM REMEDY PROBABLE CAUSE Perform Service Calibration in Appen- Scale reads incorrectly. Needs calibration. dix A. If calibration fails, refer to Table 2-6. Test the Load Cell, refer to Section 3.3. Scale reading unstable.

  • Page 13: Eb Series Scales Error Code Table

    CHAPTER 2 DIAGNOSIS 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 REMEDY CAUSE ERROR CODE...
  • Page 14 CHAPTER 2 DIAGNOSIS...

  • Page 15: Chapter 3 Scale Testing And Calibration

    CHAPTER 3 SCALE TESTING AND CALIBRATION 3. TESTING AND CALIBRATION This section of the manual contains testing procedures of the individual replaceable components and the scale. Before and after servicing the EB Series Scales, an operational test and various performance tests should be made to ascertain whether or not the scale meets specifications.

  • Page 16: Testing The Load Cell Assembly

    CHAPTER 3 SCALE TESTING AND CALIBRATION 3.3 TESTING THE LOAD CELL ASSEMBLY This section contains two methods of testing the Load cell. 3.3.1 Resistance Test 1. Refer to Section 4.1 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.
  • Page 17 CHAPTER 3 SCALE TESTING AND CALIBRATION 3.3.2 Excitation and Output Voltage Test (Cont.) 4. Refer to Figure 3-2 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.

  • Page 18: Testing The Main Pc Board

    CHAPTER 3 SCALE TESTING AND CALIBRATION 3.4 TESTING THE MAIN PC BOARD The Main PC Board can be tested by measuring voltages and by using a simulator. The simulator replaces the Load Cell during testing and is a useful tool for diagnosing problems. 3.4.1 Main PC Board Voltage Measurements Prior to making the voltage measurements, the battery should have been fully charged and tested.

  • Page 19: Simulator Testing

    CHAPTER 3 SCALE TESTING AND CALIBRATION 3.4.2 Simulator Testing To perform these tests, the use of a Simulator is required. The basic function of a Simulator is to simulate the output of a full bridge Load Cell allowing the scale to be separated from the Load Cell for the purposes of troubleshooting and calibration.

  • Page 20: Testing The Battery

    CHAPTER 3 SCALE TESTING AND CALIBRATION Calibration Test (Cont.) 3. Upon completion of calibration, the Main PC Board can be further checked using the Simulator to simulate various weight values. If simulator settings and weight reading on the scale agree, the Main PC Board is functional.
  • Page 21 CHAPTER 3 SCALE TESTING AND CALIBRATION 3.5.2 Battery Tests (cont.) 3. With the AC Adapter connected, measure the battery voltage at the battery terminals; the voltage should be approximately 6 to 7 Volts dc when charging. The voltage should be above 6.0 Volts dc ten minutes after charging stops.

  • Page 22: Performance Tests

    Each scale tested must meet the requirements specified in each test as well as the specifications listed in Table 3-4. A scale passing each of these three tests complies with Ohaus specifications. A segment display test determines if the display is working properly. 3.6.1 Segment Display Test Connect the AC Adapter into a suitable power source and connect it to the scale.
  • Page 23 CHAPTER 3 SCALE TESTING AND CALIBRATION 3.6.2 Repeatability Test (Cont.) Test Procedure: 1. Zero the scale. 2. Using a test mass approximately 1/2 the capacity of the scale, place the mass on the center of platform. Record the reading on the worksheet provided. 3.

  • Page 24: Off-Center Load Test

    CHAPTER 3 SCALE TESTING AND CALIBRATION 3.6.3 Off-Center Load Test The Off-Center Load Test is used to determine whether displayed weight values will be affected by moving the sample to different areas of the weighing surface. See Figure 3-4. This test must be performed using a single mass or the masses must be stacked. 1.

  • Page 25: Linearity Test

    CHAPTER 3 SCALE TESTING AND CALIBRATION 3.6.4 Linearity Test The linearity test is used to determine the linearity of the scale throughout its operating range. The results should be in accordance with the specifications shown above. The reference mass should be approxi- mately 1/8 of the full-capacity of the scale.
  • Page 26 CHAPTER 3 SCALE TESTING AND CALIBRATION 3.6.4 Linearity Test (cont.) Record Readings Reading 1 reference weight added to zero ________________ Reading 2 reference weight added at 1/4 full-scale capacity ________________ Reading 3 reference weight added at 1/2 full-scale capacity ________________ Reading 4 reference weight added at 3/4 full-scale capacity ________________ Calculate Differences Reading 1 –...

  • Page 27: Specifications

    CHAPTER 3 SCALE TESTING AND CALIBRATION 3.7 SPECIFICATIONS TABLE 3-4. EB SCALE SPECIFICATIONS. Model EB15 EB30 Capacity x Readability 3 kg x 0.0001 kg 6 kg x 0.0002 kg 15 kg x 0.0005 kg 30 kg x 0.001 kg 3000 g x 0.1 g 6000 g x 0.2 g 15000 g x 0.5 g 30000 g x 1 g...

  • Page 28: Calibration

    CHAPTER 3 SCALE TESTING AND CALIBRATION 3.8 CALIBRATION Calibration – The EB Series’ calibration can be calibrated using full scale capacity as the best method for the most accurate results, this is referred to as span calibration. Calibration Weights – Before beginning calibration, make sure that the required calibration weights are available.

  • Page 29: Scale Settings

    CHAPTER 3 SCALE TESTING AND CALIBRATION 3.9 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.
  • Page 30 CHAPTER 3 SCALE TESTING AND CALIBRATION 3-16...

  • Page 31: Chapter 4 Repair Procedures

    CHAPTER 4 REPAIR PROCEDURES REPAIR PROCEDURES This section describes how to change individual components of the EB Series Scales. When doing this, please refer to the drawings and parts lists in Section 5. Important: After replacing components, an operational test of the scale must always be carried out, (see Section 3.6).

  • Page 32: Replacing The Membrane Switch

    CHAPTER 4 REPAIR PROCEDURES REPLACING THE MEMBRANE SWITCH The membrane switch is affixed to the Top Housing of the scale. To replace the Membrane Switch, the scale must be disassembled to gain access to the switch connections. 1. Refer to Section 4.1 and remove Top Housing. CAUTION Use care in the next step as the Display PCB wiring is attached to the PC board.
  • Page 33 CHAPTER 4 REPAIR PROCEDURES REPLACING THE MEMBRANE SWITCH (Cont.) 4. Disconnect the Membrane Switch Cable from the Display PCB as shown in Figure 4-4. Figure 4-4. Disconnecting the Membrane Switch Cable. 5. On the Top Housing, lift up the defective Membrane Switch (if necessary carefully prying it up with a knife) and gently peel it off the Top Housing.

  • Page 34: Main Pc Board

    CHAPTER 4 REPAIR PROCEDURES MAIN PC BOARD The Main PC Board is located in the Bottom Housing. To replace the Main PC Board, it is necessary to disassemble the scale. 4.3.1 Main PC Board Replacement 1. Refer to Section 4.1 and remove the Top Housing. 2.
  • Page 35 CHAPTER 4 REPAIR PROCEDURES 4.3.1 Main PC Board Replacement (Cont.) 6. Remove the Battery connector plug from the Main PC Board and the connector that connects to the On/Off Switch. See Figure 4-7. LOAD CELL WIRING BATTERY CONNECTOR ON/OFF SWITCH CONNECTOR Figure 4-7.
  • Page 36 CHAPTER 4 REPAIR PROCEDURES 4.3.1 Main PC Board Replacement (Cont.) 11. Install the Main PC Board into position in the slots on the Bottom Housing and secure with the screws and washers previously removed. 12. Connect the Battery connector to the Battery. NOTE: When a replacement Main PC Board is installed, the scale must be put into a service mode first to enter parameters such as capacity and readability.

  • Page 37: Display Pc Board Replacement

    CHAPTER 4 REPAIR PROCEDURES 4.3.2 Display PC Board Replacement 1. Refer to Section 4.1 and remove the Top Housing. 2. Disconnect the Ribbon Cable from the Display PC board. See Figure 4-10. Figure 4-10. Disconnecting the Ribbon Cable. 3. Disconnect the Membrane Switch Cable from the Display PC Board. See Figure 4-11. Figure 4-11.

  • Page 38: Lcd Replacement

    CHAPTER 4 REPAIR PROCEDURES 4.3.2 Display PC Board Replacement (Cont.) 6. Install the replacement Display PC board with the screws previously removed. 7. Connect the Membrane Switch Cable from the Top Housing to the Display PC Board and the Ribbon Cable from the Main PC Board to the Display PC Board.

  • Page 39: Replacing The Load Cell Assembly (With Frame)

    CHAPTER 4 REPAIR PROCEDURES REPLACING THE LOAD CELL ASSEMBLY (WITH FRAME) The Load Cell Assembly is centrally located inside the scale. The Load Cell is factory assembled and the overload protection stops are installed. The overload protection stops should be checked before installation.
  • Page 40 CHAPTER 4 REPAIR PROCEDURES REPLACING THE LOAD CELL ASSEMBLY (WITH FRAME) (Cont.) 5. Refer to Section 4.5.1 and check overload stops on the new assembly. 6. Lift the Load Cell Assembly out of the Bottom Housing and replace with the new one. Install screws. 7.

  • Page 41: Replacing The Load Cell Component

    CHAPTER 4 REPAIR PROCEDURES REPLACING THE LOAD CELL COMPONENT This procedure is used when it is desired to keep the existing Load Cell Frame and replace only the Load Cell. The Load Cell Assembly is centrally located inside the scale. When the new Load Cell is mounted to the existing Frame, the Overload Protection Stops must be adjusted.

  • Page 42: Overload Protection Stop Adjustment

    CHAPTER 4 REPAIR PROCEDURES REPLACING THE LOAD CELL COMPONENT (Cont.) 7. Position the Load Cell and Frame in the Bottom Housing and install the four retaining screws through the Frame into the Bottom Housing. See Figure 4-17. RETAINING SCREW TIE WRAP Figure 4-17.

  • Page 43: Replacing The Battery

    CHAPTER 4 REPAIR PROCEDURES 4.5.1 Overload Protection Stop Adjustment (Cont.) 3. Add the mass specified in Table 4-2. The mass should be placed on the center of the Platform. With the specified mass on the Platform, all of the overload (down) stops should hit the bottom Load Cell Frame.
  • Page 44 CHAPTER 4 REPAIR PROCEDURES REPLACING THE BATTERY (Cont.) 2. Disconnect the two wires from the battery. See Figure 4-19 which is a close-up view of the battery. Figure 4-19. Battery Connections. 3. Remove the Battery from the Bottom Housing. 4. Install a replacement Battery into the same position as the original Battery. The positive terminal (Red) should be facing up.

  • Page 45: Chapter 5 Parts Lists

    If further technical information is needed, in the United States call toll-free 1-800-526-0659 between 8.00 a.m. and 4.00 p.m. EST. An Ohaus factory service technician will be available to provide assistance. Outside the U.S.A., please visit our site www.Ohaus.com to locate the nearest Ohaus office.

  • Page 46: Eb Series Scales Components

    CHAPTER 5 PARTS LISTS 5.1 EB Series Scales Components PLATFORM (P/N 80120009) PLATFORM SUPPORT TOP HOUSING (P/N 80120007) (P/N 80104205) TOP HOUSING OPEN (P/N 80104203) DISPLAY PCB (P/N 80104191) MEMBRANE SWITCH (P/N 80251386) FRONT OVERLAY (P/N 80251391 EBJP) (P/N 80251385) EB SCALE FULLY ASSEMBLED FEET (P/N 80120032) - 1 Pc...
  • Page 47 CHAPTER 5 PARTS LISTS 5.1 EB Series Scales Components (Cont.) LOADCELL BATTERY (P/N 80120013, EC3) (P/N 80120014, EC6) (P/N 80120026) (P/N 80120015, EC15) (P/N 80120016, EC30) LOADCELL ASSEMBLY LOAD CELL TOP FRAME (P/N 80120017, EC3) (P/N 80120039) (P/N 80120018, EC6) (P/N 80120019 EC15) (P/N 80120020, EC30) LOAD CELL...
  • Page 48 CHAPTER 5 PARTS LISTS TABLE 5-1. EB SERIES SCALES PARTS LIST. PART NO. DESCRIPTION 80120000 Adapter, US, 120V, 80120001 Adapter, EU, 230V, 80120002 Adapter, GB, 230V, 80120003 Adapter, AU, 240V, 80120004 Adapter, JP, 100V, 80251386 Switch, Membrane 80251391 Switch, Membrane, EBJP 80120007 Platform support 80120009...

  • Page 49: Appendix A Eb Service Modes/Service Calibration

    APPENDIX A EB SERVICE MODES/SERVICE CALIBRATION A. EB SERVICE MODES This Appendix describes the Service menu and sub-menus, which allow authorized service personnel to configure the EB scale. Configuration settings include setting the capacity and resolution and setting the decimal point position. ENTERING THE SERVICE MENU 1.

  • Page 50: Scale Configuration

    APPENDIX A EB SERVICE MODES/SERVICE CALIBRATION SERVICE CALIBRATION (Cont.) 3. Add the displayed weight and wait until the display shows the third weight to add (full capacity). 4. After accepting the weight, the scale will restart the scale check process. Remove the weight while the self-check is occurring.
  • Page 52 *80251392* PN 80251392 A SERVICE MANUAL - EB SERIES SCALES Test Equipment Depot - 800.517.8431 - 99 Washington Street Melrose, MA 02176 - TestEquipmentDepot.com...

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