OHAUS EC SERIES Service Manual
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OHAUS EC SERIES Service Manual

OHAUS EC SERIES Service Manual

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EC SERIES SCALES
SERVICE MANUAL
Ohaus Corporation 19A Chapin Road, P.O. Box 2033, Pine Brook, NJ 07058 (973) 377-9000

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  • Page 1 EC SERIES SCALES SERVICE MANUAL Ohaus Corporation 19A Chapin Road, P.O. Box 2033, Pine Brook, NJ 07058 (973) 377-9000...
  • 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

    ...................... 2-1 Scale Setup and Examination ................2-1 Preliminary Checks ..................... 2-1 Troubleshooting Tables ..................2-1 EC Series Scales Error Code Table................2-5 CHAPTER 3 SCALE TESTING AND CALIBRATION Testing and Calibration ..................3-1 Testing the AC Adapter ..................3-1 Testing the Membrane Switch ................
  • Page 6 4.5.1 Overload Protection Stop Adjustment ............4-12 Replacing the Battery ..................4-13 CHAPTER 5 PARTS LISTS Parts Lists ...................... 5-1 EC Series Scales Components ................5-2 APPENDIX A SERVICE MODES Introduction ...................... A-1 Entering Service Menu ..................A-1 Select Weight Units ..................... A-1 Select Display Increment ..................

  • Page 7: Chapter 1 Introduction

    Chapter 5 Parts Lists - Contains overall views identifying all major serviceable replacement components with associated parts lists. Appendix A Service Modes - Contains Capacity and Readability for the EC Series Scales in a service mode. Appendix B Service Calibration - Contains Service Calibration instructions.

  • Page 8: Tools And Equipment

    NOTE: Adapters required for servicing are location dependent. 1.3 CALIBRATION MASSES REQUIRED The masses required to test the EC Series Scales must meet the requirements of ASTM Class 4 or OIML Class F2. The mass values are listed in Table 1-1.

  • 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 Battery discharged or de- Refer to Section 3.5 and test the battery. 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 BALANCE READING INCORRECT OR UNSTABLE. SYMPTOM REMEDY PROBABLE CAUSE Perform Service Calibration in Appen- Balance reads incorrectly. Needs calibration. dix B. If calibration fails, refer to Table 2-6. Test the Load Cell, refer to Section 3.3. Balance reading unstable.

  • Page 13: Ec Series Scales Error Code Table

    CHAPTER 2 DIAGNOSIS 2.4 EC SERIES SCALES ERROR CODE TABLE The EC 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. EC SERIES SCALES ERROR CODES...
  • Page 14 CHAPTER 2 DIAGNOSIS...

  • Page 15: Chapter 3 Scale Testing And Calibration

    This section of the manual contains testing procedures of the individual replaceable components and the scale. Before and after servicing the EC 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 1.9 +1.5 no load + 4.4 no load + 8.8 15 kg 1.2 +1.5 no load + 5.2 no load + 10.3 30kg 0.5 +1.5 no load + 4.9 no load + 10.4 Figure 3-2. EC Series Scales Interconnection Diagram.

  • 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

    If left connected to the AC Adapter all of the time, the battery receives a small charge when the battery voltage is low, service life can be many years. The EC Series Scales can be operated for up to 80 hours per charge. Battery life can be maximized by frequent charging.
  • 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

    CHAPTER 3 SCALE TESTING AND CALIBRATION 3.6 PERFORMANCE TESTS Accurate performance of the EC Series Scales is determined by a series of three performance tests, Repeatability Test, Off-Center Load Test and Linearity Test. These tests are used to evaluate the scale performance before and after repairs.
  • 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. EC SCALE SPECIFICATIONS. Model EC15 EC30 Capacity x Readability 3000 g x 0.1 g 6000 g x 0.2 g 15000 g x 0.5 g 30000 g x 1 g 6 lb x 0.0002 lb 15 lb x 0.0005 lb 30 lb x 0.001 lb 60 lb x 0.002 lb...

  • Page 28: Calibration

    CHAPTER 3 SCALE TESTING AND CALIBRATION 3.8 CALIBRATION Calibration – The EC 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 EC scale contains eight user-selectable scale settings (Setup mode). These are as follows: Auto-Off, Zero Tracking Range, Zero Display Range, Filtering, Zero Return Range, Backlight, Unit selection and APW Re-computing. A description of each setting is explained below. 1.
  • 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 EC 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 six 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 Pan. With the specified mass on the Pan, 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

    CHAPTER 5 PARTS LISTS 5. PARTS LISTS This section of the manual contains exploded views, and parts lists for the EC Series Scales. The exploded view drawings identify the replaceable parts. NOTE: In all cases where a part is replaced, the scale must be thoroughly checked after the replacement is made.

  • Page 46: Ec Series Scales Components

    (P/N 80120032) - 1 Pc ADAPTER (P/N 80120000, US) (P/N 80120001, EU) (P/N 80120002, GB) (P/N 80120003, AU) HARDWARE KIT (P/N 80120004, JP) (P/N 80120031) (P/N 80120025, KR) BOTTOM HOUSING (P/N 80120024) Figure 5-1. Major Components of EC Series Scales.
  • Page 47 MAIN PCB (P/N 80104177) Scales older than SN 8026532998 require a new Display PCB POWER ON/OFF SWITCH (P/N 801200021) DISPLAY CABLE BOTTOM HOUSING OPEN (P/N 80120022) BUBBLE LEVEL (P/N 80120042) Figure 5-2. Components in Bottom Housing of EC Series Scales.
  • Page 48 CHAPTER 5 PARTS LISTS TABLE 5-1. EC 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, 80120005 Switch, Membrane 80010589 Switch, Membrane, ECJP...

  • Page 49: Appendix A Service Modes

    APPENDIX A SERVICE MODES A. INTRODUCTION This Appendix describes the Service menu and sub-menus, which allow authorized service personnel to configure the scale. Configuration settings include selecting a weighing unit either grams (g) or kilograms (kg), setting the display increment, setting the capacity and resolution and setting the decimal point position.

  • Page 50: Select Display Increment

    APPENDIX A SERVICE MODES TABLE A-1. MODEL CONFIGURATION SETTING. MODEL 30000 3000.0 60000 6000.0 EC15 150000 15000.0 EC30 30000 30000. A.3 SELECT DISPLAY INCREMENT See Table A-1. The last digit of the weigh display (left window) will increment by the number of divisions 1, 2 or 5 as selected.

  • Page 51: Select Decimal Point Position

    APPENDIX A SERVICE MODES A.5 SELECT DECIMAL POINT POSITION See Table A-1. 1. The center display shows dot. 2. Press Sample repeatedly to select decimal point position. Refer to figure A-1 for values. 3. Press Tare to accept setting and advance. Figure A-6 illustrates two samples. Figure A-6.
  • Page 52 APPENDIX A SERVICE MODES...

  • Page 53: Introduction

    APPENDIX B SERVICE CALIBRATION B. INTRODUCTION This Appendix describes the Service calibration for the EC scale and allows authorized service personnel to calibrate the scale. Service calibration is used when normal calibration fails or a Load Cell or Main PC Board has been changed.
  • Page 54 APPENDIX B SERVICE CALIBRATION B.1 CALIBRATION (Cont.) 9. Add the third weight to the total indicated on the scale (3000g shown), then wait. See Figure B-4. Figure B-4. Third Calibration Weight Display. 10. When calibration is complete, the weight is indicated in the first window, center and right windows indicate 0.
  • Page 56 *80010584* PN 80010584 B SERVICE MANUAL - EC SERIES SCALES...

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