OHAUS DISCOVERY BALANCE Service Manual
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OHAUS DISCOVERY BALANCE Service Manual

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

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  • Page 1 SERVICE MANUAL DISCOVERY BALANCE Ohaus Corporation 19A Chapin Road, P.O. Box 2033, Pine Brook, NJ 07058-2033 (973) 377-9000...
  • Page 3 SERVICE MANUAL DISCOVERY BALANCE 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

    RS232 Commands .....................4-8 Print Test ........................4-9 Testing the AC Adapter .....................4-9 CHAPTER 5 PARTS LISTS & DIAGRAMS Discovery Housing.....................5-1 Discovery Display Assembly..................5-2 Discovery Internal Parts Outside Load Cell ...............5-3 Discovery Load Cell Parts ..................5-4 Ohaus Corporation www.ohaus.com Discovery Balance Service Manual...
  • Page 6 C.5.1 Incal Weight Mechanism Testing............... C-6 LIST OF TABLES TABLE NO. TITLE Masses Used to Test Discovery Balance..............1-3 Discovery Balance Model Specifications...............1-4 Balance Will Not Turn On..................2-2 Balance Does Not Respond to Front Panel Controls ..........2-3 No Display or Partial Display.................2-3 Balance Cannot Calibrate Using External Weights ..........2-4...
  • Page 7 LIST OF ILLUSTRATIONS (Cont.) FIGURE NO. TITLE Page No. Scale drawing of Discovery Balance Display Parts ..........3-5 Removing screws to separate Display Housing from bottom of balance ....3-6 Display Balance Load Cell Cover................3-7 3-10 Discovery Balance Printed Circuit Board (PCB)............3-8 3-11 EEProm chip, next to battery on main PCB ............3-8...
  • Page 8 Load Cell with Cover in proper position, cables resting in notches .....3-46 3-95 Placing PCB Mounting Plate on Load Cell ............3-47 3-96 Stand-off screws secure PCB Mounting Plate ............3-47 3-97 Installing Weights and Weight Holders..............3-48 Ohaus Corporation www.ohaus.com Discovery Balance Service Manual...
  • Page 9 Correct position of Display Cable under Display Cable Shield Plate ....3-49 3-101 Securing PCB Cover ...................3-50 LCD Full Display for Discovery Balance..............4-1 Holes in back cover must be popped out to insert Allen Keys ......4-3 Ohaus engineer demonstrates adjusting Off-Center Load........4-3 Allen key rotation directions needed for back-edge-heavy, back-edge-light, right-edge-heavy and right-edge-light conditions......4-4...
  • Page 10 TABLE OF CONTENTS Ohaus Corporation www.ohaus.com Discovery Balance Service Manual...

  • Page 11: Chapter 1 Introduction

    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. • Use an approved Electro-Static Device. Discovery Balance Service Manual Ohaus Corporation www.ohaus.com...

  • Page 12: Special Tools And Test Equipment Required

    7. Digital Voltmeter (DVM) Input impedance of at least 10 megohms in the 1 Volt DC position. 8. Masses as shown in Table 1.4. These masses are available from any Ohaus dealer. 9. Discovery Software Service Tool, P/N 80104129 Ohaus Corporation www.ohaus.com...

  • Page 13: Test Masses Required

    SPAN CALIBRATION POINTS WEIGHT CLASS MODEL CAPACITY (g) DEFAULT ALTERNATE ASTM OIML CAL POINTS (g) CAL POINTS (g) Class 1 DV114C Class 1 DV214C Class 1 DV314C 100, 200 Class 1 DV215CD 81/210 Discovery Balance Service Manual Ohaus Corporation www.ohaus.com...

  • Page 14: Specifications

    CHAPTER 1 INTRODUCTION SPECIFICATIONS Specifications for the Discovery Balances are listed in Table 1-2. After a balance has been serviced, it must meet the specifications listed in the table. Table 1-2. DISCOVERY BALANCE MODEL SPECIFICATIONS Model Number DV 114C DV 214C...

  • Page 15: Chapter 2 Diagnosis

    If more than one symptom is observed, approach one area at a time, and remember that the symptoms may be interrelated. If a problem arises that is not covered in this manual, contact Ohaus Corporation for further information. Discovery Balance Service Manual...

  • Page 16: Balance Will Not Turn On

    Main PC Board is If the balance fails to turn on defective. and On/Zero Off switch is OK, the Main PC Board is defective and should be replaced. ->Main Printed Circuit Board Removal & Replacement 3.1.3 Ohaus Corporation www.ohaus.com Discovery Balance Service Manual...

  • Page 17: Balance Does Not Respond To Front Panel Controls

    The Display PC Board is replaced partial characters are defective. as a whole assembly. Check displayed. procedures in Table 2-1 first and verify that other problems do not exist. ->Display PCB Removal & Replacement 3.1.2. Discovery Balance Service Manual Ohaus Corporation www.ohaus.com...

  • Page 18: Balance Cannot Calibrate Using External Weights

    (Appendix B) and perform a Span Calibration. If this fails, check the InCal Weight Assembly and the Load Cell Assembly (Section 3.1.5 – 3.2.7). Ensure that all parts are clean and properly aligned. Ohaus Corporation www.ohaus.com Discovery Balance Service Manual...

  • Page 19: Balance Cannot Calibrate Internally

    Main PC Board may be are operational. If not, the Main defective. PC board may be defective. ->Main PCB Removal & Replacement 3.1.3. Replace Load Cell PCB. Load Cell PCB is (See p. 3-27.) defective Discovery Balance Service Manual Ohaus Corporation www.ohaus.com...

  • Page 20: Error Codes

    (during tare, zero, printing, Wait until completion. calibration, etc.) - - - - - - - - - - - Unstable weight reading If balance is level, in appropriate environment, repair Load Cell. Ohaus Corporation www.ohaus.com Discovery Balance Service Manual...

  • Page 21: Chapter 3 Repair Procedures

    CHAPTER 3 REPAIR PROCEDURES REPAIR PROCEDURES This section of the manual contains detailed disassembly procedures of the Discovery Balance. Section 5 of this manual contains exploded views and associated parts lists for all models. Refer to Section 5 drawings before disassembling the balance. Components inside of the balance are delicate.
  • Page 22 1. Remove the two screws shown and then the third one on the bottom. Figure 3-2. Removing back cover. 2. Remove the back cover. Back Screw Figure 3-3. Balance with Back Cover removed. Ohaus Corporation www.ohaus.com Discovery Balance Service Manual...
  • Page 23 7. The Draft Shield Assembly should slide back approximately one-quarter inch. If not, turn the screw one more turn 8. Slide the Draft Shield Assembly toward the back and lift to remove it. Discovery Balance Service Manual Ohaus Corporation www.ohaus.com...
  • Page 24 CHAPTER 3 REPAIR PROCEDURES 3.1.1 Housing Disassembly/Opening the Balance Figure 3-5. Discovery Balance with cover removed, and also cover of main Printed Circuit Board removed. NOTE: When replacing cover, place keyway holes over cone-shaped brass screw heads. Keyway hole on Balance cover Figure 3-6.

  • Page 25: Display Assembly Parts List

    Table 3-1. Display Assembly Parts List Drawing Item Description In Use Cover Function Label Display Housing Upper Printed Circuit Board (PCB) Display Display Cable Display Housing Bottom Figure 3-7. Scale drawing of Discovery Balance Display Parts. Discovery Balance Service Manual Ohaus Corporation www.ohaus.com...

  • Page 26: Removing Screws To Separate Display Housing From Bottom Of Balance

    9. Install Display assembly to balance: tip balance up and insert 2 screws on the bottom. 10. Replace balance cover, performing Housing Disassembly in reverse order. 11. Check balance performance and perform Span Calibration: See Appendix A.2. Ohaus Corporation www.ohaus.com Discovery Balance Service Manual...

  • Page 27: Main Printed Circuit Board (Pcb) Removal & Replacement

    Main PCB Cover Screws RS232 Screws Figure 3-9. Display Balance Load Cell Cover 2. Remove 2 screws from the Main PCB cover and remove the cover. 3. Remove the 2 screws that secure the RS232 connector. Discovery Balance Service Manual Ohaus Corporation www.ohaus.com...

  • Page 28: Discovery Balance Printed Circuit Board (Pcb)

    PCB Screw Cable Connections Cable Connection PCB Screws Figure 3-10. Discovery Balance Printed Circuit Board (PCB). CAUTION WHEN HANDLING THE PRINTED CIRCUIT BOARD, HANDLE BY EDGES ONLY! DO NOT TOUCH FOIL SIDE OF BOARD. STATIC DISCHARGE MAY DAMAGE SOME COMPONENTS. ALWAYS USE AN ANTI-STATIC KIT! 4.
  • Page 29 13. Use the Discovery Service Tool Software to electronically install the new main PCB. (See Appendix C.3.) 14. Perform two calibrations: first Service Calibration (see Appendix B), then Span Calibration. (See Appendix A.2.) 15. Check functioning of the balance. Discovery Balance Service Manual Ohaus Corporation www.ohaus.com...
  • Page 30 If the Weight Mechanism appears to be unstable, the first remedy should be to perform an InCal Weight Mechanism test. This test is done with the Discovery Balance Software Service Tool (see Appendix C, especially C.5 and C.6), installed on a personal computer which is connected to the balance’s RS232 port using a standard serial extension cable.

  • Page 31: The Incal Weight Cover Sits Beneath The Display Cable Shield Plate

    5. Remove both Weights and Weight Holders, and set them aside. 6. Carefully remove any dust or debris from the Weights, Weight Holders, and their environment, using alcohol on a clean cloth. Discovery Balance Service Manual 3-11 Ohaus Corporation www.ohaus.com...

  • Page 32: Incal Weight Hardware Disassembly

    11. Upon satisfactory completion of the InCal Weight Mechanism Test, be sure all hardware is perfectly clean, then reinstall the Weight Holders and Weights and re- assemble the InCal Weight Assembly, following this section in reverse order. Ohaus Corporation www.ohaus.com 3-12 Discovery Balance Service Manual...

  • Page 33: Removing And Replacing Calibration Motor Assembly

    Assembly to Balance chassis. Figure 3-18. Calibration Motor Assembly, closeup. Note screws on right securing it to balance chassis. 2. Remove the screws on the Calibration Motor Assembly and gently lift it out. Discovery Balance Service Manual 3-13 Ohaus Corporation www.ohaus.com...

  • Page 34: Calibration Motor Assembly

    Figure 3-19. Calibration Motor Assembly close-up, showing cam in rest position 3. Install new the Calibration Motor Assembly. Re-insert the 2 screws previously removed. 4. Replace Load Cell Cover following Section 3.2.1 in reverse order. Ohaus Corporation www.ohaus.com 3-14 Discovery Balance Service Manual...

  • Page 35: Load Cell Cover Removal And Disassembly

    2. Remove the 2 screws from the Display Cable Shield Plate and lift it aside. Display Cable Shield Plate screws Figure 3-21. Removing Display Cable Shield Plate. 3. Carefully move the Display Cable to the side. It does not need to be disconnected at this time. Discovery Balance Service Manual 3-15 Ohaus Corporation www.ohaus.com...

  • Page 36: The Incal Weight Cover Sits Beneath The Display Cable Shield Plate

    5. Remove both weights and weight holders, and set them aside. 6. Remove the Main PCB cover as indicated in Section 3.1.3. 7. Disconnect the cables from the PCB. 8. Remove the copper-colored stand-off screws that secure the PCB Mounting Plate. Ohaus Corporation www.ohaus.com 3-16 Discovery Balance Service Manual...

  • Page 37: Lifting Off The Pcb And Its Mounting Plate From The Load Cell

    Figure 3-24. Lifting off the PCB and its Mounting Plate from the Load Cell. 10. Lift off the Load Cell Cover. It has no screws. Figure 3-25. Lifting off Load Cell Cover. Discovery Balance Service Manual 3-17 Ohaus Corporation www.ohaus.com...

  • Page 38: Load Cell With Cover Removed

    12. Tilt the balance onto its back and remove the 3 screws that secure the Load Cell to the Bottom Housing. Screws securing Load Cell to Bottom Housing Figure 3-28. Bottom Housing of Load Cell. Ohaus Corporation www.ohaus.com 3-18 Discovery Balance Service Manual...

  • Page 39: Load Cell Removed

    Figure 3-29. Load Cell chassis. Note position of keyway, facing towards front of balance. 14. Disconnect the cable from the Load Cell by pulling it downward. Figure 3-30. Load Cell removed. Discovery Balance Service Manual 3-19 Ohaus Corporation www.ohaus.com...

  • Page 40: Load Cell Disassembly

    Load Cell top cover. Figure 3-33. Removing screws Figure 3-34. Load Cell with bottom from Load Cell bottom cover. cover removed. NOTE: When covers are removed touch only the frame of the Load Cell. Ohaus Corporation www.ohaus.com 3-20 Discovery Balance Service Manual...

  • Page 41: Screws On Bottom Flexure Arm Assembly

    4. Loosen the 2 screws that connect the top Flexure Arm assembly to the frame, NO MORE than half a turn. This is preparation for mounting the fixture to protect the Flexure Arms. Discovery Balance Service Manual 3-21 Ohaus Corporation www.ohaus.com...

  • Page 42: Service Toolset, Part No. 80030340

    6. With the Load Cell resting on its back frame, slide the Brass Fixture from the Service Toolset under the hanger. After inserting the Brass Fixture part way, gently lift the Brass Fixture, allowing the Brass Fixture to be positioned in place. Ohaus Corporation www.ohaus.com 3-22 Discovery Balance Service Manual...

  • Page 43: Thumb Screws And Hanger On Top Of Load Cell

    Figure 3-41. Screws securing Load Flexure to Hanger on top of Load Cell. 8. Carefully remove the two screws shown, together with 2 washers each: one steel (closest to screw head) and one aluminum. Discovery Balance Service Manual 3-23 Ohaus Corporation www.ohaus.com...

  • Page 44: Load Cell With Load Flexure, 2 Screws And 4 Washers Removed

    11. Carefully examine each Flexure to see if it is bent. If uncertain, place the Flexure on a clean flat surface and check that both sides rest evenly on the surface. If a Flexure is bent even slightly, it must be replaced. Ohaus Corporation www.ohaus.com 3-24 Discovery Balance Service Manual...
  • Page 45 Carefully observe this arc, and be sure to replicate it when re- soldering the wires! Solder points Figure 3-45. Solder points on either side of set screw connecting fine wire to Load Cell PCB. Discovery Balance Service Manual 3-25 Ohaus Corporation www.ohaus.com...

  • Page 46: Lifting Ratio Beam To Insert Brass Rod

    16. On the front of the Load Cell, screw in the Threaded Rod until it touches the Ratio Beam. Threaded Rod Figure 3-48. Screwing in Threaded Rod on front of Load Cell. Ohaus Corporation www.ohaus.com 3-26 Discovery Balance Service Manual...

  • Page 47: Removing Screws From Pcb. (Note Stepped Washer Under Rear Screw)

    Solder points for top Temperature Sensor Solder points for bottom Temperature Sensor Bottom Temperature Sensor Figure 3-51. Solder points on top of Load Cell PCB. Figure 3-52. Solder points on bottom of Load Cell PCB. Discovery Balance Service Manual 3-27 Ohaus Corporation www.ohaus.com...

  • Page 48: Up/Down Stop Plate

    20. Remove the two screws that secure the Magnet Cover, and carefully remove the Magnet Cover by lifting it straight up. Figure 3-55. Removing screws that secure Figure 3-56. Lifting off the Magnet Cover. the Magnet Cover. Ohaus Corporation www.ohaus.com 3-28 Discovery Balance Service Manual...

  • Page 49: Removing Thumb Screws That Hold Hanger In Place

    22. Release Ratio Beam yoke by removing screws on each side. Screw holding Screw holding yoke to frame yoke to frame Figure 3-59. Screws on each side of yoke holding Ratio Beam must be removed. Discovery Balance Service Manual 3-29 Ohaus Corporation www.ohaus.com...

  • Page 50: Load Cell Cleaning

    DO NOT use a cleaning solution. For best viewing, use a fluorescent light with magnifier lens. Check to see if Flexures are bent or broken. Place the Flexure on a clean flat surface and check that both sides rest evenly on the surface. Ohaus Corporation www.ohaus.com 3-30 Discovery Balance Service Manual...

  • Page 51: Load Cell Assembly

    3. Ensure that the hole in the Ratio Beam is centered over the Temperature Sensor Tube, and that the gap between the Coil and the Magnet is even. Move the Ratio Beam assembly only by the yoke, until it is perfectly centered. Discovery Balance Service Manual 3-31 Ohaus Corporation www.ohaus.com...

  • Page 52: Yoke Aligned With Frame Side-To-Side, And Flush With Frame On Front

    5.3. Insert Brass Brackets on both sides. (See Figure 3-66, next page.) 5.4. Press Brackets from each side, and Brass Fixture from below, to ensure that Brackets are snug against yoke, so that if Brackets are pulled there is resistance. Ohaus Corporation www.ohaus.com 3-32 Discovery Balance Service Manual...
  • Page 53 5.15. Remove Thumb screws and detach Brass Fixture and Brass Brackets. 5.16. Remove Centering Pin. 5.17. Loosen Threaded Rod. 5.18. Check centering. 5.19. If necessary, loosen screws that attach yoke to frame and adjust slightly to center. Discovery Balance Service Manual 3-33 Ohaus Corporation www.ohaus.com...

  • Page 54: Hanger Installed, With Brass Fixture And Brass Brackets

    The Hanger’s left and right gap areas should be even when it is installed correctly. Right gap area Left gap area Right side Bracket Left side Bracket Brass Fixture Hanger Figure 3-67. Hanger installed, with Brass Fixture and Brass Brackets. Ohaus Corporation www.ohaus.com 3-34 Discovery Balance Service Manual...

  • Page 55: Magnet Cover Has Oblong Hole That Clears Ratio Beam's Stop Tab

    NOTE: The Temperature Conductor conducts heat from the Magnet to a small PCB on the Ratio Beam, under the Load Cell’s main PCB. The small PCB communicates the heat reading to the balance’s calibration system, which adjusts the balance to compensate for temperature variations. Discovery Balance Service Manual 3-35 Ohaus Corporation www.ohaus.com...

  • Page 56: Up/Down Stop Plate Which Rests On Magnet Cover

    2 screws shown in Figure 3-73. Insert Step Bushing before screw on back end. Place Step Bushing before inserting screw on back of PCB. Figure 3-74. Load Cell PCB is secured with 2 screws. A Step Bushing goes in before the screw in the back. Ohaus Corporation www.ohaus.com 3-36 Discovery Balance Service Manual...
  • Page 57 Figure 3-71, to ensure proper functioning of the balance. 17.4. Solder the wires into place. Solder points Figure 3-75. Fine wires must have smooth arc shown here for the balance to function properly. Discovery Balance Service Manual 3-37 Ohaus Corporation www.ohaus.com...
  • Page 58 Beam Rod from the Load Cell‘s weight Load Cell Ratio Beam Rod should NOT support Load Cell weight. Threaded Rod Figure 3-76. Load Cell should rest on Threaded Rod (left), and base of frame (right). Ohaus Corporation www.ohaus.com 3-38 Discovery Balance Service Manual...

  • Page 59: Installing The Bottom Flexure Arm

    20. Install the top Flexure Arm, with Flexure screw heads facing outward, by inserting the 3 screws, as shown in Figure 3-78. Figure 3-78. Top Flexure Arm Assembly, with Flexure screw heads facing outward. Figure 3-79. Installing the upper Flexure Arm. Discovery Balance Service Manual 3-39 Ohaus Corporation www.ohaus.com...

  • Page 60: Load Flexure, Aluminum Washers, Steel Washers And Screws

    22. Gently tighten the upper screw, then the lower screw. NOTE: If Load Flexure begins to rotate when tightening screws, STOP IMMEDIATELY, to avoid bending or breaking the Flexure. If Flexure bends, replace it. Ohaus Corporation www.ohaus.com 3-40 Discovery Balance Service Manual...

  • Page 61: Hanger With Thumb Screws Removed

    24. Push the Brass Fixture from the grooved side, then pull it out from the square side. Figure 3-83. Pushing Brass Fixture from grooved side. Figure 3-84. Pulling Brass Fixture out from square side. Discovery Balance Service Manual 3-41 Ohaus Corporation www.ohaus.com...

  • Page 62: Note Stops On Sides Of Bottom Load Cell Cover

    Stops on sides of bottom Load Cell cover Screw holes Figure 3-85. Note stops on sides of bottom Load Cell Cover. Figure 3-86. Tightening screws on bottom Load Cell Cover. Ohaus Corporation www.ohaus.com 3-42 Discovery Balance Service Manual...

  • Page 63: Top Load Cell Cover Rests Flush Against Bottom Cover

    Make sure the cover does not touch any screws. Figure 3-87. Top Load Cell Cover rests flush against bottom cover. 27. Tighten the screws, as shown in Figure 3-88. Figure 3-88. Tightening screws on top Load Cell Cover. Discovery Balance Service Manual 3-43 Ohaus Corporation www.ohaus.com...
  • Page 64 CHAPTER 3 REPAIR PROCEDURES 3.2.4 Load Cell Assembly 28. Gently push on the Hanger to make sure it moves freely and smoothly. Figure 3-89. Hanger should move smoothly when touched. Ohaus Corporation www.ohaus.com 3-44 Discovery Balance Service Manual...

  • Page 65: Installing Load Cell

    Cantilever Arm should be equal. (See Figure 3-92.) Note: The Cantilever Arm is delicate and should be handled carefully. Do not use the Cantilever Arm to adjust the Load Cell position. Discovery Balance Service Manual 3-45 Ohaus Corporation www.ohaus.com...

  • Page 66: Replacing Load Cell Cover

    7. Note the notches for cables: top-left for Load Cell cable, and bottom-right for Calibration Motor Assembly cable. Figure 3-94. Load Cell with Cover in proper position, cables resting in notches (top-left and bottom-right). Ohaus Corporation www.ohaus.com 3-46 Discovery Balance Service Manual...

  • Page 67: Placing Pcb Mounting Plate On Load Cell

    Tighten with a wrench. Figure 3-96. Stand-off screws secure PCB Mounting Plate. 10. Connect the cables to the PCB. Pass the small cable through the rectangular slot on the right of the PCB Mounting Plate. Discovery Balance Service Manual 3-47 Ohaus Corporation www.ohaus.com...

  • Page 68: Installing Weights And Weight Holders

    11.3. Place the InCal Weight Cover over the Weights, aligning the screw holes left and right. (The screws will be installed in the Display Cable Shield Plate, which rests on top of the InCal Weight Cover.) Figure 3-98. Proper position of InCal Weight Cover. Ohaus Corporation www.ohaus.com 3-48 Discovery Balance Service Manual...

  • Page 69: Correct Position Of Display Cable Under Display Cable Shield Plate

    Pan Socket is centered in hole in middle of Plate. Display Cable running under Display Cable Shield Plate Figure 3-100. Correct position of Display Cable under Display Cable Shield Plate. Discovery Balance Service Manual 3-49 Ohaus Corporation www.ohaus.com...

  • Page 70: Securing Pcb Cover

    Replace Load Cell. 18. Perform a Span Calibration, in accordance with the instructions in Appendix A.2. 19. Check the performance of the balance using the tests in Section 4-2. Ohaus Corporation www.ohaus.com 3-50 Discovery Balance Service Manual...

  • Page 71: Chapter 4 Testing

    1. Turn the balance on by pressing ON/ZERO Off, all segments are enabled and displayed briefly, then followed by a software revision number. See Figure 4-1 for full display. Figure 4-1. LCD Full Display for Discovery Balance. 2. Tare the balance. The display should indicate a zero weight. Load Cell Performance Tests 4.2.1 Off-Center Load Test...

  • Page 72: Adjusting Off Center Load

    Figure 4-2. Holes in back cover must be popped out to insert Allen Keys. The recommended position for the OCL adjustment is shown in Figure 4-3. Figure 4-3. Proper position for adjusting Off-Center Load. Ohaus Corporation www.ohaus.com Discovery Balance Service Manual...
  • Page 73 Figure 4-4 shows the front part of the scale with the Allen Keys sticking out in the back. The arrows show the key rotation directions required to bring the weight within tolerance specification. (See Table 1-2 – Discovery Balance Model Specifications.) Figure 4-4. Allen key rotation directions needed for back-edge-heavy, back-edge-light, right-edge- heavy and right-edge-light conditions.

  • Page 74: Repeatability Test

    3. Remove the mass. Reading should return to 0g ± 1 count. 4. Repeat the test for ten readings. If the standard deviation of the readings is within the specifications in Table 1-2 (Discovery Balance Model Specifications, page 1-3), the balance passes the Repeatability Test.

  • Page 75: Linearity Test

    10. The difference in the weights of the test mass should be within the tolerance in Table 1-2. If not, perform an internal calibration (see Appendix A.1) and repeat the test. 11. If the balance remains out of tolerance, the Load Cell may need to be repaired. Discovery Balance Service Manual Ohaus Corporation www.ohaus.com...

  • Page 76: Rs232 Interface Test

    CHAPTER 4 TESTING RS232 Interface Test The Discovery Balance Interface can be tested using an external printer or computer connected to the Balance. The RS232 menu provides communication parameters which can be set to accommodate external printers or computers. It contains three submenus: Baud rate, Parity and Handshake.

  • Page 77: Connecting The Rs232 Interface

    CHAPTER 4 TESTING 4.4.1 Connecting the RS232 Interface Figure 4-5. Com 1 Connector, as it appears on balance’s back cover. TABLE 4-2. COM1 INTERFACE PIN CONNECTIONS: Not used Ground Not used Discovery Balance Service Manual Ohaus Corporation www.ohaus.com...

  • Page 78: Rs232 Commands

    Scroll to the next enabled mode. Print current weighing unit. Scroll to the next enabled unit. Turns balance OFF. Turns balance on. Print Serial Number Print Version: name, software revision and LFT ON (if LFT is set ON). Ohaus Corporation www.ohaus.com Discovery Balance Service Manual...

  • Page 79: Print Test

    Measure the Voltage between Pin A and Pin B of the Adapter (see Figure 4-6) to assure the proper voltage. Note: Measure the Voltage between Pin A and Pin B Pin A Pin B Figure 4-6. AC Adapter Cord. Discovery Balance Service Manual Ohaus Corporation www.ohaus.com...

  • Page 80: Chapter 5 Parts Lists & Diagrams

    Glass Bottom Draft Shield Platform Grommet Door Track Set Draft Shield Glass Front Draft Shield Door Handle Draft Shield Set Top Door Draft Shield Not Shown Sealing Tape Figure 5-1. Discovery Balance Housing. Discovery Balance Service Manual Ohaus Corporation www.ohaus.com...

  • Page 81: Discovery Display Assembly

    TABLE 5-2. PARTS LIST FOR DISCOVERY DISPLAY ASSEMBLY Drawing Item Description In Use Cover Function Label Display Housing Top Display Printed Circuit Board (PCB) Display Cable Display Housing Bottom Figure 5-2. Discovery Balance Display Assembly. Ohaus Corporation www.ohaus.com Discovery Balance Service Manual...

  • Page 82: Discovery Internal Parts Outside Load Cell

    Calibration Motor Assembly Calibration Weight Arm Calibration Weight Holder InCal Weights Cover Weight Cover Bushing Display Cable Shield Plate Calibration Weight Bubble Level CR2032 Lithium Battery Figure 5-3. Internal Parts Outside Load Cell. Discovery Balance Service Manual Ohaus Corporation www.ohaus.com...

  • Page 83: Discovery Load Cell Parts

    Ratio Beam Flexure, 2 washers & screw Magnet Cover Temperature Conductor Up/Down Stop Plate Not Shown Load cell Hardware Kit Figure 5.4 Discovery Balance Load Cell Parts. NOTE: For Part Numbers for specific Discovery Models, see specific parts lists. Ohaus Corporation www.ohaus.com Discovery Balance Service Manual...

  • Page 84: Appendix A Standard Calibration

    Figure A-1. Calibration Menu flow: Press No until the desired option appears, then Yes. Before beginning calibration, have masses available. Masses required for calibration are listed in Table A-1, at the end of this section. Discovery Balance Service Manual Ohaus Corporation www.ohaus.com...

  • Page 85: Automatic Internal Calibration (Advanced Auto Cal

    Press No to toggle the display from AUTOCAL SET ON to AUTOCAL SET OFF, then press Yes. Press Exit to exit the Calibrate Menu. Repeat this process to re-activate AutoCal. Automatic internal calibration is included in all Discovery models. Ohaus Corporation www.ohaus.com Discovery Balance Service Manual...

  • Page 86: Span Calibration

    This may mean the balance is unstable – level the balance and try again. If still unsuccessful, check for ABORT problems as explained in Chapter 3 of this manual. When calibration is finished, the balance returns to the weighing mode. Discovery Balance Service Manual Ohaus Corporation www.ohaus.com...

  • Page 87: Calibration Test (Cal Test

    After a short period, the display indicates the difference in weight from the last calibration, and then will display the calibration weight on the Pan. After the test, remove the calibration weight from the Pan. To leave the menu, press Exit. Ohaus Corporation www.ohaus.com Discovery Balance Service Manual...

  • Page 88: Calibration Adjustment (Cal Adj

    Press Back to decrease the d value until the setting matches the desired d value. Press Yes to accept and store the setting. TABLE A-1. CALIBRATION MASSES FOR DISCOVERY BALANCE MODELS Model Span Calibration Points (1) Weight Class...

  • Page 89: Appendix B Service Calibration

    RAMP powers up, the display advances through several screens. SERVICE is displayed with RAMP flashing. Press Yes to select Ramp. (See next page.) Press No to advance to Span Calibration. (See page B-3.) Discovery Balance Service Manual Ohaus Corporation www.ohaus.com...

  • Page 90: Ramp

    The balance advances to the Span calibration menu. Press Yes to perform Span Calibration. Press No to SPAN advance to Int Cal Calibration, and No again to End Srv. If you press Yes at this point, the balance goes off. Ohaus Corporation www.ohaus.com Discovery Balance Service Manual...

  • Page 91: Service Span Calibration

    Service Ramp. If Span calibration fails, refer to Chapter 3, and ABOrt check the InCal Weight Mechanism, and the Load Cell assembly. Clean and/or repair as necessary. Discovery Balance Service Manual Ohaus Corporation www.ohaus.com...

  • Page 92: Service Internal Calibration (Incal

    First try to re-stabilize the balance and try again. If calibration still fails, refer to Chapter 3, ABORT check the InCal Weight Mechanism, and the Load Cell assembly. Clean and/or repair as necessary. Ohaus Corporation www.ohaus.com Discovery Balance Service Manual...

  • Page 93: Appendix C Software Service Tool Instructions

    Click on the tab for the function you wish to perform. If the default settings for communication have been changed, click on settings and change the settings in the software to match. Figure C-1. Com Port Configuration menu. Discovery Balance Service Manual Ohaus Corporation www.ohaus.com...
  • Page 94 1.2. Model Number from the label on the back of the balance. 1.3. IDNR Number, just above the label on the back of the balance. 2. Contact Ohaus Corporation in Pine Brook NJ, and request the data file to download. Provide the information recorded above.

  • Page 95: Replace Load Cell

    9. Click the Start button. 10. The software will indicate the download progress. When complete, disconnect the power from the back of the balance, then re-connect. 11. Perform Service Calibrations (see Appendix B). Test the balance. Discovery Balance Service Manual Ohaus Corporation www.ohaus.com...

  • Page 96: Install New Main Printed Circuit Board

    6. Click the Start button 7. The software will indicate the download progress. When complete, disconnect the power from the back of the balance, then re-connect. 8. Perform Service Calibrations (see Appendix B). Test the balance. Discovery Balance Service Manual Ohaus Corporation www.ohaus.com...

  • Page 97: Update Software In The Balance

    6. When prompted, disconnect the power from the back of the balance, then re-connect. 7. The software will indicate the download process. When complete, disconnect the power from the back of the balance, then re-connect. 8. Perform Service Calibrations (see Appendix B). Test the balance. Discovery Balance Service Manual Ohaus Corporation www.ohaus.com...

  • Page 98: Diagnostics

    A fluctuating display value indicates the weight is not stable. This could be because the weight is not fully lowered and/or because it is touching something. To correct this symptom, follow the procedures in Section 3.1.5 InCal Weight Hardware Disassembly & Testing. Discovery Balance Service Manual Ohaus Corporation www.ohaus.com...
  • Page 99 Официальный представитель: Компания "Мир Весов" 115409, Москва, ул. Москворечье 47, корп. 2 Тел./ факс: (495) 921-44-57 http://www.mirvesov.ru E-mail: mv@mirvesov.ru *80104135* P/N 80104135 SERVICE MANUAL: DISCOVERY BALANCE...

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