OHAUS Defender D150BL, Service Manual

Page 1: ...SERVICE MANUAL Defender Bases Dry use B Series Wet use V Series Ohaus Corporation 7 Campus Drive Suite 310 Parsippany NJ 07054 973 377 9000 ...

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Page 3: ... 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 TM Registered trademark of Ohaus Corporation ...

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Page 5: ...Replacing the Load Cell 3 1 3 3 Overload Stop Adjustments 3 2 CHAPTER 4 TESTING 4 1 Testing 4 1 4 2 Load Cell Resistance Checks 4 1 4 3 Calibration with an External Indicator 4 1 4 4 Consistency Check 4 2 4 5 Performance Tests 4 2 4 5 1 Off Center Load Shift Test 4 3 4 5 2 Adjusting Off Center Load 4 4 4 5 3 Full Load Test 4 5 CHAPTER 5 DRAWINGS AND PARTS LISTS 5 1 Defender B V Bases Housing Inter...

Page 6: ...d output 1 5 3 1 Four Mounting Bolts that secure the Top Frame to the Load Cell 3 1 3 2 Four Mounting Bolts that secure the Bottom Frame to the Load Cell 3 2 3 2 Overload Stops 3 2 4 1 Positions A B C and D are Centered 4 3 4 2 Off Center Load adjustment points 4 4 5 1 Defender B V Bases Housing Internal Parts 5 2 Defender B V Series Service Manual ii Ohaus Corporation www ohaus com ...

Page 7: ... preventive maintenance procedures and disassembly repair and replacement procedures Chapter 4 Testing Contains guides for operational and performance tests and adjustments Chapter 5 Drawings and Parts Lists Contains exploded views of the Defender Bases and parts identifying all serviceable components with parts lists Before servicing the Base you should be familiar with the Instruction Manual whi...

Page 8: ...of Load Cells with connecting cable and hardware Each base contains the following basic replaceable assemblies Platform Load Cell with Connecting Cable and Down Stop and mounting hardware There is an exploded view drawing of the Base and associated parts list in Chapter 5 This service manual contains sufficient information to isolate the problem replace the component test and restore the Base to f...

Page 9: ...minum single point C3 MODEL V Series D30VR D60VR D60VL D150VL D150VX D300VX Construction 304 stainless steel pan and frame non slip rubber leveling feet Load Cell Protection Accuracy Class IP67 stainless steel single point C3 Capacity 30 kg 60 kg 60 kg 150 kg 150 kg 300 kg Maximum Resolution 6000d 6000d 6000d 7500d 7500d 6000d Safe Overload Capacity 125 of capacity Load Cell Rated Output 2 mV V 10...

Page 10: ... 1 1 Typical Strain Gauge Load Cell Internal PCB The strain gauges are wired into a Wheatstone Bridge Circuit See Figure 1 2 Strain Gauge Strain Gauge Force Strain Gauge Strain Gauge Printed Circuit Board PCB completing Wheatstone Bridge circuit Wheatstone Bridge Circuit Figure 1 2 Downward force on the Platform bends the beam causing two gauges to stretch and two to compress in opposition changin...

Page 11: ...ower source in the Indicator and sends back a low voltage milli volt mV relative to the force applied The Load Cell signal is read by the Indicator which converts it to a numeric value and shows it visually This output value increases as weight is loaded to the Load Cell For example a 500kg Load Cell with 2mV V output and 5V excitation would have a change of 0 02mV per kg change in the load that i...

Page 12: ...CHAPTER 1 INTRODUCTION Ohaus Corporation www ohaus com 1 6 Defender B V Series Service Manual ...

Page 13: ...d restrict movement causing improper operation of the Base If the Overload Stops are improperly set adjust them See Section 3 3 Check the metal surfaces of the Platform All surfaces should be parallel If the platform is deformed it should be replaced Check the cables leading to the Load Cell for cuts abrasions or other signs of excessive wear and tear Check for a bent or twisted Load Cell Place th...

Page 14: ...CHAPTER 2 DIAGNOSTIC GUIDE Ohaus Corporation www ohaus com 2 2 Defender B V Series Service Manual ...

Page 15: ...he base 2 Remove the Platform to inspect and clean the area beneath the Platform CAUTION DO NOT USE CHEMICAL CLEANERS OR SOLVENTS OF ANY TYPE SOME CLEANERS ARE ABRASIVE AND MAY AFFECT THE BASE S FINISH 3 Check the Load Cell cable for broken or damaged insulation 4 Make a visual inspection as detailed in Chapter 2 3 2 Replacing the Load Cell A Load Cell that is even slightly bent or corroded should...

Page 16: ...s The Overload Stop gaps must be checked and reset if the Load Cell is replaced 1 Remove the Platform and loosen the Jam Nuts first on the four Overload Stops on the top side of the Frame then on the bottom See Figures 3 3 3 4 and 3 5 2 Use the appropriate size feeler gauge in the Gap see Table 3 1 and turn the set screws until a slight drag is felt on the feeler 3 Tighten the Jam Nut and re check...

Page 17: ...ty Overload Stop Corner Overload Stop Center D30BR 30kg 0 6 35 D60BR 60kg 0 8 0 5 D60BL 60kg 2 8 0 7 D150BL 150kg 2 2 0 4 D150BX 150kg 2 5 0 4 D300BX 300kg 4 0 5 D30VR 30kg 0 6 35 D60VR 60kg 0 8 0 5 D60VL 60kg 2 8 0 7 D150VL 150kg 2 2 0 4 D150VX 150kg 2 5 0 4 D300VX 300kg 4 0 5 Defender B V Series Service Manual 3 3 Ohaus Corporation www ohaus com ...

Page 18: ...CHAPTER 3 MAINTENANCE AND REPAIR PROCEDURES Ohaus Corporation www ohaus com 3 4 Defender B V Series Service Manual ...

Page 19: ...o the four resistance elements which make up the Wheatstone Bridge there are commonly one or two resistors in the excitation lines The resistance across the excitation wires is usually the highest resistance measured across any two wires If the resistance readings are in the range specified skip to the next section If they are incorrect for example outside the expected range open circuit or short ...

Page 20: ...and record the signal voltage at the loads shown in Table 4 2 4 Compare the measured output readings with the theoretical values from the Load Cell data See Table 4 2 TABLE 4 2 LOAD CELL OUTPUT READINGS in mV with 5V Excitation Model Capacity Zero Load 50 Load 100 Load D30BR 30kg 1 3 1 0 Zero 2 8 Zero 5 6 D60BR 60kg 1 1 1 0 Zero 2 55 Zero 5 1 D60BL 60kg 1 1 1 0 Zero 2 55 Zero 5 1 D150BL 150kg 1 3 ...

Page 21: ...ll sections of the Base weigh within specified tolerance If the Base does not pass the Off Center Load Test verify that the Overload Stops are properly set See Section 3 1 If the Off Center Load Test cannot be passed the Load Cell must be adjusted or replaced Prior to starting this test the Base must be connected to a properly functioning Indicator with capacity and readability values set accordin...

Page 22: ...weight to point D and record the reading 7 If the reading at point A is negative file at points 1 and 4 AT AN ANGLE 8 If the reading at point B is negative file at points 1 and 2 STRAIGHT ACROSS 9 If the reading at point C is negative file at points 2 and 3 AT AN ANGLE 10 If the reading at point D is negative file at points 3 and 4 STRAIGHT ACROSS Note It is not recommended that you try to adjust ...

Page 23: ...test the Base s full capacity according to the Specification Tables 1 1 through 1 6 The Base must meet all specifications as listed 2 If the Base fails the Full Load Test check and set the Overload Stops See Section 3 3 Defender B V Series Service Manual 4 5 Ohaus Corporation www ohaus com ...

Page 24: ...CHAPTER 4 TESTING Ohaus Corporation www ohaus com 4 6 Defender B V Series Service Manual ...

Page 25: ...ld NOTE In all cases where a part is replaced the base must be thoroughly checked after the replacement is made The base MUST meet the parameters of all applicable specifications in this manual If further technical information is needed please contact your local Ohaus office or Ohaus Corporation www ohaus com 7 Campus Drive Suite 310 Parsippany NJ 07054 USA Tel 973 377 9000 Fax 973 593 0359 In the...

Page 26: ...CHAPTER 5 PARTS LISTS DIAGRAMS 5 1 DEFENDER B V SERIES BASES PARTS Figure 5 1 Defender B V Series Bases Parts Ohaus Corporation www ohaus com 5 2 Defender B V Series Service Manual ...

Page 27: ... 2 Hardware Kit 3 Rubber Load Pads set of 6 6 Load Cell 8 Level Kit 9 Foot 1 When replacement parts are needed refer to the spare part list for the model you are servicing Parts lists are available from your local Ohaus office To locate your local office visit Ohaus com Defender B V Series Service Manual 5 3 Ohaus Corporation www ohaus com ...

Page 28: ...CHAPTER 5 PARTS LISTS DIAGRAMS Ohaus Corporation www ohaus com 5 4 Defender B V Series Service Manual ...

Page 29: ...d Over the full rated capacity of the load cell the mV output will change The amount by which it changes depends upon the resistance change in the cell and on the excitation voltage applied Since the load cell manufacturer does not know what excitation voltage will be applied to the cell rather than quote the V output over full range they will quote the milli Volt output per volt of excitation or ...

Page 30: ...APPENDIX A GLOSSARY Ohaus Corporation www ohaus com A 2 Defender B V Series Service Manual ...

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Page 32: ... 80252594 P N 80252594 A SERVICE MANUAL DEFENDER B V SERIES BASES ...