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CHAPTER 2  DIAGNOSTIC GUIDE 

Ohaus Corporation  www.ohaus.com 

2-4 

Ranger

 (Count) 3000 Series Service Manual 

2.2.3  Testing the Printed Circuit Board (PCB) 

The PCB 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. 

PCB Voltage Measurements 

Note:  

Prior to the voltage measurements, the battery should be fully charged and tested. 

1.  Disconnect power from the scale, and remove the Top housing. (See Section 3.3.1.) 

 

   

CAUTION: 

Disconnect the power from the scale before opening the housing. 

         

2.  Connect the AC Adapter to the scale and turn the scale on. 

3.  Using a DVM, measure the excitation voltage (EXE+ and EXE

 in Figure 2-1.)   

The reading should be 3.1 volts dc. This is the excitation voltage for the Load Cell  
and is regulated. If the voltage is lower, replace the PCB.  (See Section 3.4.)   
Then perform Operational Tests. (See Chapter 4.) 

4.  Measure incoming power from the transformer connector shown in Figure 2-1. The 

voltage should read 0 volts with power off and above 12 Volts dc with power on. 

5.  Perform simulator testing. 

Simulator Testing 

To perform these tests, the use of a Simulator is required. The 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. The Load Cell used in the scale is rated 
at 2mV/V output with a 3.1 Volt excitation voltage applied. 

 

 

 

 

 

 

 

 

 

 

 

Summary of Contents for Ranger 3000 Series

Page 1: ...SERVICE MANUAL RANGER 3000 RANGER Count 3000 Scales Ohaus Corporation 7 Campus Drive Suite 310 Parsippany NJ 07054 973 377 9000...

Page 2: ...t 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 sub...

Page 3: ...egal For Trade 1 9 1 7 1 Settings 1 3 1 7 2 Verification 1 4 1 7 3 Sealing 1 5 CHAPTER 2 TROUBLESHOOTING 2 1 Troubleshooting 2 1 2 2 Diagnostic Guide 2 1 2 2 1 Diagnosis 2 1 2 2 2 Checking Load Cells...

Page 4: ...he Service Menu B 1 B 3 Capacity Menu B 2 B 4 Graduation Menu B 2 B 5 Service Span Calibration B 2 B 6 Service Linearity Calibration B 3 B 7 Ramp Menu B 4 B 8 Expand Menu B 4 B 9 End Menu B 4 LIST OF...

Page 5: ...r 3000 Front Display with controls 1 6 1 3 LFT Lock Switch and Seal 1 9 2 1 Main Printed Curcuit Board 2 3 3 1 Screws securing Top Housing 3 2 3 2 Top and Bottom Bottom 3 2 3 3 Main Printed Circuit Bo...

Page 6: ...serviceable components Appendix A Standard Calibration Explains procedures for Standard Calibration performed prior to using a scale and after service Appendix B Service Calibration Describes the Serv...

Page 7: ...esolution 1 30000 1 30000 1 30000 1 30000 1 30000 LFT ON Resolution nMax 1 3000 1 3000 1 3000 1 3000 1 3000 Linearity 2d r0 0001 kg r0 0002 kg r0 0005 kg r0 001 kg r0 002 kg Repeatability 2d r0 0001 k...

Page 8: ...ieces ID ID number input for library record edit recall APW Display Store an APW Secondary Function Long Press 2 Off Turn scale off Units Change the weighing unit Switch between Check Weigh Check Coun...

Page 9: ...to battery operation if there is a power failure or the power cord is removed With AC power the scale is constantly charging so the battery charge indicator will remain lit until fully charged The sc...

Page 10: ...oz lb oz End P r i n t C O M L O C k E n d Menu Items Reset Stable A Print Contnt Layout Data Tr End Reset Baud Parity Stop Handsh Alt Cm End L Cal L Setup L Read L Unit L Print L COM End 1 5 4 Menu...

Page 11: ...gles through active weighing units Short Press in Menu Toggles through available settings Function Mode Back Short Press Selects function setting Long Press Selects active Mode Short Press in Menu ret...

Page 12: ...ing The indicator will automatically turn off when the batteries are fully charged TABLE 1 6 Symbol Charge level 0 to 10 Remaining 11 to 40 Remaining 41 to 70 Remaining 71 to 100 Remaining LED models...

Page 13: ...E n d Menu Items Reset kg g lb oz lb oz End Reset Stable A Print Contnt Layout Data Tr End Reset Baud Parity Stop Handsh Alt Cm End L Cal L Setup L Read L Mode L Unit L Print L COM End Note 1 only for...

Page 14: ...not accessible Unit menu Auto Tare are locked at their current setting s Filter is locked at current setting Stable Range setting is locked at 1d Zero Range setting is locked at 2 Auto Zero Tracking...

Page 15: ...ed with the most common cause first If the first remedy does not fix the problem proceed to the next remedy Before attempting to repair the balance read all chapters of this manual to be familiar with...

Page 16: ...oad output The reading should meet the Load Cell specifications The Load Cell output should be very close to linear over its capacity range NOTE The following steps involve power applied to the scale...

Page 17: ...capacities See Table 2 3 for typical readings Figure 2 1 Top view of main PCB NOTE Table 2 3 indicates typical readings Actual values can vary but should remain linear throughout the range If readings...

Page 18: ...le on 3 Using a DVM measure the excitation voltage EXE and EXE in Figure 2 1 The reading should be 3 1 volts dc This is the excitation voltage for the Load Cell and is regulated If the voltage is lowe...

Page 19: ...value 6 Adjust the Simulator to simulate 0 load 50 load and 100 load for the capacity that the scale is rated for See Table 2 3 for values to use If the resulting readings are unstable the Main PC Boa...

Page 20: ...elow Power On Zero limit Err 8 3 Over Range Error Weight reading exceeds Overload limit Err 8 4 Under Range Error Weight reading below Underload limit Err 8 5 Tare out of range Adjust tare value to be...

Page 21: ...to stabilize 3 1 1 Preventive Maintenance Checklist The scale should be inspected and checked regularly as follows 1 Remove the Pan and Sub Pan to inspect and clean the area beneath the Pan 2 Clean th...

Page 22: ...le over Remove the eight screws holding the Housing in place See Figure 3 1 3 Move the top housing a little bit backward and then raise and remove the top housing 4 Separate Top Housing from Bottom Ho...

Page 23: ...he PCB to the bottom housing 3 If either the Main PCB or the Load Cell is to be replaced note the order of the wire colors and then disconnect the Load Cell Cable from the Main PCB See Figure 3 2 4 Po...

Page 24: ...nd washers that hold the Load Cell assembly frame and load cell to the Bottom Housing Remove the bolts and their washer pairs that hold the Load Cell Frame to the Load Cell Use a high leverage Allen w...

Page 25: ...edure requires test masses equal to the scale s capacity See Table 3 2 There are four Overload Stop Bolts See Figure 3 5 Adjust the Overload Stops per Table 3 2 1 Adjust the Overload Stop Bolt so that...

Page 26: ...SETTINGS Model Max Capacity Overload Stop Gap R3000 RC 3000 Scale Load Cell A B mm C D mm R31P E 1502 RC31P1502 1 5kg 3kg 0 6 0 5 R31P E 3 RC31P3 3kg 5kg 0 8 0 7 R31P E 6 RC31P6 6kg 10kg 1 5 1 1 R31P...

Page 27: ...battery leads 2 Pull the quick connect tabs free of the battery posts and lift out the battery Figure 3 7 Rechargeable battery 3 Position the replacement battery in the compartment on an angle suffici...

Page 28: ...required to test the Ohaus Ranger 3000 Ranger Count 3000 scales must meet the requirements of ASTM Class 4 or OIML F2 Tolerance The mass values are listed in Table 4 1 TABLE 4 1 TEST MASS VALUES Model...

Page 29: ...ch the specification for each model listed in Table 1 1 1 Power on the balance The reading on the display should be 0g 2 Select a mass weighing near the maximum capacity of the balance and place it on...

Page 30: ...lity test set up the instrument as follows Set Up Follow the steps in Appendix A Section A 2 Setup and Calibration Record Settings Zero Tracking Setting ____________ Displayed Units ____________ Mass...

Page 31: ...verage 6 Mean Reading 1 Reading 2 Reading 3 Reading 4 Reading 5 7 Reading 6 Reading 7 Reading 8 Reading 9 Reading 10 10 Mean ________ 6 Calculate the Delta for each reading and record in the work shee...

Page 32: ...and press ON Zero Off 3 Place the test mass on the Scale record the weight and remove 4 Place Load 2 on the Scale and press ON Zero Off 5 Place the test mass on the Scale record the weight and remove...

Page 33: ...1 Place the test weight in the center of the Weighing Pan 2 Tare the balance 3 Move the weight to point A and record the reading 4 Move the weight to point B and record the reading 5 Move the weight...

Page 34: ...le in the field NOTE In all cases where a part is replaced the scale must be thoroughly checked after the replacement is made The scale MUST meet the parameters of all applicable specifications in thi...

Page 35: ...CHAPTER 5 PARTS LISTS DIAGRAMS Ohaus Corporation www ohaus com 5 2 Ranger Count 3000 Series Service Manual 5 1 Ranger 3000 SCALES PARTS Figure 5 1 Ranger 3000 Scales Parts...

Page 36: ...1PE15JP 30037405 LoadCell AMI C3 40kg R31P30 R31PE30JP 7 30037435 Spider Down R31 R21 RC31 RC21 V71 8 30037420 Hardware Kit R31 R21 RC31 RC21 V71 9 30037398 Housing Bottom R31 10 30037421 Feet R31 R21...

Page 37: ...CHAPTER 5 PARTS LISTS DIAGRAMS Ohaus Corporation www ohaus com 5 4 Ranger Count 3000 Series Service Manual 5 2 RANGER COUNT 3000 SCALES PARTS Figure 5 2 Ranger Count 3000 Scales Parts...

Page 38: ...I C3 40kg RC31P30 7 30037435 Spider Down R31 R21 RC31 RC21 V71 8 30037420 Hardware Kit R31 R21 RC31 RC21 V71 9 30037398 Housing Bottom R31 10 30037421 Feet R31 R21 RC31 RC21 V71 11 30037422 Cover Opti...

Page 39: ...alibration process 2 Allow the scale to warm up for approximately five minutes after stabilizing to room temperature 3 To abort calibration press Exit key or turn the scale off anytime during the cali...

Page 40: ...accept SpaN will then be shown Press Yes to begin the span calibration 0 kg will be displayed SpaN 0 3 Press Yes to accept C will be displayed while zero reading is stored Next the display shows the...

Page 41: ...uch the scale or the surface it rests on while calibration is in progress as it will cause the process to fail B 1 Service Menu Structure B 2 Entering the Service Menu Turn the scale off Ranger Count...

Page 42: ...e Service Span Calibration menu Set the graduation of the scale 0 00005 0 02 Grad B 5 Service Span Calibration When SPAN appears press YES to accept the Service Span Calibration menu or No to advance...

Page 43: ...to indicate the calibration unit The example shows the mid calibration point value for a Scale Capacity of 3 kg Place the specified calibration weight on the pan and press Yes C flashes while the mid...

Page 44: ...o the Expand menu item Note Ramp is used to troubleshoot load cell problems 0 represents no signal from the A D 100 reflects the upper signal range of the A D ramMp 0 0 to 100 0 B 8 Expand Menu When e...

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