SERVICE MANUAL MB23 and MB25 Moisture Analyzers
Contents
1. 3 11 3 8 7 Replacing the Thermal Overload 3 12 9 0 9 Replacing TNE F Alena 3 13 3 8 9 Replacing the Temperature 3 14 39 nstaling the Top Aussee ern 3 15 CHAPTER 4 FINAL TESTING Page No ee ee nee 4 1 OBErAlonallest Ans ee ru 4 1 43 Segment Display 4 1 4 4 4 1 Ohaus Corporation www ohaus com MB23 25 Service Manual TABLE OF CONTENTS CHAPTER 4 FINAL TESTING continued Page No Al We ME CIGLORY 4 2 4 4 2 Repeta pliy ern 4 3 44S Linearity a a N 4 4 CHAPTER 5 DRAWINGS AND PARTS LISTS 5 1 23 and MB25 Housing amp Internal 5 2 Appendix A STANDARD CALIBRATION AST 5 46 m 1 A2 Temperature GaliOra nom D in 2 AS 0 205945 A 3 Appendix B SERVICE CALIBRATION amp SOFTWARE SERVICE TOOL Bal estre EEPROM Pilates ee B 2 Replace Load neuere B 3 Update Software in the Analyzer kaiii aa A B 4 BA BIAQNOSIES nee PETERE B 5 Bor2. OO BD COQ MB23 amp MB25 5 2 MB23 and MB25 Service Manual MB23 amp MB25 Housing amp Internal Parts Figure 5 1 Ohaus Corporation www ohaus com CHAPTER 5 PARTS LISTS amp DIAGRAMS 5 1 MB23 amp MB25 HOUSING amp INTERNAL PARTS TABLE 5 1 MB23 amp MB25 HOUSING amp INTERNAL PARTS Top Housing Chamber Reflector o Temperatur Sensor 2 4 ice MB23 8 2 3 5 0 a fweontae O omes SS 39 1 w 4 4 4 4 4 4 4 4 4 4 2 2 2 2 2 7 MB23 and MB25 Service Manual 5 3 Ohaus Corporation www ohaus com CHAPTER 5 PARTS LISTS amp DIAGRAMS Ohaus Corporation www ohaus com 5 4 MB23 and MB25 Service Manual APPENDIX A CALIBRATION APPENDIX A CALIBRATION A 1 WEIGHT CALIBRATION Weight calibration is rarely required Moisture analyzers use relative weight values to determine results so a minor offset from the absolute weight has little effect on accuracy PREPARATION Ensure scale is level stable and undisturbed during calibration Allow scale to warm up for five minutes after stabilizing to room temperature Have 509 calibration mass available Remove any load from the Pan including the sample pan Note To cancel calibration without saving changes press Ly Place weight on pan sum Clear pan N nun
3. 24 9 Figure 1 1 MB23 and MB25 Function Labels N A EE EN LO es TABLE 1 2 FUNCTIONS OF DISPLAY iue a On short press Off long press Start Stop Start Stop short press Set 4 Back short press JP Tare Tare short press Set v Decrease value Enter Accept value short press short or long press sh Temperature Setting shor press Prmuca Pint stor press Time Time Setting short press Result Unit short press There are also several modes of operation which affect how each button operates Please refer to the following section 1 5 2 Overview of the Display Indicators 95 Solid O Moisture Temperature setting or dia NE NE IM NE IB Jot E 1 0 Hi d i Li 51 Li Figure 1 2 MB23 amp MB25 Display Indicators Timing Setting Ohaus Corporation www ohaus com 1 4 MB23 and MB25 Service Manual CHAPTER 1 GETTING STARTED 1 5 3 Operating Modes Standby Mode When Analyzer is connected to AC power and display is off the unit is in Standby mode Short press Turns on the display and enters Weigh mode Weigh Mode The display shows the weight of items placed on the pan support Short press Sets the displayed weight value to zero Long press Enters Standby mode Off After power on the following operations can be initiated Short press Enters Edit mode for the temperature sett
4. Reading 6 Reading 7 Reading 8 Reading 9 Reading 10 10 Mean MB23 and MB25 Service Manual 4 3 Ohaus Corporation www ohaus com CHAPTER 4 FINAL TESTING 4 4 2 10 11 4 4 3 Repeatability Test Calculate the Delta for each reading and record it in the work sheet Delta Reading Mean Calculate the Delta x Delta for each reading and record in worksheet Add the ten Delta x Delta values and divide by 9 Calculate the Standard Deviation by applying the square root of the result from step 8 Standard Deviation Note If the Analyzer does not meet specifications move it to a suitable location ensure that it is level and try again If it still does not meet specifications calibrate the unit and try again See Appendix A for Calibration Linearity Test This test is used to determine the linearity of the unit throughout its operating range The masses used to perform this test can be utility masses Note Due to the use of relative weighing and limited use of the weighing range in moisture analysis linearity performance is not critical Linearity Test Mass Reference Mass 10g Load 1 10g Load 2 40g Load 3 90g NOTE All masses are nominal values Be certain to use the same reference mass throughout the procedure 1 Place the reference mass on the pan record the weight and remove Place Load 1 on the pan and press TARE Place the test mass on the pan record the weight and rem
5. OHRUS SERVICE MANUAL MB23 and MB25 Moisture Analyzers Ohaus Corporation 7 Campus Drive Suite 310 Parsippany NJ 07054 USA 973 377 9000 OHRUS SERVICE MANUAL MB23 and MB25 Moisture Analyzers 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 Material in this manual is subject to change Copyright 2010 Ohaus Corporation all rights reserved TM Registered trademark of Ohaus Corporation TABLE OF CONTENTS CHAPTER 1 GETTING STARTED Page No ee EE ME 1 1 L2 SONCE I me 1 1 1 3 Tools and Test Equipment 1 2 D MER eet m T 1 3 1 5 Analyzer ODS AOI sen Na Eus aS 1 4 ESL Overview OF tie COMMONS seiten tad eig 1 4 1 5 2 Overview of the Display Indicators eese 1 4 1 5 9 Operaung 1 5 1 54 POWE 1 7 155 E ROUTER 1 7 6 GOMIMUNICATIONS Merna E 1 8 CHAPTER 2 TROUBLESHOOTING TP FOUDISSMOOUNG nee el 2 1 2 1 1 General Procedures for Troubleshooting sees 2 1 eee nM 2 2 2 3 OIE SO VC ae ae fees 2 4 CHAPTER 3 MAINTENANC
6. Connector Plug on Power PCB Section 3 3 1 Reset Thermal Overload Device Section 3 8 6 Test Temperature Sensor Section 3 3 2 Test resistance in Temperature Sensor s plug receptacle Replace if resistance lt 1 000 Q Section 3 8 7 Replace Heater Section 3 8 5 Replace Power PCB Section 3 5 Replace Main PCB Section 3 6 Replace if resistance lt 1 000 Q Section 3 8 7 Replace Power PCB Section 3 5 Replace Main PCB Section 3 6 Ohaus Corporation www ohaus com CHAPTER 2 TROUBLESHOOTING Unstable weight Dirt or debris in unit Clean the unit thoroughly Cooling air current blocked Clean the ventilation grill Defective Load Cell Replace Load Cell Section 3 7 Defective Main PCB Replace Main PCB Section 3 6 Ohaus Corporation www ohaus com 2 4 MB23 and MB25 Service Manual CHAPTER 3 MAINTENANCE PROCEDURES 3 1 PREVENTIVE MAINTENANCE Ohaus moisture analyzers are precision instruments and should be carefully handled stored in a clean dry dust free area and cleaned periodically Follow these precautionary steps When a moisture analyzer has had chemicals or liquids spilled on it all exterior surfaces should be cleaned as soon as possible with warm water on a damp cloth leave a mass on the moisture analyzer when it is not in use Allow time for the moisture analyzer to stabilize after moving it from an area which is ata different temperature than the area where it is to
7. PCB 5 vde Fut Main Fuse FU2 PowerSupply Fuse Jump pins 11 to 18 The relay should close Measure voltage at CN2 It should read approx 120 vac 3 5 REPLACING THE POWER PCB Main Fuse Power Supply Fuse 1 2 Open the Housing See Section 3 2 Remove the Load Cell Cover See Section 3 3 Disconnect the cables from the fan temperature sensor heater and ground Disconnect the ribbon cable Remove the screws that secure the Power PCB to the bottom housing Install the replacement PCB insert the screws removed previously Figure 3 10 Power PCB Resassemble and calibrate See Appendix A Perform all tests See Chapter 4 MB23 and MB25 Service Manual 3 5 Ohaus Corporation www ohaus com CHAPTER 3 MAINTENANCE PROCEDURES 3 6 REPLACING THE MAIN PC BOARD 1 Open the Housing as explained in Section 3 2 ah E a UT 2 Disconnect the Load Cell cable from the Main PCB before lifting off the Load a acu Cell Cover im LUNG Si seed 3 Remove the four screws on the Load Cell Cover The two in the Power PCB are machine screws The two in the Main PCB are self tapping screws Note difference for re assembly 4 Lift off the Load Cell Cover ee Figure 3 11 Load Cell Cover 5 Disconnect power cable from the Main PCB 6 Remove two remaining screws that secure Main PCB to Bottom Housing 7 Lift out the Main PCB 8 Install the replacement Main PCB 9
8. Restore EEProm B 2 B 3 The Software Service Tool s Replace Load B 3 B 4 The Software Service Tool s Download Software B 4 B 5 The Software Service Tool s Diagnostics B 5 Ohaus Corporation www ohaus com iii MB23 and MB25 Service Manual TABLE OF CONTENTS MB23 and MB25 Service Manual IV Ohaus Corporation www ohaus com CHAPTER 1 GETTING STARTED 1 1 INTRODUCTION This service manual contains the information needed to perform routine maintenance and service on the MB23 and MB25 Moisture Analyzers Familiarity with the Instruction Manual is assumed The contents of this manual are contained in five chapters Chapter 1 Getting Started Contains information on service facilities tools specifications and the mechanical and electronic functions of the product Chapter 2 Troubleshooting Contains a diagnostic guide and error code table Chapter 3 Maintenance Procedures Contains preventive maintenance procedures and disassembly repair and replacement procedures Chapter 4 Testing Contains a list of required test masses an operational test segment display test performance tests and adjustments Chapter 5 Drawings and Parts Lists Contains exploded views of MB23 and MB25 Moisture Analyzers identifying all servi
9. SENICE Calba 559 nee B 5 LIST OF TABLES TABLE NO TITLE Page No 1 1 DOS CHIC ONS s 1 3 1 2 Functions of Display GOnIFols uii ne 1 4 2 1 Eror CodeS NN T s 2 2 2 2 PO DIS i SOV PN EU 2 4 4 1 Types of Performance Tests amp 4 1 5 1 MB23 amp MB25 Housing amp Internal 6 5 3 LIST OF ILLUSTRATIONS FIGURE NO TITLE 1 1 MB23 and MB25 Function Labels ea 1 4 1 2 MB23 amp MB25 Display nenne nenne nennen 1 4 1 3 AG de i gei 1 7 1 4 ROZSA DBO DIN MR oc EE 1 8 1 5 SOlder POS ON Co Bi ae eee ne ee een 1 8 3 1 MB25 with TOD OD CN ne ee 3 2 3 2 HOUSING Chamber nee ee nee 3 2 3 3 COE PIUG IMFIOUSINGk ea ce re 3 2 3 4 Glear Plastic muse eu Eu 3 2 3 5 Three Screws in Top FIOUSIPIO Sedit een ze 3 2 3 6 urung Me HOUS eee EHI PMID 3 9 3 7 Fan Temperature Sensor Heater cable connectors on Power PCB 3 3 3 8 Cables for Temperature Sensor Fan Ground and Heater disconnected 3 4 3 9 Power PGB CONNECIOTS sasea seen 3 5 3 10 POWer PO C M 3 5 3 11 koad Gell GOVOLP assessed tase teh TEN ei ete eM 3 6 3 12 Main Printed GIreult Board Mec E 3 6 3 13 Display UCD on Main t Oed reed ee
10. Service Manual OHRUS 8 0 2 5 2 4 6 9 P N 80252469 A SERVICE MANUAL MB23 amp MB25 MOISTURE ANALYZERS
11. affect the results of the Precision Test Inspect and correct if necessary See Off Center Load Test 3 Foreign material or debris between the pan and the base will cause the Analyzer to fail the test 4 Vibrations drafts or a non level surface can cause failures Ohaus Corporation www ohaus com 4 2 MB23 and MB25 Service Manual CHAPTER 4 FINAL TESTING 4 4 2 Repeatability Test Repeatability is the Standard Deviation of a set of similar readings Requirements To perform this test identical samples must be used for all readings The test sample should be approximately 50 grams Wear gloves when handling the sample Before starting a repeatability test set up the instrument as follows TEST PROCEDURE 1 Zero the instrument 2 Using atest sample of approximately 50 grams place the sample on the center of platform Record the reading on the worksheet provided 3 Remove the sample from the platform Repeat this test starting at Step 1 until you record a total of ten readings Fill in the worksheet Table 4 2 with the ten 10 readings TABLE 4 2 REPEATABILITY WORKSHEET a _ Delta Reading Mean Delta x Delta n number of Reading Mean Sum of readings 10 Delta Reading Mean Standard Deviation Square Root of sum of Delta x Delta 9 5 Add the ten readings and divide the total by 10 to find the Mean average 6 Mean Reading 1 Reading 2 Reading 3 Reading 4 Reading 5 7
12. et dans 3 6 3 14 koad a E 3 7 3 15 Load Cell with Ribbon Cable Attached at Bottom 3 7 3 16 Screws Holding Chamber Top to the Heater Frame Housing 3 8 MB23 and MB25 Service Manual i Ohaus Corporation www ohaus com TABLE OF CONTENTS FIGURE TITLE Page No 3 17 Separating the Chamber Top from the Heater Frame Housing 3 8 3 18 Testing Heater Leads Resistance 3 8 3 19 Screws and Washers that Secure the 3 9 3 20 MB23 Screws and washers anchoring cables on each side of Heater 3 9 3 21 Spring TaD ON GONNMECCIOM nee el 3 9 3 22 Iarting Outthe Mealer MB2S Ede eii aea eee ota eh aite seios 3 9 3 23 Screw and washer anchoring Heater 3 10 3 24 Lifting Out the Heater MB25 cece ccccceeeecceeeeseeeeseecesseeeeseeeesaesessueessaeeesans 3 10 3 25 MB23 Installing the Heater iui adidas en 3 11 3 26 Reset Button on the Thermal Overload 3 11 3 27 MB25 Thermal Overload Device 3 12 3 28 MB23 Thermal Overload Device 3 12 3 29 MB 25 Thermal Overload Devi
13. 2 2 MB23 and MB25 Service Manual CHAPTER 2 TROUBLESHOOTING TABLE 2 1 ERROR CODES ERROR PROBABLE CAUSE REMEDY Cycle power Err 53 EEPROM Checksum error Defective ribbon cable Main PCB defective 2 3 Problem Solver Check cable from Main PCB to Load Cell Replace Main PCB Section 3 6 TABLE 2 1 PROBLEM SOLVER Cannot turn on power supply voltage Defective main fuse Defective power supply fuse Defective Power PCB Cable connections inside instrument not plugged in or defective Defective Main PCB Power cord not plugged in or no Verify connections and voltage Check fuse on back of instrument Replace power supply fuse Figure 3 10 Replace Power PCB Section 3 5 Plug in or replace cable Replace Main PCB Section 3 6 Portions of display Defective display Replace Display LCD do not light up Defective Main PCB Replace Main PCB Cannot calibrate Unstable environment Move unit to suitable location Incorrect calibration masses Use correct calibration masses Defective Heater connection or cable Thermal Overload Device has tripped Defective temperature sensor cable Heater does not switch on after Start Defective Temperature Sensor Defective Heater Defective Power PCB Defective Main PCB Temperature rises above 180 C Defective Power PCB Defective Main PCB MB23 and MB25 Service Manual 2 3 Defective Temperature Sensor Test resistance at Heater
14. 8 4 Stop Bits 1 2 5 Handshake None XON XOFF RTS CTS DB9 Connections Pin 1 Jumper required J2 for Remote Tare operation Pin 2 Balance transmit line TxD Pin 3 Balance receive line RxD Pin 4 Shorted to Pin 6 Pin 5 Ground signal GND Pin 6 Shorted to Pin 4 Pin 7 Clear to send hardware handshake CTS Pin 8 Request to send hardware handshake RTS Pin 9 Jumper required J1 for Remote Print operation Figure 1 4 RS232 DB9 pin setup AN Note After installing the jumper for remote operation ensure that wires are protected from static discharge To enable External PRINT and or ZERO TARE functions join the solder points for Tare J2 and Print J1 on the Main PCB 1 Locate solder points J1 and J2 on the Main PCB above the Display LCD 2 Using a low wattage soldering iron apply a small amount of solder to Join two points at J2 to enable Tare Join two points at J1 to enable Print Join the points by filling the gap Ohaus Corporation www ohaus com 1 8 MB23 and MB25 Service Manual CHAPTER 2 TROUBLESHOOTING 2 1 TROUBLESHOOTING This section of the manual provides a standard troubleshooting methodology Follow all directions step by step Make certain that the work area is clean Handle components with care Use an Electro Static Device 2 1 1 General Procedures for Troubleshooting 1 2 3 4 Do the most obvious user level remedies
15. Check that internal parts are clean and free of debris Consult the Error Code Table Table 2 1 for solutions to specific codes Use the Problem Solver Table 2 2 to locate the symptom Follow the suggested remedies in the order they appear Visual Check Examine the Load Cell for signs of bending twisting or corrosion Clean the unit before evaluating any mechanical problems Remove any debris inside the Housing Examine the Housing for damage bent parts or signs of physical abuse Replace all damaged parts See Chapter 5 for parts list Check the cables leading to the Load Cell for cuts abrasions or other signs of damage Examine the Load Cell for corrosion due to high humidity or exposure to chemicals A Load Cell that is even slightly bent or corroded should be replaced Check the heating unit for corrosion or other damage If a problem arises that is not covered in this manual contact your local Ohaus office MB23 and MB25 Service Manual 2 1 Ohaus Corporation www ohaus com CHAPTER 2 TROUBLESHOOTING 2 2 Error Codes When a problem occurs the display may indicate an error code Table 2 1 describes the various error codes and specifies the probable cause and remedy TABLE 2 1 ERROR CODES ERROR PROBABLE CAUSE REMEDY Err 7 0 Time out Turn unit off and then back on Defective Main PCB Replace Main PCB Section 3 6 Err 8 1 Pan Support has load during Remove weight from Pan Support power on Dirt or debris in un
16. E PROCEDURES Sal iPrevernuve sVvialtellanibe EY e uat usu Grane Meade o Radio Qus 3 1 3 1 1 Preventive Maintenance Checklist 3 1 2 2 Opening ihe MB23 and MB25 iiia Gc eet 3 1 3 3 Preliminary Checks of the Top Housing 3 4 9 9 1 Testthe Heater anreisen ende 3 4 3 3 2 Test the Temperature Sensor and 3 4 CC OMNE Mmi E UT UP 3 4 3 3 4 Test the Ground Circuit on the 23 3 4 34 Testing the Power P OD ee e P asl quate d CUL a DRUMS 3 5 3 5 Replacing the POWER POB leeres 3 5 3 6 Replacing the Main PG Board Eus 3 6 Replacing the Display EG Disk 3 6 o dmepacindheLoad Belkin sanieren est ual tial dunt 3 7 3 8 Repairing and or Replacing the Heating Unit 3 8 3 9 1 Testing the Heater aa en Cra 3 8 3 8 2 Removing the Heater on the 23 3 9 3 8 3 Removing the Heater on the MB25 essere nennen nnn 3 10 3 8 4 Replacing the Heater the MB25 3 10 3 8 5 Replacing the Heater on the 23 3 11 3 8 6 Testing the Thermal Overload
17. Loadcell MB Series Service Tool E inl x File Settings Help Restore EEPROM Download Software Syn Model Number Figure B 3 The Software Service Tool s Replace Load Cell Tab 5 Enter the Serial Number from the label on the bottom of the Analyzer 6 Click the Start button 7 The software will indicate the download progress When complete disconnect the power from the back of the Analyzer then re connect 8 Perform Service Calibrations see Section B 5 Test the Analyzer MB23 and MB25 Service Manual B 3 Ohaus Corporation www ohaus com APPENDIX B SOFTWARE SERVICE TOOL INSTRUCTIONS B 3 Update the Software in the Analyzer 1 Connect the Analyzer to your computer 2 Start the Software Service Tool Software 3 Click on the tab labeled Download Software 2 MB23 MB25 Series Service Tool V1 10_B Mot File To Download To Scale F MB23 25sw 020210 83020540H 5R1 07 mot Download Mot File To Scale Downloading Software please wait Figure B 4 The Software Service Tool s Download Software Tab 4 Enter the path to the file to download or click the Change button to locate the file 5 Click the Start Download button 6 When prompted disconnect the power from the back of the Analyzer then re connect 7 The software will indicate the download process When complete disconnect the power from the back of the Analyzer then re connect 8 Perform Service Calibrations see Section B 5 T
18. ROCEDURES 3 8 8 Replacing the Fan The fan is located in the Top Housing To access it remove the Top Housing as explained in Section 3 2 The follow these steps 1 Turn the Heater Unit over and remove the two screws that secure the Fan Plate See Figure 3 30 4 Liftthe Fan Plate and slide out the cable grommets one each from the left and right sides See Figure 3 31 Figure 3 31 Grommets slide out from the Fan Plate 5 Lift out the Lid Position Rod and spring from under the Fan Plate See Figure 3 32 6 Draw the cable connectors through the holes in the housing and set them aside Note After reinstalling Lid Position Rod test its spring action when closing the Heater Unit on the Top Housing Figure 3 32 Lid Position Rod and Spring under the Fan Plate 7 Lift out the Fan See Figure 3 33 8 Gently press back on the Heater Frame Housing first on one side then on the other to release it from the Top Housing 9 Install the replacement Fan by following these steps in reverse Figure 3 33 Removing the Fan MB23 and MB25 Service Manual 3 13 Ohaus Corporation www ohaus com CHAPTER 3 MAINTENANCE PROCEDURES 3 8 9 Replacing the Temperature Sensor 1 2 10 11 12 13 Remove the Reflector and Heater as explained in Section 3 9 2 Remove the screw and washer that secure the Temperature Sensor Cable See Figure 3 34 Lift the Temperature Sensor Cable out of
19. Reassemble the Moisture Analyzer 10 Calibrate the Moisture Analyzer du See Appendix A Perform all tests Figure 3 12 Main Printed Circuit Board See Chapter 4 3 6 1 Replacing the Display LCD 1 Follow steps 1 6 in Section 3 7 2 Note location of backlight cables then remove them 3 Cutthe leads from the old LCD remove the old LCD 4 Remove the remaining lead wires clean solder from the holes 5 Install new backlight LCD Position Figure 3 13 Display LCD on Main PCB backlight cables like originals and solder in place 6 Soldier in the LCD leads Ohaus Corporation www ohaus com 3 6 MB23 and MB25 Service Manual CHAPTER 3 MAINTENANCE PROCEDURES 3 REPLACING THE LOAD CELL 10 11 Open the Housing as in Section 3 2 remove the Load Cell Cover as in Section 3 3 Remove the ribbon cable that connects the two PCBs Figure 3 14 Remove the four screws that secure the Load Cell Carefully lift up the Load Cell not all the way See next step Hold the Load Cell with one hand and gently lift out the ribbon cable from the groove that secures it to the Bottom Housing See Figure 3 15 Lift out the Load Cell Disconnect the ribbon cable from the old Load Cell and connect it to the replacement Load Cell Install the new Load Cell by reversing the steps above Reassemble the Moisture Analyzer Install the Load Cell using the Software Service Tool See Appe
20. Top on the Heater Frame Housing Insert the four screws that secure Chamber Top to the Heater Frame Housing See Figure 3 16 Figure 3 24 Lifting out the Heater Repeat Heater Circuit Tests See Section 3 3 1 If tests are OK reassemble the Top Housing See Section 3 8 Perform a Temperature Calibration See Appendix A Ohaus Corporation www ohaus com 3 10 MB23 and MB25 Service Manual 3 8 5 Replacing the Heater on the MB23 1 6 T 8 CHAPTER 3 MAINTENANCE PROCEDURES Grasp the new Heater by its base and gently press it into the retainer clips opposite See Figure 3 25 Insert the base into the slots Connect the Heater cables Install the Reflector Replace the Chamber Top on the Heater Frame Housing Insert the four screws that secure Chamber Top to the Heater Frame Housing Figure 3 25 MB23 Installing the Heater Repeat Heater Circuit Tests See Section 3 3 1 If tests are OK reassemble the Top Housing See Section 3 8 Perform a Temperature Calibration See Appendix A 3 8 6 Testing the Thermal Overload Device 1 Remove the Chamber Top Section 3 9 1 Steps 1 and 2 and the Reflector Section 3 9 2 Step 1 Perform a continuity test on the Thermal Overload Device with power to the unit off use an ohm meter to measure resistance between the device s poles Resistance should be zero If so the device is good If not proceed to Step 3 Press the device s reset butt
21. and apply power 2 Connect pins 18 and 13 on Power PCB Connector CN3 See Section 3 4 Fan should run Disconnect power before proceeding 3 Iffan does not run apply external power to fan If fan runs replace the Power PCB 3 3 4 Test the Ground Circuit on the MB23 1 Connect one probe to the Ground Cable plug and the other to the Heater 2 Measure resistance It should be approximately zero Ohaus Corporation www ohaus com 3 4 MB23 and MB25 Service Manual CHAPTER 3 MAINTENANCE PROCEDURES 3 3 4 Test the Ground Circuit on the MB23 continued 3 Open and close close Top Housing to check for an intermittent cable problem If resistance remains zero the Ground cable is good If not replace it 3 4 TESTING THE POWER PCB Check Power Supply Fuse CN6 If defective replace PCB ES Disconnect all cables BE Suede Apply power CAUTION WHEN CONDUCTING TESTS WITH POWER ON BE EXTREMELY CAREFUL TOUCHING PCB COMPONENTS WITH POWER ON MAY CAUSE SERIOUS INJURY Check Main Fuse Replace if necessary For steps 5 7 refer to connector CN3 Connect probes to pins 20 and 18 it should read 5 vdc CN3 Connect probes to pins i Pin 20 10 and 18 and insert the Lid Position Rod between Figure 3 9 Power PCB connectors D and E Reading should be approx 3 vdc RS232 Port AC Adapter Jump pins 13 to 18 Measure Temperature Sensor voltage at CN6 It should read CN6 Fan To Main
22. be operated Allow one hour for each 5 F 2 7 C temperature change before using the Analyzer After temperature stabilization allow an additional 20 minutes after turning the unit on for the electronics to stabilize 3 1 1 Preventive Maintenance Checklist The moisture analyzer should be inspected and checked regularly as follows 1 Remove the Pan Handler Pan Support and Draft Shield to inspect and clean the area beneath the Pan 2 Clean the outside using a damp cloth with warm water CAUTION N DO NOT USE CHEMICAL CLEANERS OR SOLVENTS OF ANY TYPE SOME CLEANERS ARE ABRASIVE AND MAY AFFECT THE FINISH 3 Check the Power Cord for broken or damaged insulation 4 Make a visual inspection for faulty connectors wiring and loose hardware 3 2 OPENING THE MB23 AND MB25 Common hand tools are sufficient to disassemble the MB23 and MB25 moisture analyzers Turn the Analyzer off and unplug the power cord before you begin Warning Disconnect from power supply and allow heating module to cool AN Use electrostatic protection when servicing Electrostatic damage is difficult to detect because the faults it causes are not clear cut MOS switching transistors with electrostatic damage have substantially higher thermically unstable leakage currents As a result the Moisture Analyzer Analyzer drifts more and the display can fluctuate similar to when there is a draft To avoid electrostatic damage during production conducting floors control
23. ce 3 12 3 30 Screwsdh Fat Plale sn nee 3 13 3 31 Grommets Slide Out from the Bottom 3 13 3 32 Lid Position Rod and Spring under the Fan Plate 3 13 3 33 NE EAE een 3 12 3 34 Removing Screw to Access Temperature Sensor Cable 3 14 3 35 Removing Clip that Secures Heater with Needle Nose Pliers 3 14 3 36 Removing Screws and Washers Securing Temperature Sensor 3 14 3 37 Connecting Cables to the Power 3 15 3 38 Facing Plug on Housing a a 3 15 3 39 Installing Protective Glass een pedi 3 15 3 40 Clear plastic In use Cover uuuessssseeesnsnnnennnennnnnnnennnnnnnnnnnnnnnnnnnnnnnnnnnneennnnnne nnns 3 16 3 41 een a ee ee 3 16 3 42 MB25 WITH LOD ODE Noeren aa 3 16 4 1 SEGMeNt DISMAY RE EH 4 1 5 1 MB23 amp MB25 Housing amp Internal 5 2 1 Temperature Calibration Kit installed 002222200022200000 Rennen nennen een A 1 B 1 Gom Port Configuration Menu oido ico E 1 2 The Software Service Tool s
24. ceable components Appendix A Standard Calibration Explains procedures for Standard Calibration performed prior to use and after service 1 2 SERVICE FACILITIES The service area should meet the following requirements e Should be temperature controlled and meet specifications for temperature environmental requirements Must be free of vibrations such as fork lift trucks close by large motors air currents or drafts from air conditioning heating ducts open windows people walking by fans etc e Area must be clean and free of excessive dust e Work surface must be stable and level e Moisture Analyzers must not be exposed to direct sunlight or radiating heat sources e Use an approved Electro Static Device MB23 and MB25 Service Manual 1 1 Ohaus Corporation www ohaus com CHAPTER 1 GETTING STARTED 1 3 TOOLS AND TEST EQUIPMENT REQUIRED Digital Voltmeter DVM Input impedance of at least 10 megohms in 1 Volt dc position Standard electronics tool kit Soldering iron 50 watt and solder rosin core solder not acid core Solder remover Ohaus Temperature Calibration Kit P N 11113857 50g calibration weight Strain Gage Simulator optional Soft lint free cleaning cloth Anti static bags for PCBs 10 Anti static wrist strap and mat 11 RS232 Cable P N 80500525 ue lO ee deme qa x Ohaus Corporation www ohaus com 1 2 MB23 and MB25 Service Manual 1 4 SPECIFICATIONS CHAPTER 1 GETTING STARTED Com
25. er PCB 3 Install the Top Housing 4 Double check that the grommet seal in the center of the Top Housing rests smoothly If it is twisted reopen the Housing to set it straight Otherwise the display will show Err 8 3 on power up 5 Insert the three screws to secure the top housing See figure 3 38 6 Place the small plug over the front screw after tightening it as shown 7 Ifthe Protective Glass on the MB25 was removed or replaced install it as follows 8 Place the Protective Glass in the groove in the Heater Frame Housing in front of the Heater 9 Then place the retainer clips and screws in the holes provided to secure the glass See Figure 3 39 Figure 3 39 Installing Protective Glass MB23 and MB25 Service Manual 3 15 Ohaus Corporation www ohaus com CHAPTER 3 MAINTENANCE PROCEDURES 3 9 INSTALLING THE TOP HOUSING continued 10 Place the clear plastic In use Cover on top of the Function Label 11 Push in the Housing Chamber Figure 3 40 Clear plastic In use Cover Figure 3 41 Housing Chamber Pan 12 Install the Pan Handler Pan Support Handler and Cleanout Tray See Figure 3 42 Cleanout Tray Figure 3 42 MB25 with top open Ohaus Corporation www ohaus com 3 16 MB23 and MB25 Service Manual CHAPTER 4 FINAL TESTING 4 1 FINAL TESTING Before servicing the MB23 or MB25 Moisture Analyzer an operational test and various performance tests should be done to de
26. est the Analyzer Ohaus Corporation www ohaus com B 4 MB23 and MB25 Service Manual APPENDIX B SOFTWARE SERVICE TOOL INSTRUCTIONS B 4 Diagnostics 1 Connect the Analyzer to your computer 2 Start the Software Service Tool 3 Click the tab labeled Diagnostics MB Series Service Tool inl x File Settings Help Restore EEPROM Replace Loadcell Download Software Command String Send Print Service Calibration Cancel Calibration Figure B 5 The Software Service Tool s Diagnostics Tab 4 test communications click Print or enter an RS232 Command String and click Send 5 The Analyzer s response will be shown in the box on the right B 5 Perform Service Calibration Note This procedure requires a 50g calibration mass Available from Ohaus If a calibration mass is unavailable after calibration starts click Cancel Calibration 1 Click the Service Calibration button Click Cancel Calibration to stop the process 2 Place the 50g calibration mass on the platform when prompted Calibrati 3 Remove the mass when prompted ancel Calibration The Analyzer returns to weighing mode Successfully done Note Service Calibration is also possible without the Software Service Tool see Appendix A MB23 and MB25 Service Manual B 5 Ohaus Corporation www ohaus com APPENDIX B SOFTWARE SERVICE TOOL INSTRUCTIONS Ohaus Corporation www ohaus com B 6 MB23 and MB25
27. ing the value will blink Short press Enters Edit mode for the time setting the value will blink Short press Activates Run mode initiates test with sample greater than 0 59 Long press Initiates weight or temperature Calibration See Appendix A Temperature Time Edit Mode Preparing a Test Temperature editing 50 to 160 C in 5 steps Short press Enters Edit mode for the temperature setting the value will blink Short or long press Increases the value of the temperature setting Short or long press Decreases the value of the temperature setting Short press Accepts the blinking value and returns to Weigh mode lt gt DWO Short press Exits Edit mode without saving changes Note After 5 seconds of no activity the blinking setting is automatically saved and the mode returns to Weigh mode Time editing 1to 60 minutes in 30 second steps 61 to 99 minutes in 1 minute steps The time parameter can be set to timed duration or AUTO test ends when Analyzer detects the weight loss has ended Selecting AUTO or timed duration Short press Enters Edit mode for the time setting The value will blink Short press while time setting blinks Toggles between AUTO and time value Accepts the blinking setting If AUTO is selected Weigh mode is entered MB23 and MB25 Service Manual 1 5 Ohaus Corporation www ohaus com CHAPTER 1 GETTING STARTED 1 5 3 Operating Modes continued If Time D
28. it Clean the unit thoroughly Defective Load Cell Replace Load Cell Section 3 7 Defective Main PCB Replace Main PCB Section 3 6 Err 8 2 Pan Support removed during Install Pan Support power on or dirty Pan Support Be sure it s clean Load Cell defective Replace Load Cell Section 3 7 Main PCB defective Replace Main PCB Section 3 6 Err 8 3 Weight on Pan Support exceeds Remove weight from Pan Support Capacity Perform troubleshooting steps Dirt or debris in unit Clean the unit thoroughly Err 8 4 Pan Support was removed Re install Pan Support during weighing Perform troubleshooting steps Dirt or debris in unit Clean the unit thoroughly Err 9 5 Factory calibration data Use Software Service Tool to restore corrupted EEPROM Appendix B Err 10 3 Temperature Sensor out of Check Replace cables Section 3 3 2 range high Check Replace Sensor Section 3 8 9 Replace Main PCB Section 3 6 Err 10 4 Temperature Sensor out of Check Replace cables Section 3 3 2 range low Check Replace Sensor Section 3 8 9 Replace Main PCB Section 3 6 Err 10 5 Temperature Sensor defective Check Replace cables Section 3 3 2 Check Replace Sensor Section 3 8 9 Replace Main PCB Section 3 6 Err 10 6 Temperature Sensor defective Check Replace cables Section 3 3 2 Check Replace Sensor Section 3 8 9 Replace Main PCB Section 3 6 Err 11 0 AC power is unstable Use a Power Line Conditioner Ohaus Corporation www ohaus com
29. led air humidity and EMC mats are used When servicing the unit it is also advisable as soon as the instrument is opened to neutralize electrostatic charges MB23 and MB25 Service Manual 3 1 Ohaus Corporation www ohaus com CHAPTER 3 MAINTENANCE PROCEDURES 3 2 OPENING THE MB23 AND MB25 continued 1 Lift the top Pan Handler 2 Remove the Pan Handler Pan Support and Cleanout Tray See Figure 3 1 Pan Support 3 Pull away the Housing Chamber Cleanout Tray Figure 3 2 Housing Chamber 4 Lift out the plug in the Housing 5 Remove the clear plastic In use Cover that protects the Function Label Figure 3 4 Clear plastic In use Cover Figure 3 3 Lifting out plug in Housing 6 Remove the three screws in the Top Housing See Figure 3 5 Figure 3 5 Three screws in Top Housing Ohaus Corporation www ohaus com 3 2 MB23 and MB25 Service Manual CHAPTER 3 MAINTENANCE PROCEDURES 3 2 OPENING THE MB23 AND MB25 continued 7 Gently lift the Top Housing so the rear stays in place and the front rises See Figure 3 6 8 Remove the three cables connected to the Power PCB Figure 3 7 9 On the MB23 disconnect the ground wire Not necessary on the MB25 10 Lift the Top Housing off and set it aside MB23 and MB25 Service Manual 3 3 cable connectors on Power PCB Ohaus Corporation www ohaus com CHAPTER 3 MAINTENANCE PROCEDURES 3 3 PRELIMINARY CHECKS OF THE TOP HOUSING COMPONENTS S
30. ndix B Calibrate the Moisture Analyzer See Appendix A and Perform all tests See Chapter 4 attached at bottom MB23 and MB25 Service Manual 3 7 Ohaus Corporation www ohaus com CHAPTER 3 MAINTENANCE PROCEDURES 3 8 REPAIRING AND OR REPLACING THE HEATING UNIT PARTS 1 Remove the four screws that secure the Chamber Top to the Heater Frame Housing See Figure 3 16 2 Use a flathead screwdriver to gently pry the Chamber Top from the Heater Frame Housing See Figure 3 17 Figure 3 16 Screws holding Chamber Top to the Heater Frame Housing Figure 3 17 Separating the Chamber Top from the Heater Frame Housing 3 8 1 Testing the Heater Circuit 1 Perform a Resistance Test With power to the unit off use an ohm meter to measure resistance between the Heater s leads Resistance should be approximately 45 ohms for the MB23 and approx 5 7 ohms for the MB25 2 Move the cables while checking to test for an intermittent cable problem Read ings should not fluctuate during this test 3 If OK test Thermal Overload Device Hs gm See Section 3 9 4 Figure 3 18 Testing Heater leads 4 If Thermal Overload Device is OK check resistance fuses on Power PCB 5 If fuses are OK replace Power PCB Ohaus Corporation www ohaus com 3 8 MB23 and MB25 Service Manual CHAPTER 3 MAINTENANCE PROCEDURES 3 8 2 Removing the Heater on the MB23 1 Remove the screws and washers that secure the Reflect
31. ome problems can be identified by testing resistance on cable connector plugs immediately after opening the Housing the Temperature Sensor Heater Fan and Ground circuit on the MB23 It is also possible at this stage to test the Power PCB and Main PCB m Figure 3 8 Cables for Temperature Sensor Fan Ground and Heater disconnected Note MB23 shown MB25 does not require ground cable for heating element 3 3 1 Test the Heater Circuit 1 Measure resistance on Heater connector plug insert probes into plug See Fig 3 8 If there is no continuity Thermal Overload Cables or Heater may be defective 2 Open and close Top Housing while checking for an intermittent cable problem Readings should not fluctuate during this test 3 Perform tests on Power PCB see Section 3 4 next page 3 3 2 Test the Temperature Sensor and Cable 1 Connect probes to the Temperature Sensor Cable s plug See Figure 3 8 2 Measure resistance it should be approximately 1 000 O 3 Open and close the Top Housing while checking for an intermittent cable problem Readings should not fluctuate during this test 4 lf resistance and flex tests 2 8 above are OK the Temperature Sensor is good If not replace the cable or sensor See Section 3 9 7 CAUTION WHEN CONDUCTING TESTS WITH POWER ON BE EXTREMELY CAREFUL TOUCHING PCB COMPONENTS WITH POWER ON MAY CAUSE SERIOUS INJURY 3 3 3 Test the Fan 1 Connect AC cord to the analyzer
32. on See Figure 3 26 Then re test If test fails replace the device Reassemble the Heating Unit Perform a Temperature Calibration See Appendix A Conduct Performance Tests Figure 3 26 Reset button on the Thermal See Chapter 4 Overload Device MB23 and MB25 Service Manual 3 11 Ohaus Corporation www ohaus com CHAPTER 3 MAINTENANCE PROCEDURES 3 8 7 Replacing the Thermal Overload Device 1 Remove the Chamber Top and Reflector Sections 3 9 1 and 3 9 2 Remove the cables from the Thermal Overload Device by pressing on the tiny spring with the end of a small flat head screwdriver See Figure 3 21 If the Thermal Overload Device has been disassembled insert its bolt through the hole in the base of its blade See Figure 3 27 Fit the washer and then the nut and use a wrench to tighten the nut MB23 Mount the ground cable ring See Figure 3 28 Then use a wrench to tighten the nut Insert Thermal Overload Device into the grooves provided on the Housing Connect the cables to the Thermal Overload as shown in Figure 3 29 Reassemble the Heating Unit Perform a Temperature Calibration See Appendix A Conduct Performance Tests See Chapter 4 Ohaus Corporation www ohaus com 3 12 Figure 3 27 MB25 Thermal Overload Device Figure 3 28 MB23 Thermal Overload Device Figure 3 29 MB25 Thermal Overload installed MB23 and MB25 Service Manual CHAPTER 3 MAINTENANCE P
33. on pan _ a Clear pan N y o ml Place weight on pan Place weight on pan 500 8000 Place weight pan Clear pan 7 Mg Place weight on pan Clear pan EN E es MB23 and MB25 Service Manual A 3 Ohaus Corporation www ohaus com APPENDIX A STANDARD CALIBRATION Ohaus Corporation www ohaus com A 4 MB23 and MB25 Service Manual APPENDIX B SOFTWARE SERVICE TOOL INSTRUCTIONS APPENDIX B SOFTWARE SERVICE TOOL INSTRUCTIONS The Software Service Tool is used for five purposes 1 2 3 4 5 To restore EEPROM data after EEPROM corruption To install a new Load Cell To update the software in the Analyzer For diagnostics To perform Service Calibration Install the software on a Personal Computer running Microsoft Windows NT 4 0 or later Insert the CD or download the software and run Setup exe After installation run the program Service Tool The program has 5 tabs across the top of the screen Click 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 w Com Port Configuration X Fart com Baudrate Data Parity stop bits Flow control Detaults Cancel Lik Figure B 1 Com Port Configuration Menu MB23 and MB25 Service Manual B 1 Ohaus Corpo
34. or and lift it NA off See Figure 3 19 N ah f Figure 3 19 Screws and washers that secure the Reflector 2 Remove the screws and washers that secure the Heater gt See Figure 3 20 3 Release the lead connectors on the Heater cables by pressing on the tiny spring tab with the end of a small flat head screwdriver Springtab to F release Lead Pa e connectors Figure 3 20 MB23 Screws and washers anchoring cables on each side of Heater Figure 3 21 Connector Spring Tab 4 Grasp the Heater s base and lift it up and out See Figure 3 22 This will release the Heater from the retainer clips opposite Retainer clips Figure 3 22 Lifting out the Heater MB23 and MB25 Service Manual 3 9 Ohaus Corporation www ohaus com CHAPTER 3 MAINTENANCE PROCEDURES 3 8 3 Removing the Heater on the MB25 1 3 8 4 Replacing the Heater on the MB25 1 Remove the screws and washers that secure the Reflector and lift it off See Figure 3 19 Remove screw and washer anchoring the cable See Figure 3 23 Figure 3 23 Screw and washer anchoring Heater Cables Press outwards on the clips on both sides of the Heater and lift the Heater up and out Figure 3 24 Grasp the new Heater by its base gently press it against the retainer clips opposite and press it down until it clicks into place Connect the Heater cables Install the Reflector Replace the Chamber
35. ove Place Load 2 on the pan and press TARE Place the test mass on the pan record the weight and remove Place Load 3 on the pan and press TARE Place the test mass on the pan and record the weight po SS XE ID The difference in the weights of the test mass should be within the Linearity tolerance in Table 1 1 If not calibrate see Appendix A 1 and repeat the test 9 If the unit remains out of tolerance the Load Cell may need to be replaced Ohaus Corporation www ohaus com 4 4 MB23 and MB25 Service Manual CHAPTER 5 PARTS LISTS amp DIAGRAMS This section of the manual contains exploded views for the MB23 and MB25 Moisture Analyzers The exploded view drawings are designed to identify the parts which can be serviced on the Analyzer in the field NOTE In all cases where a part is replaced the Analyzer must be thoroughly checked after the replacement is made The Analyzer 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 NY 07054 USA Tel 973 377 9000 Fax 973 593 0359 In the United States call toll free 800 526 0659 between 8 00 a m and 5 30 p m EST MB23 and MB25 Service Manual 5 1 Ohaus Corporation www ohaus com MB23 amp MB25 HOUSING amp INTERNAL PARTS CHAPTER 5 PARTS LISTS amp DIAGRAMS 9 1
36. plete specifications for the Ohaus MB23 and MB25 Moisture Analyzers are listed in Table 1 1 When a scale has been serviced it must meet these specifications TABLE 1 1 SPECIFICATIONS Model MB25 MB23 Capacity 110g Ropetaity Don ee 997e Readability requires gt 10g sample 0 005g 0 05 0 019 0 1 Linearity d 2 Off Center Load 5 cap 2 dist 5d Tare range To capacity by subtraction Stabilization Time lt 3 seconds Calibration Weight External Calibration Mass 50g Calibration Temperature OHAUS Temperature Calibration Kit Temperature Settings 50 C to 160 C 5 increments Temperature Readability Temperature Repeatability Thermal Overload Protection 5 C 5 C Bimetalic element switch in dryer unit Temperature Adjustments 2 points 100 C and 160 C Operating Temperature Range 41 F to 104 5 C to 40 C Operating Humidity Range 10 85 RH non condensing Shipping amp Storage Temp 40 C 40 F to 60 C 140 F at 10 to 95 non condensing Heating Technology Power Requirement Halogen Infrared no glass 100 to 240 VAC 50 60 Hz MB23 and MB25 Service Manual Ohaus Corporation www ohaus com CHAPTER 1 GETTING STARTED 1 5 ANALYZER OPERATION This section contains information on the basic operation of the scale 1 5 1 Overview of the Controls s
37. power cable to the power input receptacle at the rear of the Analyzer and into a properly grounded power outlet Figure 1 3 AC power Follow these safety precautions when servicing or using the Moisture Analyzer The Analyzer has a 3 pin power cable that includes a ground connection Intentionally disabling the equipment grounding connection is prohibited Disconnect the Analyzer from the power supply when cleaning 1 5 5 Power On amp Off On short press Off Standby Mode long press When powered on from standby mode Analyzer is ready for immediate use Allow time for the Analyzer to stabilize after moving it from an area which is at a different temperature than the area where it is to be operated Allow one hour for each 5 F 2 7 C temperature change before using the unit After temperature stabilization allow an additional 20 minutes after turning the unit on for the electronics to stabilize When the scale is first turned on the factory default is to weigh in grams and tare items without setting the menus MB23 and MB25 Service Manual 1 7 Ohaus Corporation www ohaus com CHAPTER 1 GETTING STARTED 1 6 Communications Interface The MB23 and MB25 are equipped with a bi directional RS232 interface accessed through a DB9 pin connector on the rear of the unit Following are available parameters defaults in bold 1 Baud Rate 1200 2400 4800 9600 19 200 2 Parity Odd Even None 3 Data Bits 7
38. ration www ohaus com APPENDIX B SOFTWARE SERVICE TOOL INSTRUCTIONS B 1 To Restore the EEPROM data 1 Record the Serial Number and Model Number from the label on the bottom of the Analyzer to be repaired 2 Contact Ohaus Corporation in Pine Brook NJ and request the data file to download Provide the information recorded above 3 After receiving the data file from Ohaus continue with the following steps 4 Connect the Analyzer to the PC and start the Software Service Tool 5 Click the tab labeled Restore EEPROM MB Series Service Tool inl x File Settings Help Replace Loadcell Download Software Image File Change Write Image File Figure B 2 The Software Service Tool s Restore EEProm Tab 6 Enter the Analyzer s Serial Number 7 Enter the path to the image file or click the Change button to locate the file 8 Click the Write Image File button 9 The software will indicate the download progress When complete disconnect the power from the back of the Analyzer then re connect 10 Perform Service Calibrations see Section B 5 Test the Analyzer Ohaus Corporation www ohaus com B 2 MB23 and MB25 Service Manual APPENDIX B SOFTWARE SERVICE TOOL INSTRUCTIONS B 2 To Replace a Load Cell 1 Follow the steps in Section 3 2 to replace the defective load cell 2 Connect the Analyzer to your computer 3 Start the Software Service Tool Software 4 Click on the tab labeled Replace
39. t Analyzer returns to Weigh mode MB23 and MB25 Service Manual A 1 Ohaus Corporation www ohaus com APPENDIX A STANDARD CALIBRATION A 2 TEMPERATURE CALIBRATION Use a Temperature Calibration Kit Available as an accessory If the analyzer has been recently used allow at least 30 minutes before performing calibration Use only the OHAUS Temperature Calibration Kit Using other methods could damage the Analyzer d G Remove pan and pan support Appears in software prior to 1 07 7 n u in uw a 2 z a ee Nu Beep amp Blink 7 7 Read Temp ts F Beep amp Blink thru Grating Match NIN Analyzer returns to Weigh mode AN Allow Temperature Calibration Unit to cool before removing it Ohaus Corporation www ohaus com 2 MB23 MB25 Service Manual APPENDIX A CALIBRATION A 3 SERVICE CALIBRATION Span calibration from the service menu allows you to set a new zero and maximum setting This is distinct from user level span calibration which allows a user to adjust the zero and maximum setting within the range established by the service menu span setting Remove any load from the Pan including sample pan Analyzer must be OFF but plugged in Have 100g and 50g calibration masses available Note To cancel calibration without saving changes press po Release keys Place weight on pan Clear pan 9 Place weight
40. termine if the unit meets specifications Turn the Moisture Analyzer on and allow it warm up for at least one hour before performing these tests NOTE N Make sure the test area is free from drafts and the surface the Analyzer rests on is level and vibration free An ASTM Class 1 or OIML Class E2 Tolerance mass should be used for the performance tests and adjustments 42 Operational Test Check the Analyzer s voltage rating and plug the Power Cord into a suitable power source 4 3 Segment Display Test Turn the Moisture Analyzer on and ensure that all segments are enabled and displayed briefly This is a Segment Display Test See Figure 4 1 LJ LU LJ LJ T g Figure 4 1 Segment Display 4 4 Performance Tests Accurate performance is determined by a series of three performance tests Precision Off Center Load and Centered Load The displayed readings are compared with the tolerances listed in Table 4 1 Before starting the performance tests level the Moisture Analyzer TABLE 4 1 TYPES OF PERFORMANCE TESTS amp TOLERANCES PERFORMANCE TEST Tolerance MB25 Tolerance MB23 T 0 296 3g sample 0 396 3g sample nl 0 05 10g sample 0 2 10g sample The following performance tests are used to evaluate the Moisture Analyzer operation before and after repairs Each Moisture Analyzer tested must meet the requirements specified in each test as well as the specifications listed in Table 1 1 A Moisture Anal
41. the cavity in the Chamber Top Figure 3 34 Removing screw to access Temperature Sensor Cable Remove the clip that secures the Heater See Figure 3 35 Remove the screws and washers that secure the Temperature Sensor See Figure 3 36 Lift out the Temperature Sensor Install the new Temperature Sensor and insert the screws and washers that secure it Figure 3 35 Removing clip that secures the Heater with needle nose pliers Thread the Temperature Sensor Cable around the plastic post on the side of the Chamber Top Housing as shown Insert the screw and washer Connect the Temperature Sensor Cable Replace the clip that secures the Heater the Reflector and the Chamber Top See Section 3 9 2 Reassemble the Heater Unit and Re install the Top Housing Perf T ture Calibration nm Figure 3 36 Removing screws and washers securing Temperature Sensor If Calibration is successful conduct Performance Tests See Chapter 4 Ohaus Corporation www ohaus com 3 14 MB23 and MB25 Service Manual CHAPTER 3 MAINTENANCE PROCEDURES 3 9 INSTALLING THE TOP HOUSING 1 Stand the Top Housing up at the back of the Bottom Housing so the cables from the heater unit can be plugged in See Figure 3 37 2 Insert the connectors for the Fan and Temperature Sensor on the left and the Thermal Overload Device and ground cable for the MB23 on the right as shown Figure 3 37 sehe cables to the Pow
42. uration is selected A N Short or long press Increases the value of the time setting Short or long press Decreases the value of the time setting Te Short press Accepts the blinking value and returns to Weigh mode Short press Exits Edit mode without saving changes Note After 5 seconds of no activity the blinking setting is automatically saved and the mode returns to Weigh mode Run Mode Performing a Test A moisture determination test is initiated The results in progress are displayed NOTE To setup a test 1 Place a container on the Pan and press Tare 2 Place mass to be tested gt 0 5g on Pan Then press Start as below Short press Activates Run mode initiates test with sample greater than 0 5g 9 Changes the unit of displayed result toggles between weight grams gt Moisture gt Solids Short press Stops test in progress s Sends current displayed value to the RS232 Result Mode At the end of the test Run Mode the display blinks the test result Changes the unit of displayed result weight grams gt Moisture gt 95 Solids Exits to Weigh mode Sends current displayed value to the RS232 Ohaus Corporation www ohaus com 1 6 MB23 and MB25 Service Manual CHAPTER 1 GETTING STARTED 1 5 4 Power Verify that the input voltage printed on the voltage identification label information and the plug type matches the location s AC power supply Connect the supplied
43. yzer which passes each of these three tests meets the manufacturing specifications MB23 and MB25 Service Manual 4 1 Ohaus Corporation www ohaus com CHAPTER 4 FINAL TESTING 4 4 1 Precision Test In Analyzer specifications the term Precision means the Standard Deviation of a set of similar weight readings To determine if an Analyzer meets the calculated Standard Deviation value in the Specification Table 4 1 perform the following test 1 Tare the Analyzer The reading on the display should be 0 0009 2 Place a 50g mass on the center of the sample pan Observe and record the reading when the stable indicator comes on 3 Remove the mass The reading should return to 0 000 within the published tolerance when the stable indicator is on 4 Repeat this test for ten readings Ifthe standard deviation of the readings is less than the indicated tolerance the Analyzer passes the Precision Test CAUTION Remove the mass from the pan after testing Adjustment If the deviation for any set of readings using the same mass placed on the center of the pan is greater than the indicated tolerance the Moisture Analyzer does not meet the Precision Test specification Inspect and correct the following areas 1 Check for mechanical obstructions any foreign object touching any part of the moving pan linkage assembly will cause the Analyzer to fail the Precision Test Inspect and correct as necessary 2 Anerror in the Off Center Load Test can
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