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CHAPTER 5 PARTS LISTS & DIAGRAMS

MB23 and MB25 Service Manual

5-3

Ohaus Corporation www.ohaus.com

5.1 MB23 & MB25: HOUSING & INTERNAL PARTS

TABLE 5-1. MB23 & MB25: HOUSING & INTERNAL PARTS

Drawing Item

Description

Top Housing Chamber

Reflector

Heater, MB23

Heater, MB25

Temperature Sensor

Heater Frame Housing

Thermal Overload Device (MB23)

Thermal Overload Device (MB25)

Protective Glass, MB25

Pan Handler

Pan Support

Draft Shield

Chamber Housing

Fan, with cables

Fan Plate

Top Housing

Leveling Bubble

Load Cell Cover

Load Cell

Power PCB

Bottom Housing

Hardware Kit

In-Use Cover

Function Label

Cable Set

LCD

Main PCB

AC Line Cord

Summary of Contents for MB25

Page 1: ...SERVICE MANUAL Ohaus Corporation 7 Campus Drive Suite 310 Parsippany NJ 07054 USA 973 377 9000...

Page 2: ......

Page 3: ...cation 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 8025...

Page 4: ......

Page 5: ...p Housing Components 3 4 3 3 1 Test the Heater Circuit 3 4 3 3 2 Test the Temperature Sensor and Cable 3 4 3 3 3 Test the Fan 3 4 3 3 4 Test the Ground Circuit on the MB23 3 4 3 4 Testing the Power PC...

Page 6: ...LUSTRATIONS FIGURE NO TITLE 1 1 MB23 and MB25 Function Labels 1 4 1 2 MB23 MB25 Display Indicators 1 4 1 3 AC Power 1 7 1 4 RS232 DB9 pin setup 1 8 1 5 Solder Points on PCB 1 8 3 1 MB25 with Top Open...

Page 7: ...2 3 29 MB 25 Thermal Overload Device Installed 3 12 3 30 Screws in Fan Plate 3 13 3 31 Grommets Slide Out from the Bottom Plate 3 13 3 32 Lid Position Rod and Spring under the Fan Plate 3 13 3 33 Remo...

Page 8: ...TABLE OF CONTENTS MB23 and MB25 Service Manual iv Ohaus Corporation www ohaus com...

Page 9: ...ntains 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 An...

Page 10: ...10 megohms in 1 Volt dc position 2 Standard electronics tool kit 3 Soldering iron 50 watt and solder rosin core solder not acid core 4 Solder remover 5 Ohaus Temperature Calibration Kit P N 11113857...

Page 11: ...ter Load cap dist 5d Tare range To capacity by subtraction Stabilization Time 3 seconds Calibration Weight External Calibration Mass 50g Calibration Temperature OHAUS Temperature Calibration Kit Tempe...

Page 12: ...ck short press Set Increase value short or long press Tare Tare short press Enter Accept value short press Set Decrease value short or long press Temp Temperature Setting short press Print Cal Print s...

Page 13: ...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 th...

Page 14: ...eigh 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...

Page 15: ...connection Intentionally disabling the equipment grounding connection is prohibited Disconnect the Analyzer from the power supply when cleaning 1 5 5 Power On Off On short press Off Standby Mode long...

Page 16: ...r Remote Print operation HAND SHAKE CTS RTS In Out 5 9 1 6 DATA RxD TxD In Out GND Remote Tare Remote Print Solder Bridge Solder Bridge 1 2 3 4 5 6 7 8 9 10 11 12 CN1 Gnd BD1 VCC ShDn RTS TxD RxD CTS...

Page 17: ...able 2 2 to locate the symptom Follow the suggested remedies in the order they appear 5 Visual Check Examine the Load Cell for signs of bending twisting or corrosion Clean the unit before evaluating a...

Page 18: ...install Pan Support Perform troubleshooting steps Section 2 1 Clean the unit thoroughly Err 8 5 Analyzer temperature is higher than 50 C Cool down the analyzer Err 8 6 1 Analyzer temperature is higher...

Page 19: ...p Defective display Defective Main PCB Replace Display LCD Replace Main PCB Cannot calibrate Unstable environment Incorrect calibration masses Move unit to suitable location Use correct calibration ma...

Page 20: ...r 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 DO NOT USE CHEMICAL CLEANERS OR SOLVENTS OF ANY TYPE SOME CL...

Page 21: ...3 1 3 Pull away the Housing Chamber Figure 3 2 Housing Chamber Figure 3 1 MB25 with top open 4 Lift out the plug in the Housing 5 Remove the clear plastic In use Cover that protects the Function Label...

Page 22: ...e Top Housing so the rear stays in place and the front rises See Figure 3 6 Figure 3 6 Lifting the Housing 8 Remove the three cables connected to the Power PCB Figure 3 7 9 On the MB23 disconnect the...

Page 23: ...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...

Page 24: ...sition Rod between D and E Reading should CN1 CN2 CN3 CN4 CN6 CN5 FU1 FU2 Pin 20 Pin 1 Pin 2 Pin 19 D E LID POSITION SENSOR Figure 3 9 Power PCB connectors be approx 3 vdc 6 Jump pins 13 to 18 Measure...

Page 25: ...nnect 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 Reassemble the Moisture Analyzer 1...

Page 26: ...old 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 6 Lift out the Load Cell Figure 3 14 Load Cell 7 Disconnect t...

Page 27: ...arating 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...

Page 28: ...nd washers that secure the Heater 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 Figure 3 21 Connec...

Page 29: ...ntly lift the Heater up and out Figure 3 24 3 8 4 Replacing the Heater on the MB25 1 Grasp the new Heater by its base gently press it against the retainer clips opposite and press it down until it cli...

Page 30: ...tests are OK reassemble the Top Housing See Section 3 8 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...

Page 31: ...ts bolt through the hole in the base of its blade See Figure 3 27 4 Fit the washer and then the nut and use a wrench to tighten the nut Figure 3 27 MB25 Thermal Overload Device 5 MB23 Mount the ground...

Page 32: ...ht 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 h...

Page 33: ...Sensor See Figure 3 36 6 Lift out the Temperature Sensor 7 Install the new Temperature Sensor and insert the screws and washers that secure it Figure 3 35 Removing clip that secures the Heater with ne...

Page 34: ...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 t...

Page 35: ...USING continued 10 Place the clear plastic In use Cover on top of the Function Label 11 Push in the Housing Chamber Figure 3 41 Housing Chamber Figure 3 40 Clear plastic In use Cover 12 Install the Pa...

Page 36: ...ensure that all segments are enabled and displayed briefly This is a Segment Display Test See Figure 4 1 Figure 4 1 Segment Display 4 4 Performance Tests Accurate performance is determined by a series...

Page 37: ...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 rea...

Page 38: ...ly 50 grams place the sample on the center of platform Record the reading on the worksheet provided 3 Remove the sample from the platform 4 Repeat this test starting at Step 1 until you record a total...

Page 39: ...nge 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...

Page 40: ...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 thi...

Page 41: ...aus Corporation www ohaus com 5 2 MB23 and MB25 Service Manual 5 1 MB23 MB25 HOUSING INTERNAL PARTS MB23 MB25 26 70 20 1 2 4 6a 3a 8 7 10 11 12 13 21 22 14 16 18 19 17 24 25 5 9 23 15 3b 6b Figure 5 1...

Page 42: ...r MB23 3b Heater MB25 4 Temperature Sensor 5 Heater Frame Housing 6a Thermal Overload Device MB23 6b Thermal Overload Device MB25 7 Protective Glass MB25 8 Pan Handler 9 Pan Support 10 Draft Shield 11...

Page 43: ...CHAPTER 5 PARTS LISTS DIAGRAMS Ohaus Corporation www ohaus com 5 4 MB23 and MB25 Service Manual...

Page 44: ...r 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...

Page 45: ...minutes before performing calibration Use only the OHAUS Temperature Calibration Kit Using other methods could damage the Analyzer 1 Remove pan and pan support Appears in software prior to 1 07 0 000...

Page 46: ...ange 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 ca...

Page 47: ...APPENDIX A STANDARD CALIBRATION Ohaus Corporation www ohaus com A 4 MB23 and MB25 Service Manual...

Page 48: ...st software service tool version and instructions on how to use it please follow below steps 1 Go to http dmx ohaus com and log in with your username and password 2 Go to View by product 3 Open the fo...

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