OHAUS MB120 User manual

SERVICE MANUAL
MB90 & MB120
Moisture Analyzer

TABLE OF CONTENTS
MB90 MB120 Series Service Manual i Ohaus Corporation www.ohaus.com
Page No.
CHAPTER 1 - GETTING STARTED .......................................................................................... 1
1.1 Introduction.................................................................................................................. 1
1.2 Definition of Signal Warnings and Symbols.................................................................. 2
1.3 Safety Precautions....................................................................................................... 2
1.4 Service Facilities.......................................................................................................... 3
1.5 Tools and test equipment required............................................................................... 4
1.6 Test mass required ...................................................................................................... 4
1.7 Specifications............................................................................................................... 5
1.7.1 Admissible Ambient Conditions: Use only in closed rooms................................. 5
1.8 Controls ....................................................................................................................... 7
1.8.1 Display............................................................................................................... 8
1.9 Setup navigation .......................................................................................................... 9
1.9.1 Setup screen...................................................................................................... 9
1.9.2 Weight and temperature calibration.................................................................... 9
1.9.3 User settings.....................................................................................................14
1.9.4 Device settings..................................................................................................17
1.9.5 Peripherals........................................................................................................19
1.9.6 Print ..................................................................................................................21
1.9.7 Company information.........................................................................................22
1.9.8 User management.............................................................................................23
1.10 System and data management..................................................................................25
CHAPTER 2 – TROUBLE SHOOTING .....................................................................................27
2.1 Trouble shooting .........................................................................................................27
2.1.1 General Procedures for Troubleshooting...........................................................27
2.2 Problem solver............................................................................................................28
2.3 Testing........................................................................................................................29

TABLE OF CONTENTS
MB90 MB120 Series Service Manual ii Ohaus Corporation www.ohaus.com
2.3.1 Operational Test ...............................................................................................29
CHAPTER 3 – MAINTENANCE PROCEDURES ......................................................................30
3.1 Preventive maintenance..............................................................................................30
3.1.1 Preventive Maintenance Checklist ....................................................................30
3.2 Preventive measures ..................................................................................................30
3.3 Opening the MB90 and MB120...................................................................................32
3.4 Replacing the power PCB and power switch..............................................................34
3.5 Replacing the AC plug fuse.........................................................................................36
3.6 Replacing the AC plug ................................................................................................36
3.7 Replacing the control board ........................................................................................37
3.8 Replacing the main PCB.............................................................................................38
3.9 Replacing the load cell................................................................................................39
3.10 Replacing the load cell accessory kit.........................................................................40
3.11 Replacing the heating chamber parts........................................................................42
3.11.1 Opening the Heating Chamber Compartment. ................................................42
3.11.2 Replacing Top Housing Components..............................................................50
CHAPTER 4 – FINAL TESTING ...............................................................................................54
4.1 Final tesing..................................................................................................................54
4.2 Operational Test .........................................................................................................54
4.3 LCD Display Test........................................................................................................54
4.4 Performance Tests......................................................................................................54
4.4.1 Precision Test...................................................................................................55
4.4.2 Repeatability Test ............................................................................................56
4.4.3 Repeatability Test .............................................................................................57
4.4.4 Linearity Test ....................................................................................................57
CHAPTER 5 PARTS IDENTIFICATION & DIAGRAMS.............................................................59
5.1 MB90 & MB120 parts............................................................................................59

TABLE OF CONTENTS
MB90 MB120 Series Service Manual iii Ohaus Corporation www.ohaus.com
APPENDIX A. Weight and temperature calibration ..................................................................61
A.1 Weight Calibration .......................................................................................................61
A.2 Temperature Calibration..............................................................................................64
APPENDIX B. SOFTWARE SERVICE TOOL INSTRUCTIONS...............................................67
B.1 Restore EEPROM........................................................................................................69
B.2 Replace Main PCB. .....................................................................................................71
B.3 Replace Control Board. ...............................................................................................74
B.4 Diagnostics..................................................................................................................77
B.4.1 Ramp ON ..........................................................................................................78
B.4.2 Linearization (Service Linearization Calibration)................................................79
B.4.3 Span (Service Span Calibration)........................................................................80
APPENDIX C. DOWNLOADING ANALYZER FIRMWARE ......................................................81
C1. MB90_MB120 Firmware..............................................................................................81
C2. Downloading MB90 and MB120 Firmware..................................................................81
C2.1 software version SR1.03 or before .....................................................................81
C2.2 software version SR1.10 or later.........................................................................83
C3. Clear software.............................................................................................................85
C4. Reset the Analyzer Password......................................................................................87

CHAPTER 1 - GETTING STARTED
MB90 MB120 Series Service Manual 1 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 Ohaus MB90&MB120 Moisture Analyzer. Familiarity with the scale’s Instruction
Manual is assumed. The contents of this manual are summarized below:
Chapter 1 Getting Started – Contains information on service facilities, tools and test
equipment, specifications, and the control functions of the scale.
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 Final Testing – Contains a list of required test masses, an operational test,
segment display test, performance tests and adjustments.
Chapter 5 Parts Identification and Diagrams – Contains exploded views of Ranger scales
identifying all serviceable components.
Appendix A Standard Calibration – Explains procedures for Temperature and Weight
Calibration, performed prior to using a scale, and after service.
Appendix B Software Service Tool – Explains how to use the software tool when a new Main
PCB is installed to Configure the Main PCB, enter balance serial number, and install software.
Appendix C Downloading analyzer firmware– Explains how to download and install the
software.

CHAPTER 1 - GETTING STARTED
MB90 MB120 Series Service Manual 2 Ohaus Corporation www.ohaus.com
1.2 Definition of Signal Warnings and Symbols.
Safety notes are marked with signal words and warning symbols. These show safety issues and
warnings. Ignoring the safety notes may lead to personal injury, damage to the instrument,
malfunctions and false results.
Signal Words
WARNING for a hazardous situation with medium risk, possibly resulting in severe injuries or
death if not avoided.
CAUTION for a hazardous situation with low risk, resulting in damage to the device or the
property or in loss of data, or minor or medium injuries if not avoided.
Attention (no symbol)
for important information about the product.
Note (no symbol)
for useful information about the product.
Warning Symbols
General Hazard Electrostatic discharge sensitive
Electric Shock Hazard Hot surface
1.3 Safety Precautions
•AC mains powered:
- Verify that the local AC power supply is within the input voltage range printed on the
equipment’s data label. - Only connect the AC power cord to a compatible grounded
electrical outlet.
•Do not position the analyzer such that it is difficult to disconnect the power cord from the
power receptacle.

CHAPTER 1 - GETTING STARTED
MB90 MB120 Series Service Manual 3 Ohaus Corporation www.ohaus.com
•This equipment is intended for indoor use and should only be operated in dry locations.
•Allow sufficient space between analyzer and other equipment for better air ventilations.
•Operate the equipment only under ambient conditions specified in the user instructions.
•Do not operate the equipment in hazardous or unstable environments.
•Disconnect power from the equipment before cleaning or servicing the equipment.
•Always allow the unit to have sufficient time to cool down after every heating (minimum
30 minutes).
•Service should only be performed by authorized personnel.
•Use electrostatic protection measures when handling the printed circuit board.
•Only use original replacement parts and accessories.
1.4 Service Facilities
To service a moisture analyzer, the service area should meet the following requirements:
•Should be temperature controlled and meet scale 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.
•Area must be clean and free of excessive dust.
•Work surface must be stable and level.
•Scale must not be exposed to direct sunlight or radiating heat sources.
•Use an approved Electro-Static Device.

CHAPTER 1 - GETTING STARTED
MB90 MB120 Series Service Manual 4 Ohaus Corporation www.ohaus.com
1.5 Tools and test equipment required
The service shop should contain the following equipment:
1. Standard hand tools.
2. Digital Voltmeter (DVM): input impedance of min. 10 megohms in 1 Volt dc position.
3. Standard Electronics tool kit.
4. Soldering iron (50 watt) and solder (rosin core solder, not acid core).
5. Solder remover.
6. Ohaus Temperature Calibration Kit P/N 11113857
7. Soft, lint-free cleaning cloth
8. Anti-static bags for PCBs
9. Anti-static wrist strap and mat
1.6 Test mass required
Use a 50 gram test mass with ASTM Class 1 or OIML Class E2 Tolerance.