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.

CHAPTER 1 - GETTING STARTED
MB90 MB120 Series Service Manual 5 Ohaus Corporation www.ohaus.com
1.7 Specifications
TABLE 1-1. SPECIFICATIONS
Model
MB120
MB90
Capacity
120g
90g
Readability
0.001g, 0.01%
Repeatability (Std Dev) (g)
3g sample 0.05%
3g sample 0.18%
10g sample 0.015%
10g sample 0.05%
Repeatability (by Std. Dev.)
(d)
1.5d
Linearity (d)
5d
Off Center Load (½ cap, ½
dist)
4d
Results
Moisture %, Solids %, Regain %, Wt (g), Wt
(custom)
Temperature Range
40
℃
-230
℃
40
℃
-200
℃
Drying Programs
Standard, Fast, Ramp,
Step
Standard and Fast
Switch-off Criteria
Timed, Auto (30, 60, 90
seconds), Autofree
mg/s, Autofree %/s,
manual
Manual, Time and Auto
Heat Source
Halogen
Display Results
% moisture,%
solids,%Regain,
weight(g),temperature,
time, test ID, drying
curve
% moisture, % solids,
weight(g), temperature
and time
Calibration
External calibration mass – 50g
Dimensions (WxHxD) (in/cm)
21x18x35
Pan Size
90mm diameter
Adjustable Feet and Level
Yes
Interface
RS232, USB host, USB device
Weight (lb/kg)
5.23
Shipping Weight (lb/kg)
8.35
1.7.1 Admissible Ambient Conditions: Use only in closed rooms
Indoor use only.

CHAPTER 1 - GETTING STARTED
MB90 MB120 Series Service Manual 6 Ohaus Corporation www.ohaus.com
Altitude
Up to 4000m
Temperature range
5 ºC to 40 ºC
Atmospheric humidity
Maximum relative humidity 80% for temperatures up to
31 °C decreasing linearly to 50% relative humidity at 40 °C.
Warm-up time
At least 60 minutes after connecting the instrument to the
power supply; when switched on from standby-mode, the
instrument is ready for operation immediately.
Voltage fluctuations
Mains supply voltage fluctuations up to –15% +10% of the
nominal range
Over voltage category
II
Pollution degree
2
Power load
Max. 450 W during drying process
Current consumption
5 A or 2.5 A, according to the heating element
Power supply voltage
100 V – 120 V or 200 V – 240 V, 50/60 Hz (the voltage is
given by the heating element)
Power line fuse
1 piece, 5 x 20 mm, T6,3 H 250 V

CHAPTER 1 - GETTING STARTED
MB90 MB120 Series Service Manual 7 Ohaus Corporation www.ohaus.com
1.8 Controls
Figure 1-1. MB90 & MB120 Membrane Switch and Display.
1 Turns On or Off display and fan.
2 When pressed, sends Print command.
3 When pressed, either starts or stops the drying process.
4 When pressed, performs Tare function.
5 Leveling indicator
6
Leveling Feet
Used to level the Moisture Analyzer.
1
2
3
4
5
1
2
3
4
5
6

CHAPTER 1 - GETTING STARTED
MB90 MB120 Series Service Manual 8 Ohaus Corporation www.ohaus.com
1.8.1 Display
The display screen is divided into sections:
1 2 3 4
1. Test library: Change parameters and create new method.
2. Test results: Manage test results.
3. Setup: Change system settings.
4. Help guide: Method development guide and help information.
1 2 3 4
Figure 1-2. MB120 and MB90 Display Screen.
Button segment
Parameters segment
Results segment
Instruction segment
User name, date and time segment
Button segment
Parameters segment
Results segment
Instruction segment
Date and time segment

CHAPTER 1 - GETTING STARTED
MB90 MB120 Series Service Manual 9 Ohaus Corporation www.ohaus.com
1.9 Setup navigation
Press the SETUP to gain access into Setup Options.
1.9.1 Setup screen
The setup menu is activated by pressing the Setup button. The menu contains: weight and
temperature calibration, user settings, device settings, user management and system and
data management.
Figure 1-3. Setup Screen.
1.9.2 Weight and temperature calibration
1.9.2.1 Weight calibration
The Moisture Analyzer can be calibrated with an external mass of 50 grams. Calibration of the
Moisture Analyzer is not absolutely necessary for a correct moisture determination as the
measurement is relative. The balance determines the weight of the sample before and after
drying and the moisture is calculated on the basis of the ratio between wet and dry weights.
Nevertheless, you should calibrate the built-in balance under the following conditions:
- If this is stipulated by your quality assurance system (GLP, GMP, ISO 9001).
- If you suspect the analyzer has been abused.
To calibrate the analyzer, processed as follows:
Press Setup button on the main
screen.

CHAPTER 1 - GETTING STARTED
MB90 MB120 Series Service Manual 10 Ohaus Corporation www.ohaus.com
The Setup menu appears.
Press the Weight and temperature
calibration button.
The Adjustments screen appears.
Press the Weight adjustment-
external button
The display highlights the action you
should take.
Remove the sample pan and place the
required weight on the sample pan,
close the cover.
Follow the instructions on the display.
The display indicated if the calibration
was successful.

CHAPTER 1 - GETTING STARTED
MB90 MB120 Series Service Manual 11 Ohaus Corporation www.ohaus.com
1.9.2.2 Temperature calibration
You must have a temperature calibration kit to perform this procedure. If the Moisture Analyzer
has been recently used, allow at least 30 minutes before performing calibration.
Note: The temperature calibration kit is available as optional equipment.
Press Setup button on the main
screen.
Press Weight and temperature
calibration button.
Press Temperature calibration
button.
You are now prompted to remove
the pan handler and pan support.
Replace the pan handler and place
a temperature calibration unit on
the pan handler.
Note: The unit will not calibrate with the pan support in place.

CHAPTER 1 - GETTING STARTED
MB90 MB120 Series Service Manual 12 Ohaus Corporation www.ohaus.com
Press the Next and Start button to
initiate the temperature calibration
process. Follow the screen
prompts throughout the process.
The dryer unit is heated to a temperature of
100°C. You can observe the progress on the
display as the dryer temperature and count
down period are displayed. After 15 minutes,
read the thermometer through the inspection
window on the cover and enter this
temperature. Using the up/down arrow
buttons, adjust the display reading to agree
with the thermometer. Use the left/right arrow
buttons to highlight ACCEPT NEW CAL then
press the Enter button. You have 10 minutes
to make this adjustment, otherwise the
calibration is terminated.
This is a two-point adjustment (100°C and
160°C). The dryer unit now heats to the
second temperature (160°C). Adjustment of
the temperature is defined by two points.
Proceed exactly as you did for the first
temperature. After you have set the display
to agree with the thermometer, highlight
ACCEPT NEW CAL, then press the Enter
button. The display returns to ANALYZER
SETUP.

CHAPTER 1 - GETTING STARTED
MB90 MB120 Series Service Manual 13 Ohaus Corporation www.ohaus.com
1.9.2.3 Last temperature calibration result
Press Setup button on the main
screen.
The Setup menu appears.
Press Weight and temperature
calibration button.
The Adjustments screen appears.
Press the Last temperature
calibration result button.
Here you will find the last
temperature calibration result.

CHAPTER 1 - GETTING STARTED
MB90 MB120 Series Service Manual 14 Ohaus Corporation www.ohaus.com
1.9.3 User settings
1.9.3.1 Language
For convienence, the Moisture Analyzer is equipped with thirteen languages available on all
displays. This procedure permits the selection of any language.
Press Setup button on the main
screen.
The Setup menu appears.
Press User settings.
The User settings screen
appears.
Press Language button.
Select LANGUAGE.
Note: If you select English (US) as the dialog language, the date format is
changed and appears on all records in the American notation (month/day/year).