OHAUS MB120 Service Manual page 4

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
MB90 MB120 Series Service Manual
TABLE OF CONTENTS
ii Ohaus Corporation www.ohaus.com