CHAPTER 3 – MAINTENANCE PROCEDURES
MB90 MB120 Series Service Manual
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Ohaus Corporation www.ohaus.com
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.
– Do not 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 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 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
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 Preventive measures
Common hand tools are sufficient to disassemble the MB90 and MB120 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!
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 drifts more and the display can fluctuate
similar to when there is a draft.
