CHAPTER 4 TESTING4.1 TESTINGAfter servicing the balance, an operational test and various performance tests should be madeto confirm that the balance meets specifications. Turn the balance on and allow it to warm upfor at least one hour before performing these tests.NOTE:Make sure the test area is free from drafts and that the balance rests on a level andvibration-free surface. The masses used for final calibration must be adjusted to ASTMClass 1 or OIML Class E1 tolerance or better.4.1.1 Operational Test1. Connect a functioning AC Adapter to the balance Power Jack located at the rear ofthe balance.2. Plug the AC Adapter into a suitable power source. If the AC Adapter supplied withthe balance is rated for a different voltage, use an appropriate adapter to match thesupply voltage.4.1.2 Models Segment Display Test1. Turn the balance on by pressing ON/ZERO Off, all segments are enabledand displayed briefly, then followed by a software revision number.See Figure 4-1 for full display.Figure 4-1. LCD Full Display for Discovery Balance.2. Tare the balance. The display should indicate a zero weight.4.2 Load Cell Performance Tests4.2.1 Off-Center Load TestThe Off-Center Load Test is used to determine whether displayed weight valuesare affected by moving the sample to different areas of the Pan.1. Place half of the balance capacity in the center of the Pan.2. Note the reading.3. Move the mass halfway (between the center and the edge) to the front of the Pan.Note any differences in the displayed weight reading.4. Repeat the test for the back, left, and right position of the Pan.Discovery Balance Service Manual 4-1 Ohaus Corporation www.ohaus.com
