OHAUS SCOUT Service Manual

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OHAUS SCOUT Service Manual Manual pdf 27 page image

4-7CHAPTER 4 MAINTENANCE PROCEDURES4.2.3.1 Precision Test (Cont.)AdjustmentIf the deviation for any set of readings (using the same mass placed on the center ofthe Pan) is greater than +1 count, the balance does not meet the Precision Testspecification. Inspect and correct the following areas:1. Check for mechanical obstructions. Any foreign object touching any partof the moving Pan linkage assembly will cause a balance to fail thePrecision Test. Inspect and correct as necessary.2. An error in the Off-Center Load Test can affect the results of the PrecisionTest. Inspect and correct if necessary. See Off-Center Load Test.3. Foreign material or debris located in the balance between the Pan/Platformand the Base will cause the balance to fail the test.4. Environmental influences such as vibrations, drafts or a non-level surface cancause failures.4.2.3.2 Off-Center Load TestThe Off-Center Load Test is used to determine whether displayed weight values will beaffected by moving the sample to different areas of the Pan (6).Test1. Place 1/2 of the balance capacity in thecenter of the Pan (6).2. Press the ReZero On Switch to return the reading to zero.3. Move the mass halfway (between the center and the edge) to the front ofthe Pan (6). Note any differences in the displayed weight reading.4. Repeat this test for the back, left, and right positions.5. Maximum allowable change in displayed weight readings is + 1 count foreach of the four positions. If this reading is exceeded, it usually indicates adefective Transducer (8).4.2.3.3 Centered Load TestThis test is used to determine the linearity of the unit throughout its operating range.The masses used to perform this test must be adjusted to ASTM Class 4 Tolerance, orbetter.NOTE:The balance must pass the Off-Center LoadTest and Precision Test before the CenteredLoad Test may be performed.