4-2
CHAPTER 4 TESTING
4.2 PERFORMANCE TESTS ALL BALANCES
Accurate performance of the Explorer balance is determined by a series of four performance tests. The displayed readings
are compared with the tolerances listed in Table 4-1. Tolerance values are expressed in counts. A one count change is
equal to the last digit shown on the balance display.
TABLE 4-1. TYPES OF PERFORMANCE TESTS
PERFORMANCE TEST ANALYTICAL
TOP LOADER TOLERANCE
TOLERANCE
210, 410/100, 610, 4100, 6100, 8100 12000, 22000, 32000
2100, 4100/1000
Repeatability
+ 1 Count
+ 1 Count
+ 1 Count
+ 1 Count
Off Center Load
+ 3 Counts
+ 2 Counts
+ 1 Count
+ 2 Counts
Linearity
+ 2 Counts
+ 2 Counts
+ 1 Count
+ 4 Counts
The following performance tests are used to evaluate the balance operation before and after repairs. Each balance tested
must meet the requirements specified in each test as well as the specifications listed in Table 1-2 depending upon the model.
Before proceeding with the following tests, all the procedures starting with paragraph 4.1 must have been accomplished on
the Balance first.
4.2.1Precision/Repeatability Test
Precision is a term used in balance specifications which means the standard deviation of a set of similar weight readings.
To conduct a Repeatability Test, proceed as follows:
1.With the balance calibrated, place a mass on the Pan equal to the capacity of the balance. Record the reading.
2.Remove the mass from the Pan, the balance should return to 0g. Record the reading.
3.Repeat steps 1 and 2 ten more times. Subtract the lowest from the highest reading to determine the differ-
ence. Maximum allowable difference is as listed in Table 4-1.
4.If the balance does not meet specifications, refer to Table 2-1 to determine the problem.
4.2.2 Off-Center Load Test
The Off-Center Load Test is used to determine whether displayed weight values will be affected by moving the sample to
different areas of the Pan.
Test for Analytical Balances
Place 1/2 of the balance capacity in the center of the Pan (1). Press the >O/T< button to return the reading to zero. Move
the mass halfway (between the center and the edge) to the front of the Pan. Note any differences in the displayed weight
reading. Repeat this test for the back, left, and right positions. Maximum allowable change is per Table 4-3 for each of the
listed balances four positions. To correct an off-center load error, proceed as follows:
Adjustment for Analytical Balances
This adjustment requires that the balance be partially disassembled to gain access to the Load Cell for adjustments. Refer
to Figures 5-2 and 5-3 in Chapter 5 for location of components called out in this procedure. Cable extenders are required
for the Main PC Board which must be operational for Load Cell adjustments.
See Figure 5-2 for steps 1 through 4.
1.With the balance turned OFF and unplugged, open the Draft Shield door and remove the Pan (5).
2.Remove Cover Plate (6).
3.Inside of the Draft shield, remove two Screws (2) and Lockswitch Cover Seal (1).
4.Carefully lift the Draft Shield from the balance Base and set aside.
Summary of Contents for EXPLORER
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Page 62: ...4 10 CHAPTER 4 TESTING ...
Page 88: ...5 26 CHAPTER 5 DRAWINGS AND PARTS LISTS ...
Page 106: ...APPENDIX B EXPLORER PRO EP LOADER B 10 ...
Page 112: ...APPENDIX D REPLACING BOTTOM DISPLAY BOARD D 4 ...
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Page 114: ...PN 80250985 SERVICE MANUAL EXPLORER EXPLORER PRO AND VOYAGER BALANCES 80250985 ...