18
Defender
™ Series Bases Service Manual
4.4
Consistency Check
To check the system prior to installation, make the following measurements. (Also make these checks if the
Indicator will not calibrate, or if the Indicator does not read correctly, or is giving unstable readings.)
1. Using a voltmeter, measure and record the excitation voltage supplied by the Indicator. Most
Ohaus indicators supply 5 volts dc for the excitation voltage.
2. Using an mV meter, measure and record the signal voltage with no load on the base.
CAUTION:
IN THE NEXT STEP, DO NOT OVERLOAD THE BASE BEYOND FULL CAPACITY RATING.
3. Using an mV meter, measure and record the signal voltage.
4. Obtain the mV/V output figure from the Load Cell data supplied with the Load Cell, and
compare the signal changes seen with the theoretical values from the Load Cell data. (See
Table 4-2.)
TABLE 4-2. LOAD CELL OUTPUT READINGS
(in mV with 5V Excitation)
Zero Load
50% Load
100% Load
±
0.1mv
4-6mv
9-11mv
4.5
Performance Tests
Accurate performance of the Defender series Bases is determined by two performance tests. The displayed
readings are compared with the tolerances listed in Table 1-1.
NOTE:
The following performance tests are used to evaluate base operation before and after repairs.
The base must meet the requirements specified in each test as well as the specifications listed
in Table 1-2. Before proceeding with the following tests, the base should be attached to an
indicator and calibrated.
(See Section 4.3.)
