OHAUS T71P, Service Manual

Page: 37 / 48

CHAPTER 4 TESTING
4.1 TESTING
Before and after servicing the Indicator, operational and performance tests should be made to
determine if it meets specifications. Turn the Indicator ON and allow it to warm up for at least
ten minutes before performing these checks. The masses used for calibration should be
ASTM Class 4 or OIML Class F2 tolerance or better.
NOTE:
Make sure the test area is free from drafts and that the base rests on a level and
vibration-free surface. The masses used for final calibration must be adjusted to
ASTM Class 4 or OIML Class F2 tolerance or better.
4.2 Power Test
The purpose of this test is to determine if the electronic circuitry of the Indicator is functioning
properly or not at all. In some cases, the AC Adapter or line cord supplied with the Indicator may
have become defective.
1.
Plug the AC Adapter or line cord into a suitable power source.
2. With the Indicator connected to an appropriate power supply, press the ON/ZERO Off
button. The Indicator performs a self-test, indicates the software revision and then goes
into weighing mode.
3.
If all of the displays appear normal in this test, continue with the next test. If the display
did not appear, check that the AC input is good, and that the AC adapter or line cord are
functioning properly, and repeat the test. If the display was erratic, the PC board is
defective and requires replacement.
4.3 Performance Tests Using a Scale Base
These tests are performed on the Indicator using a known good scale base and test mass.
At this point, the Indicator has been checked for full display, menu setup and calibrated.
If a Load Cell Simulator is being used, proceed to paragraph 4.4.
Select the maximum possible resolution (<1:20,000) to obtain the most accurate test results.
7000 Series T71 Indicators Service Manual 4-1 Ohaus Corporation www.ohaus.com