R Ec Alibration - Time Electronics 1044 Manuel Technique

6. R ec alibration

Introduction
Recalibration of the 1044 is essential to ensure both correct operation and maintain
accuracy. Recalibration is recommended annually.
This chapter gives calibration information.
Recalibration
This instrument is calibrated before it leaves the factory and the calibration controls will not
normally need adjustment, although periodic annual re-calibration is recommended. If re-
calibration is found to be necessary then follow this calibration procedure and adjust the
outputs to the published specifications.
All readings are taken from the front panel LCD display. Once calibrated, the 1044 would
only need verification that these readings are accurate. Equipment required for verification is
a digital multimeter with accuracy of at least 0.01% and a voltage and current source of
similar accuracy. Suggested items would be the Time Electronics 5075 High Resolution
Digital Multimeter and the Time Electronics 5018 Voltage and Current calibrator.
The calibrator procedure is as follows -
To adjust the trim pots follow the procedure described in fuse replacement.
The zero is factory set and should not require adjustment. Set the Output Adjust
potentiometer to full scale. All adjustments are to be within 0.05% ± 1 count and are taken
from the front panel LCD display.
1) Locate the 200mV trimmer pot on the rear of the LCD display. This can be reached via a
hole in the PCB. Set the 1044 to the 200mV range and adjust the trimmer to give 200mV.
2) Locate VR7 - 20V adjust. Select the 20V range and adjust VR7 for reading of 20V.
3) Locate VR6 - 2V adjust. Select the 2V range and adjust VR6 for a reading of 2V.
4) Locate VR5 - 20mA adjust. Select the 20mA current range and adjust VR5 for a reading
of 20mA.
5) Locate VR4 - 2mA adjust. Select the 2mA current range and adjust VR4 for a reading of
2mA.
6) Locate VR3 - 200uA adjust. Select the 200uA current range and adjust VR3 for a reading
of 200uA.
Once these readings have been completed, verification that the LCD display is reading
correctly is necessary. This is performed by injecting a known 200mV signal into the 1044
whilst in measure mode and set to the 200mV range. If the reading is out of specification,
the unit is faulty and must be repaired.
V1.1 09/01/11
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