SECTION IV - MAINTENANCE
A. ELECTRICAL MAINTENANCE
1. CALIBRATION
The Autograf Model 2s as shipped is standardized against a Weston Standard
Cell. Based upon expected shelf life of the Mercury cell, the calibration
should accumulate error at the rate of about 0.2570 every six months. The
Mercury reference cell may be considered at the end of its useful life'in ap-
proximately 18 months.
If necessary, the instrument may be recalibrated as follows:
a. For maximum accuracy (0. 1% or better):
1. Move the Power and Servo switches to the "ONtt ,psition and allow
the various components of the instrument to reach a stabilizing
temperature.
2. Move the Record-Follow switch to the Record position and adjust
the Zero setting controls to bring the pen and carriage indices
into exact agreement with the "10" mark on the X and Y scales.
3. Set the X and Y Scale Ranges to the 1. 5 and 1 volt positions respec-
tively, and the "fixed-var" switch to ftfixedtl.
4. Connect an accurately established 1 volt source (as obtained, for
example from an L & N precision potentiometer and Weston Standard
Cell) with reversed ,polarity to the recorder input terminals. Con-
nected in this manner, the source voltage will drive the pen and car-
riage close to the lower left-hand corner of the paper.
5. Adjust the standardizing rheostats R- 1 1 (mounted on the input plug
panel, near the terminals) to bring the pen and carriage indices
into exact agreement with the ttO" mark on the X and Y scales. Re-
move input and check to see if pen and carriage move back to initial
position. Repeat adjustment if necessary.
b. For moderate accuracy (0.25%)
Follow steps 1, 2, and 3, as above. Connect a Weston or other Standard
Cell to the recorder input terminals with reversed polarity, using an
appropriate, accurate, series resistor to establish a 1 volt source.
Proceed as in step 5 of (a).
26 |
ACEC
HEWLETT-PACKARD
