Section 7
7-20
6. If necessary, adjust potentiometer R311 on the Servo-loop PCB until
the "Calibration" reading is between +2046 and +2047. Adjust
R311 until both numbers appear 50% of the time.
7. Disable the voltage standard's output, set the standard for -9.9976 V
and re-enable the standard's output.
8. If necessary, adjust potentiometer R312 on the Servo-loop PCB until
the "Calibration" reading is between -2047 and -2048. Adjust R312
until both numbers appear 50% of the time.
9. Disable the voltage standard's output.
10. The "Calibration" reading should be 0 ± 1 count.
11. Disconnect the voltage standard from the Servo-loop PCB.
b) Tracking Calibration
1. Leave the 10 , 0.01% GR resistors and the links connected to the
Rs and Rx test set front panel terminals.
2. Press the
<PREVIOUS> key until the "Monitor/Dacs/Turns/More
1-4" menu is displayed.
3. Using a long-range DMM, monitor the DC voltage at TP202 with
respect to TP302.
4. Set the current to 9.9976 mA and the number of turns to 8747.
5. Note the voltage at TP202 with respect to TP302.
6. Reverse the current polarity and again note the voltage at TP202
with respect to TP302.
7. If necessary, adjust potentiometer R313 on the Servo-loop PCB until
the voltage for POSITIVE polarity is the same as the voltage for
NEGATIVE polarity. The magnitude of the voltage should be 1.5
V.
8. Set the current polarity to POSITIVE.
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