Revision B
120 Series Maternal/Fetal Monitor
7-21
2015590-001
Calibration: Trimline Tocotransducer Calibration
10. Adjust the ZERO CTR and/or the ZERO TRIM potentiometer(s) so that the
voltage measured across TP6 and TP2 (or TP3) matches the reading recorded in
step 7, ± 0.04 V. This voltage is referred to as the WEIGHT ON voltage.
The ZERO CTR potentiometer provides course adjustment.
The ZERO TRIM potentiometer provides fine adjustment.
11. Remove the weight and observe the voltage reading; this voltage is referred to
as the WEIGHT OFF voltage. A correctly adjusted transducer will show a
voltage change of +0.637 V ± 0.04 V from the WEIGHT ON to WEIGHT OFF
voltage. If the change is less than 0.597 V, adjust the GAIN potentiometer
counterclockwise to increase the gain. If the change is more than 0.677 V, then
adjust the GAIN potentiometer clockwise to decrease the gain.
12. Repeat step 9 through step 11 until the change in voltage between the WEIGHT
ON and WEIGHT OFF conditions falls into specification.
13. Torque seal all potentiometers. Re-seal with waterproof sealing tape and re-
install the nameplate.
CAUTION
REPEAT MEASUREMENTS—Due to offset voltages induced by
the circuitry in the Trimline Tocotransducer, it is necessary to
adjust the change in voltage between the WEIGHT ON condition
and WEIGHT OFF condition—instead of simply adjusting the
output voltage for each condition. Adjusting the GAIN
potentiometer while monitoring the voltage at TP6 may show little
or no voltage change as the potentiometer is being adjusted.
However, when the weight is again placed on the button, the
output voltage for this condition may have changed significantly.
In summary, it is necessary to adjust the GAIN potentiometer and
then recheck the voltages during both the WEIGHT ON condition
and the WEIGHT OFF condition to determine the effectiveness of
the adjustment. As stated in step 12, the procedure is repeated
until the voltages fall into specification for both conditions.
Summary of Contents for Corometrics 126
Page 1: ...Corometrics 120 Series V3 5 SERVICE MANUAL MANUAL P N 2015590 001 REV B ...
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Page 409: ...Revision B 120 Series Maternal Fetal Monitor C 1 2015590 001 Appendix C Drawings C ...
Page 410: ...C 2 120 Series Maternal Fetal Monitor Revision B 2015590 001 Drawings For your notes ...
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