Revision C 170 Series Monitor 7-29
2000947-004
Serviceable Assemblies: Tocotransducer Calibration
4. Connect the positive lead of the digital voltmeter to TP2; connect the negative
lead to TP9.
5. Apply power to the 170 Series Monitor; then plug the CMR Test Jack into the
monitor’s front panel uterine activity connector.
6. Measure the voltage at TP2 and record the value.
7. Replace the CMR Test Jack with the tocotransducer to be calibrated.
8. Place the tocotransducer on a flat surface so that the button is face up, then
center the 52.5 gram weight on the button.
9. Adjust the ZERO TRIM potentiometer so that the voltage measured across TP2
and TP9 matches the reading recorded in step 6, ± 0.005 V. This voltage is
referred to as the WEIGHT ON voltage.
NOTE: If the ZERO TRIM potentiometer does not provide enough adjustment,
center the ZERO TRIM potentiometer and adjust the ZERO CENTER
potentiometer to match the reading recorded in step 6, ± 1.0 V. then use the
ZERO TRIM potentiometer to match step 6, ± 0.005 mV.
10. 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 +0.142 V ± 0.015 V from the WEIGHT ON to WEIGHT
OFF voltage. Use the GAIN potentiometer to adjust the GAIN the gain.
11. Repeat step 8 to step 10 until the change in voltage between the WEIGHT ON
and WEIGHT OFF conditions falls into specification.
12. Torque seal all potentiometers. Affix new sealing tape and re-install the
nameplate.
13. Refer to “Testing a Repaired Transducer (TOCO or US)” on
page 7-34.
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