Revision B 120 Series Maternal/Fetal Monitor 7-25
2015590-001
Calibration: Nautilus Tocotransducer Calibration
Calibration Procedure
Disassembly
CAUTION
HANDLING—Take care not to damage the transducer base
sealing groove.
1. Turn off the monitor.
2. Unplug the transducer from the monitor.
3. Use the screw cap extraction tool to pry off the five screw caps (Figure 7-6).
Discard all caps.
4. Remove the five sealing screws and discard.
5. Remove the transducer cover and flat-seal o-ring. Discard both items.
Calibration for Cat. No. (REF) 2264 GAX/HAX/JAX/KAX/LAX/MAX
1. Set the Gain (R11) and Offset (R6) potentiometers fully clockwise.
2. Connect the positive lead of the digital voltmeter to TP6 on the FECG/UA
board; connect the negative lead to TP2 or TP3.
3. Turn on the monitor.
4. Plug the CMR Test Jack into the monitor’s
UA connector.
5. Measure the voltage across the test points and record the value.
6. Replace the CMR Test Jack with the transducer to be calibrated.
7. Place the tocotransducer on a flat surface so that the button is face up, then
center the 52.5 gram weight on the pressure sensitive button.
8. Adjust the Offset (R6) potentiometer so that the voltage matches the reading
recorded in 5 ± 0.04 V. This voltage is referred to as the “weight on” voltage.
9. 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. If the change is less, adjust the Gain (R11)
potentiometer counterclockwise to increase the gain. If the change is more,
adjust the Gain (R11) potentiometer clockwise to decrease the gain.
10. Repeat 7 through 9 until the change in voltage between the “weight on” and
“weight off” conditions falls into specification.
11. Torque seal all potentiometers.
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