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Troubleshooting
4-2
If the N-20PA does not perform as expected, the problem may be related to the
following:
•
Incorrect sensor placement.
•
Depending on concentration, indocyanine green, methylene blue, and other
intravascular dyes may affect the accuracy of a measurement.
•
These instruments are calibrated to read oxygen saturation of functional
arterial hemoglobin (saturation of hemoglobin functionally capable of
transporting oxygen in the arteries). Significant levels of dysfunctional
hemoglobins such as carboxyhemoglobin or methemoglobin may affect the
accuracy of a measurement.
If the electronics or display functions, or both, require testing, refer to the
Performance Verification section.
Table 4-1 : Troubleshooting the N-20PA
Symptom
No response to On/Off
button.
Pulse Search indicator
appears for more than
5-10 seconds.
Possible Cause
1. Battery access door may
not be properly latched.
2. Batteries may be
discharged.
3. Batteries may be
incorrectly installed.
4. Batteries may not be
making proper electrical
contact.
5. Fuse F1 on the auxiliary
PCB may be open.
6. Dust may have
accumulated under On/Off
button causing loss of
electrical contact.
1. Sensor may be improperly
positioned.
2. Incorrect sensor may be in
use.
3. Perfusion may be too
low.
4. Foreign material on the
Recommended
Action
1. Check access door and
ensure that it is properly
latched.
2. Exchange batteries for a
new set.
3. Ensure that batteries are
oriented according to the
polarity indicator.
4. Inspect battery contacts
for deformity; clean contacts
to remove oxidization.
5. See Section 4.7.5,
Replacing Fuses.
6. Clean contact points under
On/Off button (see Section
5.2.1, N-20PA Disassembly
Procedures).
1. Ensure that the sensor is
correctly applied (see sensor
Directions for Use).
2. See sensor Directions for Use
to ensure that the patient's
weight and sensor application
are correct. Test the sensor on
another person to verify proper
operation.
3. Check patient status. Test the
instrument on someone else, or
try another type of sensor. The
N-20PA will not make a
measurement if perfusion is
inadequate.
4. Clean the test area and ensure
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