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N-180 Pulse Oximeter Service Manual
b.
4.
Select RAM location three in OXYGEN SATURATION
display. This is the location that represents the sensor RCAL
value. The number in the PULSE RATE display must equal
63.
This step verifies proper operation of the rcal determination
system when a pulse oximeter tester is connected.
Select RAM location four in OXYGEN SATURATION display.
This is the location that controls the INAMP gain component.
A nominal reading of 15 to 30 means SAT INAMP automatic
gain circuit is operating correctly.
Remove oximeter tester from sensor input and connect NELLCOR
D-25 sensor. Leave sensor open and face down on table.
Note:
The sensor disconnect alarm sounds. Press the audio alarm
off button if you want to remove the alarm.
Check red LED intensity as follows:
a.
b.
Cover detector of the D-25 with opague material.
Select RAM location five in OXYGEN SATURATION display.
This is the location that controls the red LED intensity. The
number in the PULSE RATE display is over 200 (maximum
equals 255).
Uncover detector.
Move sensor LEDs closer to sensor photodiode.
Notice that increasing the light near the photodiode makes
the LED intensity decrease.
Cover detector again.
Read value of RAM location four and then read location five.
Note the value of location five has also decreased. The lowest
values is less that 50.
Open sensor (move LEDs away from photodiode).
After 10.
+
Ater
+U-
seco
to-hieh-i
+
seconds, the LEDs return to high intensity-
Read RAM location four, and then read location five.
Note the value of location five has also increased.
Check IR LED intensity as follows:
Cover detector of the D-25 with opaque material.
Select RAM location six in OXYGEN SATURATION display.
This is the location that controls the IR LED intensity. The
number in the PULSE RATE display is over 200 (maximum
equals 255).
7-8
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Table of Contents
Troubleshooting
