
CAUTION
: If a sensor is attached, remove it prior to running the following test.
1. Switch off the N-20P; open the battery door and remove the batteries.
2. Set the power supply's voltage to 5 VDC, and connect the supply to the battery clips of the N-20P –
ensure
that polarity is correct.
3. Switch on the N-20P; verify complete POST (the N-20P should operate normally).
4. Decrease the power supply voltage to 4.0 VDC or slightly below. Then, press the battery check button;
within 15 seconds, the Low Battery indicator should illuminate and the lowest two segments of the battery
level meter should illuminate; the sensor LEDs should remain lit; and, printer operation should cease.
5. Decrease the power supply voltage to 3.45 VDC or slightly below. Then, press the battery check button;
within 15 seconds, the Low Battery indicator should begin to flash and only the lowest segment of the battery
level meter should illuminate.
6. Decrease the power supply voltage to below 3.2 VDC. Within 15 seconds, the N-20P should turn itself off.
Pressing the measure button should not turn the unit back on.
7. End Low Battery test.
Performance Testing
The N-20P will operate in conjunction with the NELLCOR pulse oximetry tester, model DRC-1, to test
instrument performance. The SRC-1 plugs into the DB-9 sensor connector and uses the instrument's power
supply and diagnostic software to test the display, the accuracy of the oximetry values and the operation of the
instrument. Nellcor recommends routine performance testing at 1-year intervals. Refer to the SRC-1 operator's
manual for details on performance testing with the SRC-1.
Other tests, which are outlined below, include the display backlight test, the low battery test, and the thermal
printer test.
Backlight Test
The electroluminescent backlight illuminates the display in three sections: (1) the main section, ie., the Oxygen
Saturation and Pulse Rate display fields, and the 14-segment pulse rate amplitude indicator; (2) the Low Battery
indicator and (3) Pulse Search indicators each have their own backlight. Each backlight flashes once during
POST.
The ambient light is located underneath a small circular window in the top right corner of the N-20P display.
Under low light conditions, the main section backlight is switched on. If a Low Battery and Pulse Search
indicator is lit, its backlight is also lit.
To test for proper operation of the display backlight, observe the N-20P in a darkened room. If any backlight
section is not working correctly, contact Nellcor's Technical Services Department or Nellcor's local
representative for assistance.
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