Introduction; Manual Overview; Warnings And Cautions; Description Of N-20 Portable Pulse Oximeter - Mallinckrodt Nellcor N-20 Service Manual

1 INTRODUCTION

1.1 Manual Overview

1.2 Warnings and Cautions

1.3 Description of the N-20 Portable Pulse Oximeter
1.1 Manual Overview
This manual contains service information for the Nellcor
N-20/N-20P, that is necessary to maintain and repair the N-20/N-20P by qualified service personnel.
Note that models designated for sale in Europe differ from models designated for sale in the USA only
in that the user control buttons and display use icons rather than alphabetical characters, and that the
product labels reflect the appropriate European certifications and company addresses.
1.2 Warnings and Cautions
"WARNING" is used to call attention to procedures that could result in an error in calibration or
performance, and/or precautions that are important to ensure the safety of both service personnel and
patients.
"CAUTION" is used to call attention to procedures that should be carefully followed to prevent
damage to the instrument.
1.3

Description of N-20 Portable Pulse Oximeter

The Nellcor portable pulse oximeters model N-20 (without printer) and N-20P (with printer) provide
noninvasive and continuous information about the percent of oxygen that is combined with
hemoglobin (SpO
pulse activity and patient perfusion. These instruments can be operated in either spot-check mode
(single-measurement), or extended-measurement mode (30 minutes of data). Patients are connected to
the instrument by a Nellcor oximeter sensor. The sensor LEDs are driven by the SpO
which also conditions the incoming signals, and provides CPU adjustable gains stages. The CPU
measures the sensor's analog outputs, continually controls the gain stages, and calculates SpO
The N-20/N-20P is automatically calibrated each time it is switched on, and whenever a new sensor is
connected; it sets sensor-specific calibration coefficients by reading a calibration resistor in the sensor.
Also, the intensity of the sensor's light sources is adjusted automatically to compensate for differences
in tissue thickness and skin color.
Standard user controls consist of a Measure button and a Check-Battery button. The Measure button
signals the power control circuit to switch on the power supply. The power supply then provides
regulated power to the unit. Once power is on, the CPU reads both the Measure and Check-Battery
buttons for user commands.
The N-20P printer provides a hard copy of acquired patient measurements. The printer circuit
includes three user control buttons: ON (on/off), ADV (advance), and D/D (day/date). In addition, an
ambient temperature sensor is used with the battery voltage input to control printout quality.
) and pulse rate. A pulse amplitude indicator provides a qualitative indication of
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portable pulse oximeter, models
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analog section,
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.
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