Novametrix Medical Systems MARS PO2 TECH 2001, Руководство по обслуживанию

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Rev. 01 Model 2001 Service Manual
9
Section 4
Theory of Operation
The Model 2001 is a microprocessor based instrument that measures the clinical parameters
of oxygen saturation (SpO
2
) and pulse rate. The system contains all the circuitry necessary for
controlling, collecting, conditioning and displaying patient information gathered from the
Superbright™ sensors. The theory of operation of the Model 2001 is explained in detail in the
subsections that follow. Refer to the Schematic and Assembly Drawings for further information.
2726 Power Supply Board
The 2726 Power Supply Board contains the circuitry needed to power the monitor from the AC
Mains (line voltage). The power supply board also connects to the battery and contains the
battery charging circuitry.
AC Mains and Battery Operation Overview
The Model 2001 can be powered from its internal 12 volt battery or from the AC Mains. The
green (sine wave icon) front panel indicator illuminates when the line cord is connected and the
rear panel power switch is in the “|” (On) position. This indicates that AC Mains power is
reaching the power supply, that the battery is being charged, and that if the monitor is turned
on, it is being powered from the line voltage.
If AC Mains power is removed by unplugging the line cord or setting the rear panel power switch
to the “0” (Off) position, the monitor will operate for up to four hours from its internal 12 volt lead-
acid battery. As the battery voltage runs low (<11.5 volts), the red battery indicator on the front
panel illuminates. At this point, the AC Mains should be reconnected to power the monitor and
charge the battery.
If the monitor continues to be powered from a battery in a low voltage situation, at approximately
11 volts, a continuous alarm sounds for thirty seconds while the Message Center displays
BATTERY EXHAUSTED CONNECT LINE CORD. If this alarm/message is ignored, the monitor
displays will shut down and the battery indicator will flash on and off about every 5 seconds. If
AC power is now restored, the monitor will re-initialize (go through the power up and self-test
routines) and resume normal operation. However, continued battery operation will eventually
activate a hardware low voltage circuit (<8.5 volts) that shuts the monitor off to prevent damage
to the battery. Once the unit is shut down with the hardware circuit, the AC Mains must be
connected and the front panel POWER key pressed before the monitor will turn back on.