Technical Supplement
S-3
S3
CIRCUIT ANALYSIS
The following paragraphs discuss the operation of each of the printed circuit
boards within the NPB-190 pulse oximeter. (Refer to the appropriate schematic
diagram at the end of this supplement, as necessary.)
S4
FUNCTIONAL OVERVIEW
The monitor functional block diagram is shown in Figure S4-1. Most of the
functions of the NPB-190 are performed on the UIF PCB. Functions on the UIF
PCB include the SPO
2
module, PIC, CPU, and Memory. Other key components
of the NPB-190 are the Power Entry Module (PEM), Power Supply, and the
Display PCB.
The Display module consists of the LED display and the Membrane Panel.
Contained on the Membrane Panel are enunciators and push buttons, allowing
the user to access information and to select various available parameters. The
Display PCB contains; SpO
2,
heart rate, and Blip Bar LEDs, and their associated
driver circuits.
SPO
2
Module
80196
CPU
Power Supply
Membrane
Panel
LED Display
PIC
Serial port
Alarm Speaker
Battery
Charger
DC
Supply
UIF PCB
Power
Entry
Module
Fuses
Patient
Connection
Flash ROM
64K
System RAM
EEPROM
On/Off Switch
Battery
Figure S-2: NPB-190 Functional Block Diagram
S5
AC INPUT
A selector switch on the back of the NPB-190 allows the user to connect the
monitor to AC power ranging from 100 VAC to 240 VAC. The switch has two
positions, one for 100 VAC through 120 VAC and one for 200 VAC through 240
VAC. Verify that the switch selection matches the AC power at your location
before plugging the monitor into an AC outlet.
AC power enters the NPB-190 through the Power Entry Module (PEM). Both
the Line and Neutral lines are protected by a 0.5 amp fuse. These user-accessible
fuses are located in a fuse drawer, which is part of the PEM located on the back
of the monitor.
