Nellcor Oximax NPB-40, Service Manual

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Technical Discussion
78
The NPB-40 consists of two printed circuit boards (PCB), the user interface PCB
and the SpO
2
PCB. The relationship between these two components and their
interconnections is shown in the NPB-40 block diagram. See Figure 26.
Figure 26: Block Diagram
SpO
2
Printed Circuit Board
The SpO
2
PCB provides patient interface and NPB-40 operating power.
Patient Interface
The patient interface receives signals from the O
XI
M
AX
patient sensor. These
signal are converted and supplied to the user interface PCB central processing unit
(CPU). The patient interface receives control signals from the CPU. These control
signals are used to control the light emitting diodes in the
O
XI
M
AX
patient sensor.