MPS450 SERVICE MANUAL FUNCTIONAL DESCRIPTION
8
CIRCUIT DESCRIPTION
INTRODUCTION
Refer to the Equipment-Relationship Illustration in Chapter 1, “General Information.” As shown in the
illustration, the MPS450 comprises three printed circuit assemblies (PCAs), each portrayed as a
separate block on the diagram:
Digital Assembly
Analog Assembly
ECG Post Assembly
Each of these circuit blocks is described below. (See also the MPS450 PCA images, available in the
section called “Top-Level Assembly” in Chapter 6, “MPS450 Parts.”)
DIGITAL PRINTED CIRCUIT ASSEMBLY
The Digital PCA is the location of the microcomputer that controls all instrument functions, as well as
general power supplies and digital circuits:
o Power on/off control
o Power supplies
± 5 V
o MicroController:
Microprocessor
RAM
FLASH
EEROM
Timers
Serial ports
o Keyboard Interface
o Display interface
o RS-232 port:
Level shifters
Transmitter/receivers
Digital/Analog PCA interface
o Connectors:
External power-source connector
Internal power-source (battery) connector
Display connector
Digital/Analog PCA connector (controls patient-simulation circuits)
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