CASMED 740 MONITOR SERVICE MANUAL21-02-0174 REV. 02 05/0866THEORY OF OPERATIONThe CASMED 740 Monitor’s Main Control Board provides the following functions for theoperation of the monitor.• Power Supplies• Battery Charger• Supervisor Microcontroller (Microchip PIC 16F73)1. Indicator LEDs2. Temperature Monitoring3. Power Smart Module4. Power ON/OFF and Reset to Digital Signal Processor Controller5. Monitor ON/OFF6. Communication with Digital Signal Processor Controller7. Monitor Battery Charger and Battery conditions• Digital Signal Processor Controller (Motorola DSP 56F827)1. SpO2 Monitoring2. Blood Pressure Monitoring3. Keypad Monitoring4. Indicator LEDS and Displays5. Real-Time Clock6. Alarms7. Serial InterfacePOWER SUPPLIESThe input to the 740 Main Control Board comes from either the DC input (J1) or the BatteryInput (J2). A Control chip (U6) is responsible for selecting the monitor’s main power source.The DC input, from the Power Supply, always takes priority over the Battery.Battery 7.2 Volts @ 4.0 Ahr (TP7 to TP33)DC 12 Volts @ 28 Watts (TP28 to TP29)There are several supplies that are generated for internal use.+Vpic TP5 The power supply for the Microchip PIC16F73 (U5), the Supervisor of theCASMED 740 Main Control Board.The DC input or the Battery input, if there is no DC present, goes into a voltage regulator (U4) tosupply the +3.3 volts.+5V TP1 Power supply voltage for the main Analog and Digital circuitry.The DC input or the Battery input, if there is no DC present, goes into a switching regulator (U1)to supply +5 volts. The regulator is turned on and off by the Microcontroller (U5).