Samsung RS21 Service Manual

Also see for RS21: User manual

Contents

44Circuit Descriptions10-1) Source Power Circuit10-2) Oscillator Circuit10-3) Reset CircuitTerminal Oscillation FrequencyXin(#30)Xout(#31)4MHz4MHzThis circuit shows SMPS(Switch Mode Power Supply) which converts AC input voltage (230V, 50Hz) to a high DCvoltage (about 320V). The input AC source power is converted to DC through a wave rectifier (BD1) and the convertedDC power will generate a constant waveform on the switching transformer using a high speed (100KHz) switching motionof TOP223Y. The D104 will rectify the generated voltage and transform into a steady 12V DC source power used for thedigital display panel and relays. The regulator (KA7805) finally transforms into 5V DC source power for the control boardand sensor’s circuits.Caution) Be careful to handle this circuit due to high voltages (AC115V, DC170V)This is oscillator circuit to generate synchronous clocks used to calculate the time for the microprocessor operation.Note) If the specification of a resonator changes, micro-processor can not work properly.The reset circuit is to initialize the values RAM ＆ other sectors of micro-processor. When the power is engaged initially,the reset voltage becomes “Low,” and it keeps “High” in the normal operation.Terminal VoltageVccRESETDC 5VDC 5V