10-1) Source Power Circuit; 10-2) Oscillator Circuit; 10-3) Reset Circuit - Samsung RS21 Service Manual

Circuit Descriptions

10-1) Source Power Circuit

This circuit shows SMPS(Switch Mode Power Supply) which converts AC input voltage (230V, 50Hz) to a high DC
voltage (about 320V). The input AC source power is converted to DC through a wave rectifier (BD1) and the converted
DC power will generate a constant waveform on the switching transformer using a high speed (100KHz) switching motion
of TOP223Y. The D104 will rectify the generated voltage and transform into a steady 12V DC source power used for the
digital display panel and relays. The regulator (KA7805) finally transforms into 5V DC source power for the control board
and sensor's circuits.
Caution) Be careful to handle this circuit due to high voltages (AC115V, DC170V)

10-2) Oscillator Circuit

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.

10-3) Reset Circuit

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
Xin(#30)
Xout(#31)
Terminal
Vcc
RESET
44
Oscillation Frequency
4MHz
4MHz
Voltage
DC 5V
DC 5V