Samsung RB1955SWRB1955SH, Service Manual

Page: 28 / 62

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Circuit Descriptions
When the power is supplied to MICOM, the reset
circuit initializes RAM and other sectors of MICOM.
A reset voltage maintains “low” for hundreds of µsec
comparing to MICOM Vcc voltage when the power is
in. It also maintains “high”(5V) during normal
operation. But, when Vcc drops to 3.4V-3.7V, a reset
port becomes “low”.
Port
Vcc
Reset
Voltage
DC 5V
DC 5V
1) If a door is open, the door S/W contact is closed. Then MICOM receives “low” signal and
detects door open, A relay control circuit receives “HIGH” signal and turn Lamp on.
2) If a door is closed, the door S/W contact is open. Then MICOM receives “high” signal and
detects door close, A relay control circuit receives “LOW” signal and turn Lamp off.
DOOR
F
R
Door Conditions
CLOSE
OPEN
CLOSE
OPEN
Door S/W Contact
OPEN
CLOSE
OPEN
CLOSE
MICOM
PIN NO
# 39
# 40
Micom Input Voltage
“HIGH”
“LOW”
“HIGH”
“LOW”
10-3)Reset Circuit
10-4) Door S/W Sensing Circuit