Samsung RSE8KPAS Service Manual page 80

Circuit Descriptions
The step signals of DC 11~2V will be generated periodically. If a sink signal outputs from IC4, DC 11-12V will be applied
to the LED input terminal and sink the LED output terminal to 0V. Therefore, LED will be ON for 2 miliseconds.
2) Key Scan
The 6 step signals, Q6~Q4 are applied to scan the 6 keys (buttons). When SW6 is pressed, the step signal 5V
from IC50 Q60 will be amplified to 12V and entered to the panel PCB.
This signal will reach to SW6 throogh CN50 pin2, and 12V signal enlered to CN50 lst pin during SW6 being
pressed.
The signal (DC 12V) will be reduced to 5V by R502 and R501, and ented to the MICOM 29 at the same time of
output signal of Q6, then MICOM will match a corresponding function for SN6 is pressed.
2-1) IC50 Q6(5V) → IC51 NO3(5V) → IC51 NO16 (12V) → VN50 NO2(12V) → Panel PCB Connector NO2(12V)
→ SW6 → Panel PCB Connector NO1(12V) → CN50 NO2(12V) → R502/R5.1 → Voltage Down(5V) →
Input MICOM NO29(5V)
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