Load Operation; Key Scan - Samsung SR-L676EV Service Manual

2) Key Scan

The grid waveform of each output is supplied to each button line through switching diode
(IN4148). The grid #1 signal goes to the setting button of refrigerator. Then, refrigerator button
is pressed, around 4.5V goes to IC05(UAN2981A) pin 8 through key input line. MICOM detects
the refrigerator button pressed after MICOM pin1 receives the signal.

8. Load Operation

R-Defrost heater
COMP COOL FAN
SWING MOTOR
R-C/FAN
R-LAMP
F-LAMP
F-C/FAN
COMP.
F-Defrost heater
If MICOM outputs "high" signal to driver-IC(ULN 2803) according to each load operation
conditions, IC turns on and DC 12V flows to ground through the relevant relay coil. Then, core is
magnetized by the coil current, and relay contact switches on. When relay contact is on, AC POWER
is supplied to the relevant operation load, then which will be activated. If MICOM outputs "low"
signal, load operation stops with the relevant relay contact off.
Samsung Electronics
CON9
RED
9 9
7 7
5 5
3 3
1 1
CON10
9 9
7 7
5 5
3 3
SPK1-4
SQ-1201
1 1
CON8
5 5
3 3
1 1
V12
+12
RY01
RY02
RY03
RY04
RY05
RY06
RY07
RY08
(DC12V) +12
C27
104
RY09
IC06
18 1 (R-DEF-HET)
R03 C24
10K 104
(COMP-COOL FAN) 16
11 8
R
C
SWING MOTOR
I
12 7
N
E
(R CIRCLE-FAN)
13 6
T
W
15 4
O
R
K
15 3
(F CIRCLE-FAN)
17 2
18 1
Vcc GND
9
ULN2803
IC07
AC1
17 2 (F-DEF-HET) 15
C25
R02
10K
104
IC06
14 P05
P07
18 P11
19 P12
(R-LAMP) 21 P14
(F-LAMP) 22
P15
23 P16
(COMP) 24 P17
17 P10
P06
23