Samsung SR-L628EV - Key Scan & Display Circuitry; Key Scan & Display Waveforms

10
9
4
3
2
1
5
6
7
8
11
10
9
4
3
2
1
5
6
7
8
11
10
9
4
3
2
1
5
6
7
8
11
X4 X5 X6
1N4148
C C-N N N-W W
C C-N N N-W W
X1 X2 X3
Alarm
X-Flow Quick FRE
Quick REF
HIGH
HUMI
S/W01
S/W02
S/W03
S/W04
S/W05
1N4148
1N4148
1N4148
1N4148
KEY INPUT
4. 7 K
R04
R502
1.2K
R503
1K
18
17
16
15
14
6
9
GRID 05
GRID 04
GRID 03
GRID 02
GRID 01
IC05
IC04
1
2
3
4
5
13
10
6
5
4
3
2
1
P75
P74
P73
P72
P71
P70
P04
P03
P02
P01
P00
13
12
11
10
9
3
4
5
6
7
9
8
16
15
14
13
12
10
GND VCC
UDN2003(2803)
C23
104
CON7
(XH-11P)
+12
Quick
REF
F Temp. R Temp.
Quick
FRE
R501
3K
C501
3K
V
O
Grid #1
t
V
O
Grid #2
t
V
O
Grid #3
t
V
O
Grid #4
t
V
O
Grid #5
t
2 m Sec 8 m Sec
11V
22 Samsung Electronics
1) Key scan and display operation
As shown in the following waveform, MICOM pins #2 ~ #6 output are high for 2msec per 10msec.
MICOM pin #2 → #3 → #4 → #5 → #6 output repeats. The signal is output through IC05(UDN
2981A). At that time, the peak to peak voltage of square signal registers around 11V. The grid #1 ~#5
waveforms are as follows.
Refrigerator Display
Freezer Display
Letter Display
“V” Function Display
“V” Function Display
7. Key scan and display circuitry