Samsung SR-S25NTA - Page 28

8-6.
KEY
SCAN
and
DISPLAY
circuit
part
)
ce
PANEL
PCB
P04
43
=o
OHO
p03
@
Seb
ee
lao
P03
pe
ae
lol
it
ae
6
ee
ERE
Wes
|
=
ele
P76
@
OH
OH®
pee
ppt
x
=
ee
bo
ses
—
1011}
ah
ne
oe
amare
01
=
ee
aay
cee
ted
P72
@)
Oi)
OH®
>
oe
are
Se
[AE
S06: R505
6.8K 6.8K
P71 @)
P70 |
7501
4.
Running
of
KEY
SCAN
and
DISPLAY
As
shown
in
the
following
waveform
of
each
part,
“High”
output
is
sent
in
turn
from
MICOM
PIN
#3
3
#4
—
#5
—
#6
—+
#7
for
2
msec
at
10msec
interval
using
five
Terminal
of
MICOM
NO
#3,
4,
5,
6,
and
7.
This
signal
appears
at
OUTPUT
Terminal
through
INPUT
Terminal
of
1C05
(UDN2981
or
UPA2981C).
At
this
time,
PEAK
TO
PEAK
voltage
of
square-wave
is
about
11
V
(DC
RMS
1.5
V)
and
output
waveform
is
as
follows.
V
GRID
#1
GRID
#2
GRID
#8
GRID
#4
V
GRID
#5
nen
‘
t
'
1
ot
t
_ 2.KEY SCAN
When
GRID
#1
waveform
is
outputted,
this
signal
is
supplied
to
the
button
for
temperature-setting
of
freezing
room
through
resistance
10
KQ.
At
this
time,
when
you
push
button
for
freezing
room,
the
signal
becomes
decreased
by
R506
(6.8
KQ)
and
about
4.5
V
of
PEAK
TO
PEAK
voltage
is
approved
to
MICOM.
After
supply
of
about
4.5
V
of
PEAK
TO
PEAK
voltage
to
MICOM,
MICOM
can
judge
that
GRID
#1
waveform
is
inputted
and
then,
change
the
temperature-setting,
for
freezing
room.
Like
this
way,
each
GRID
waveform
is
perceived.
RED-RED
BLU-BLUE
ORG-ORANGE
BRN-BROWN
PNK-PINK
GRY-GRAY
WHT-WHITE
YEL-YELLOW
BLK-BLACK
PRP-PURPLE
W/BLK-
WHITE/BLACK
S/BLU-
SKY BLUE