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2-12 Power On/stand-by
circuit (RC Transformerless
model)
O Power On/Stand-by
The power on/stand-by
signal is outputted from pin 48 of CPU.
When the stand-by mode is selected the voltage of pin 48 changes from Hi(5V) to Low(OV)
to turn on Q703 and Q715, and turns off Q552.
Q552 turning off causes Q551 and Q554
to turn
off.
B4 +24V
supply
for vert. & horiz.
output
circuit,
B7 +8V supply
for
lF/Video/Chroma
circuit and B6 +12V for tuner circuit are all cut off, resulting in the TV set
going into the stand-by mode.
At the same time, Q703 causes LED D803 to illuminate and indicate the stand-by mode.
When the TV is switched back into the power on mode, Q551 and Q554 are turned on and
the relevant voltages are supplied back to each circuit.
.—. —.—
.—
.,.....................
..."
0551
~
:... ..-..y
.
VerL&Horiz
;
i
~
output
"."+....*
,
circuit
i
0554
; ..........7 k.
—.—.
—.—;
..... ..........
;
05
.—. —.—
.—
;
::
:
15V
7
;:
:.....+ ....... :
:
:<
~ Power
~
.—. —.—
.—.
~ supply
-
'--I
; circuit
:
.—. —.—.
—.
;
~
I-Gacb
~ s ..
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
l . . . . . .1
. . . . ._
. . . .l-m
f=+= I
CPU
R808
330
/'
D803
5v—-—-
1
fi
'p"e-
Power On
Stand-By
.............................Ov
-19-
A7-A
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