SR23 - 923-03509 3-5 CS - SERVICING
CIRCUIT OVERVIEW (continued)
TDA6120Q
MIRROR
CASCODE
CASCODE
1x
1x
CURRENT
INPUT
1x
IN
OUT
1x
IN
OUT
4xOUT
MIRROR
4x
IN
OUT
J 5mA
1
3
4
8
6
9 11
5
10
12
13
7
2
+
0.7 pF
V
CC
V
DD
IN
OUTC
OUT
OUTM
GND
VIN+
RC+
RC-
VIN-
a.c.
AKB Circuit
The factory adjust of cut off is based on this system.
The processor moves the reference pulse according to
the level indicated on the cut off register. When the
reference pulse is moved, the AKB system moves the
black level of the signal. This is the way it adjusts the
white balance at low contrast.
ABL CIRCUIT
ABL (Automatic Blanking Level) and ACL (Automatic
Contrast Level) are circuits designed to protect the CRT
against over-current of electron beams that will burn
the screen phosphors. Both circuits limit the current
flowing to the screen. For 27-inch sets, the beam
current is limited to 1.5 mA. For 32 and 36-inch sets
the beam current is limited to 1.6 mA. The ABL controls
the current by affecting the black level and the ACL by
limiting the contrast.
The ICX2200 Video processor has two ABL modes of
operation: Picture only and Picture/Brightness. The first
one only affects the contrast level. This first mode is
also called ACL. The second option affects Contrast and
Brightness. This option is a mix of ABL and ACL. Both
options are selected by software. The Picture only mode
is fixed.
AUDIO PROCESSING
STEREO MODULE
There are five different Audio sources: Antenna/Cable,
Aux video, S-Video, Rear Computer, and Front Computer/
Front Video.
The Tuner/IF section processes the Antenna/Cable
signal. It then passes as Composed Audio to the audio
processor to be demodulated.
IC1400
221-01127
ICX2900
221-01053
VIDEO/AUX
S-VIDEO
COMPUTE
REAR
(SVGA/NTSC)
COMPOSITE
VIDEO FRONT
TUNER/IF
COMPOSITE AUDIO
IC801
221-01145
Rear Jack Packs
Front Jack Packs
Antenna/Cable
A/V Switch
Audio Processor
Transistor Variable
Audio Output Monitor
MicroProcessor IIC Bus
R-IN
L-IN
R-IN
L-IN
R-IN
L-IN
R-IN
L-IN
ROUT T
LOUT T
AUX1-R
AUX2-L
LSOUT-R
LSOUT-L
Vol, Bass, Treble,
Balance, SoundRite,
SEQ
COMP-IN
R-IN
L-IN
SPKR-R
SPKR-L
AUX-R
AUX-L
SDA
SCL
SDA
SCL
PWR MUTE
10
8
16
14
22
20
6
4
39
40
2
5
6
7
3
9 10 26 27
11
7
41
39
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