LG CF-29C44TM Schematic
ADJUSTMENT INSTRUCTIONS
*Alignment procedures
1.
It is safe to adjust after using insulating transformer between
the power supply line and chassis input to prevent the risk of
electric shock and protect the instrument.
2.Never disconnect leads while the TV receiver is on.
3. Don't short any portion of circuits while power is on.
4. The adjustment must be done by the correct appliances.
But this is changeable in view of productivity.
5. Unless other-wise noted, set the line voltage to 230V
10%, 50hz.
* Test Equipment required
1. VIF sweep generator
2. Color bar/cross-hatch pattern generator
3. DC power supply
4. Digital multi-meter
5. Color analyzer
Preparation for VCO & AFT Adjustment
1. Connect the measuring equipment to the TV as shown in
Fig.1
2. Set RF output level of Sweep S.G (Signal Generator) to
80dBuV.
3. Set Alignment Scope, Volts/Div to 100mV (VCO) or
1V(AFT), AC/DC switch to AC, Line/Ext switch to Ext.
IF Board (Component side view)
TP1
TP21
IC1T
IC2P
TP22
IC1P
TP6
TP2
TP25
TP20
J21P
AGC TP
L8P
VCO
L9T
VCO
L8T
AFT
TP4
TP24
TP5
VR1P
AGC
TP23
VR1T
IC1S
PIP Board (Component side view)
P502B
P2B
P2B
TU2P
AGC
TP3
P102BP103B P101B
NOTE: TP point is on the copper side of PCB.
L9P
AFT
DC POWER
SUPPLY
+
12 0.1V
-
¡
SWEEP S.G.
with Marker
(VP-8800G)
Alignment
Scope
3.3K
4.7K
0.01µF
1K
(VCO)
(AFT)
To TP2/ TP21
To TP5/ TP24
VCO : ON
AFT : OFF
To TP1/ TP20
To TP6/ TP22
To Pin5 of P101B
/ Pin7 of P1B
Fig.1:Connection Diagram of Equipment for VCO & AFT
Adjustment.
NOTE:
:PIP Board (Only 2 TUNER PIP Model)
* VCO (Voltage Controlled Oscillator)
Adjustment
Test Point: TP6 / TP22
Adjust: L9T / L8P
1) Turn on DC power supply.
2) Adjust Video Detector Coil (L9T / ) so that a
L8P
waveform on Alignment Scope is the same as below Fig.2.
ABCDEFG
Fig.2: VCO waveform on Alignment Scope
* AFT(Auto Fine Tuning) Adjustment
Test Point: PIN5 of P101B / PIN7 of P1B
Adjust: L8T / L9P
1) Turn on DC power supply.
2) Adjust IF AFT coil (L8T / ) so that 38.0 MHz (Vc) point
will be center as Fig.3.
L9P
A: 30.0MHZ
B: 31.5MHZ
C: 32.84MHZ
D: 36.8MHZ
E: 38.0MHZ
F: 39.5MHZ
G: 40.25MHZ
Adjustment procedures
1) Tune the TV set to receive a digital pattern unless
A
A: 36.8MHz
B: 38.0MHz
B
otherwise noted.
2) Press OK button on Control Board continuously and
yellow button on remote controller then you can find On
Screen Display. (Refer to the following Fig.4).
3) Press PR+ or PR- button for desirous function
adjustment.
4) Press VOL+ or VOL- button for correct picture.
5) Press OK button to memorize all the adjusted data.
[LINE SVC1] PR1
Fig.3: AFT waveform on Alignment Scope
* RF AGC (Auto Gain Control)Adjustment
Test Point: J1(on Main Board) / J22P
Adjust: VR1T / VR1P
The RF AGC control (VR1T/ VR1P ) was aligned at the time
of manufacture for optimum performance over a wide
range conditions. Readjust of VR1T/ VR1P should not be
necessary unless unusual local conditions exist, such as:
1) Channel interference in a CATV system.
2)Picture bending and/or color beats, which are unusually
due to excessive RF signal input when the receiver is
too close to a transmitting tower or when the receiver
is connected to an antenna distribution system where
the RF signal has been amplified.
In this case, the input signal should be attenuated (with
pad or filter) to a satisfactory level.
3) Picture noise caused by "broadcast noise" or weak
signal. If the broadcast is "clean" and the RF signal is at
least 1mV (60dBuV), the picture will be noise free in any
area.
Adjusting the VR1T/ VR1P (RF AGC) control to one end of
rotation will usually cause a relatively poor signal to noise
ratio;
Adjusting to the other end of rotation will usually cause a
degradation of over load capabilities resulting in color
beats or adjacent channel reference.
For best results, adjust the VR1T/ VR1P control while
performing on all over local channels, or the voltage at
J50(MAIN 1 Board) / J22P (PIP Board : OPTION) will be 5.5
+_0.1Vdc in RF level 60+_1dBuV.
VR1P
VR1P
VR1P
VR1P
J22P
H-CENT 11
V-CENT 02
SUB BRIGHT 10
SUB TINT 10
SECAM BELL 04
SECAM R-Y 08
SECAM B-Y 14
SECAM AMP 02
Fig.4
Horizontal center adjustment
Adjust so that the horizontal center line of digital pattern is in
accord with geometric horizontal center of the CPT.
Vertical center adjustment
Adjust so that the vertical center line of digital pattern is in
accord with geometric center of the CPT.
SECAM BELL filter adjustment
1) Tune the TV set to receive a SECAM digital pattern.
2)Adjust so that the color on the 3.8MHz pattern is
minimized.
SECAM B-Y/R-Y adjustment
1) Tune the TV set to receive a SECAM digital pattern.
2) Adjust so that the background color is equal to the PAL
background color.
* V
ertical center/Horizontal center/ SECAM
Adjustment
NOTE:These adjustments are already aligned at the time
of manufacture for optimum performance.
Readjust of them should not be necessary unless
IC2(EEPROM) is defective. Because all the
information of these adjustment are memorized in
that IC.
SECAM AMP adjustment
1) Tune the TV set to receive a SECAM digital pattern.
2) Adjust so that the level of SECAM color is equal to the
level of PAL color.
SUB BRIGHT/TINT adjustment
NOTE: This adjustment should be performed after White
Balance adjustment.
1) Tune the TV set to receive a broadcasting signal.
Adjust so that the brightness/TINT is optimum condition
2)
on the screen.
NOTE: If press OK button on Control Board continuously and
press continually two times yellow button on remote
controller then you can find On Screen Display as
follow Fig.5.
* Never change these data, these are important reference
data for TV.
[LINE SVC2] PR1
PEAK LIMITER OFF
P/N GP INITIAL
SECAM GP INITIAL
P/N AMP 0
AV-IN VOL 044
FM PRESCALE 031
NICAM VOL 108
SCART VOL 040
Fig.5
2)Tune the TV set to receive white pattern of PAL
standard signal.
3) Press OK button on Control Board continuously and blue
button on remote controller for obtaining a horizontal
line on the middle of CPT.
4) Turn the screen control of FBT counter-clockwise and
set it to the minimum position.
5) Turn the screen control of FBT clockwise slowly to
appear a horizontal line.
6) Adjust Cut-off volume(VR901, 902, 903) so that the
horizontal line may become white.
First, except the appeared color on the horizontal line
with one volume and then make to be white line with
the other two volume.
7) Turn the Screen control counter-clockwise for the
horizontal line to be complet cut-off.
8) Press OK button.
9)With a color analyer (white balance checker), adjust
VR904 and VR905 on the CPT Board to set X position
+_8 and Y position to 294+_8 (color temperature
to 279
is 12000
10)Control contast and brightness to be 4.5ft.L color
temparature, and adjust VR901 and VR903 so that the
screen may become white.
11) By varing contrast and brightness, whether you have
good adjustment in high and low light areas on the
screen.
If not, re-adjust above setp 3)
+_800) at the high light (45ft.L).
~10).
*Vertical Height (VH)/Horizontal Width
(HW)/Pin Cushion (PC) Adjustment
1) Tune the TV set to receive a digital pattern.
2) Set contrast to 100%, brightness and color to 50%
individually.
3) Adjust VR301(VH) so that the circle of the digital pattern
may be located within the effective screen of the CPT.
4)Adjust VR404(HW) so that the circle of the digital
pattern looks like exact circle.
5) Adjust VR403(PC) so that the outermost left and right
vertical line looks like parallel with vertical lines of the
CPT.
* Screen & White Balance (color temperature)
Adjustment
NOTE:This adjustment should be performed after
warming up for 15 minutes at least.
Test Point: Observing Display
Adjust: Screen Control of FBT
VR901, 902, 903 (Low Light)
VR904, 905 (High Light)
* Focus Adjustment
NOTE: This adjustment should be performed after
warming up for 10 minutes.
Test Point: Observing Display
Adjust: Focus control of FBT
1) Set color to minimum, brightness and contrast to
maximum individually.
2) Tune the TV set to an inactive channel station (snow
condition).
3) Adjust the Focus control for best overall focus.
1) Set VR901, 902, 903, 904, 905 on CPT Board to the
mechanical center position.
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