LG CF-20F69, CF21F39, cf20j50k ADJUSTMENT
- 1 -
Y Safety Precautions
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 otherwise noted, set the line voltage to 230Vac!10%,
50Hz.
Y Test Equipment required
1. RF signal generator (with pattern generator)
2. DC Power Supply
3. Multimeter (volt meter)
4. Oscilloscope
5. Color analyzer
:
RF AGC (Automatic Gain Control) Adjustment
The RF AGC was aligned at the time of manufacture for
optimum performance over a wide range conditions.
Readjustment of RF AGC 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 (60dBu), the picture will be noise free in any area.
Adjusting RF AGC 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 interference.
: Screen Voltage Adjustment
1) Input the Color Bar Pattern into Antenna jack.
2) Select CutOff of SVC-3 mode.
3) Turn the screen control clockwise until the Horizontal line
is visible and turn it counterclockwise until the Horizontal
line is faintly visible.
: Focus Adjustment
NOTE: This adjustment should be performed after warming
up for 10 minutes.
1) Input the Color Bar Pattern into Antenna jack.
2) Adjust the Focus control of FBT for best overall focus.
: VCO Adjustment
1) Input Digital Pattern into Antenna jack.
2) Select A-PIF of SVC-4 mode.
3) Press VOL
F/G button and A-PIF will be changed 0 to 1
while the number of PIF-C is rolling.
4) When PIF-C stops rolling, A-PIF will be changed 1 to 0 and
VCO adjustment is finished.
Caution : Do not press the Volume button again in A-PIF mode
after adjustment is finished.
Adjustment
1. Connect RF signal (65dB!0.5dB) and turn on the TV.
2. Press OK buttons on TV set and Remote Controller at the
same time to get into SVC mode.
3. Press Channel UP/DOWN button on the Remote Controller
several times to find AGC.
4. Press Volume UP/DOWN button until the AGC Voltage is
the same as the Table below.
5. Press OK(Y) button to memorize the data.
1. To get into SVC mode
1) Press OK buttons on both TV set and Remote Control at
the same time.
2) Press Yellow button to select OPTION-1, OPTION-2,
OPTION-3 or OPTION-4.
3) Press PR E/D button to select an adjustment.
4) Press VOL F/G button to change the data.
2. To memorize the adjusted data into EEPROM
Press OK button.
3. To get out from SVC mode
Press TV/AV or Power button.
Test Point : AGC TP (J17)
Adjust : Remote Control
Test Point : RK (Red Cathode of CPT Board)
Adjust : Screen Control of FBT
TUNER
AGC Voltage
Default AGC Data
6700VPV002A(LG C&D)
2.5
!
0.1V
24
6700VPV002B(LG C&D)
3.0
!
0.1V
24
Test Point : Observing Display
Adjust : Focus control of FBT
ADJUSTMENT
- 2 -
: Deflection Data Adjustment (Line SVC-2)
1. Preparation for Adjustment
1) Select SVC-2 Mode.
2) Tune the TV set to receive Digital Pattern and set ARC
Mode to Standard.
2. Initial deflection data and average data for CPT
3. Adjustment
1) VL(Vertical Linearity) Adjustment
Select VL adjustment mode to adjust the upper and lower
vertical size to be the same for horizontal center line.
2) VS(Vertical Shift) Adjustment
Adjust the geometrical horizontal center line of the screen to
be coincided with the vertical center line of CPT.
3) VA(Vertical Amplitude) Adjustment
Adjust the upper and lower part of big circle of the received
pattern to be placed on 6~7mm from the valid screen.
4) HS(Horizontal Shift) Adjustment
Adjust the geometrical vertical center line of the received
screen to be coincided with the horizontal center line of CPT.
5) SC(Vertical S Correction) Adjustment
Adjust the width of upper/center/lower grid of the received
pattern to be the same.
: SECAM Background Color Adjustment(CT-, CF-)
1. Preparation for Adjustment
Select ÒS R-YÓ or ÒS B-YÓ of SVC Mode 4.
2. Adjustment
While switching SECAM and PAL channels in turns, press VOL
F/G key until the background color of SECAM channel to be
the same as that of PAL Pattern at S R-Y or S B-Y.
: White Balance Adjustment.(LINE SVC-1)
NOTE : This adjustment should be performed after screen voltage
adjustment.
1) Tune the TV set to receive 100% white pattern.
2) Select SVC-1 Mode.
3) Press PR UP/DOWN key to select BG, GG, BG, GC.
Adjust BG, GG on Brightness 40!
1FL and BG, GC on
Brightness
4.5!
0.5FL with VOL
F/G
key to get the color value.
4)
Adjust BG, GG from the initialized data to get the color value of
X=281
!
8, Y=288!8.
5) R,G,B initial data and average data
: Sub Brightness Adjustment
NOTE: This adjustment should be performed after White
Balance adjustment.
1) Input FUBK pattern to Antenna jack.
2) Select S-BRI of SVC-3 mode.
3) Press VOL F/G until (a) and (b) of FUBK are distinct and
press VOL G twice more.
: OPTION Adjustment (SVC MODE:OPTION-1,
OPTION-2)
NOTE: When the EEPROM has been replaced, the Option
data should be restored as the function of individual
system and specification.
1) Press OK buttons on both TV set and Remote Controller at
the same time to get into SVC mode.
2) Press the Yellow button several times to find OPTION-1 or
OPTION-2.
3) Input the correspond OPTION data referring to Table below
with the numeric buttons 0~9.
Status
RC
GC
BC
GG
BG
Initial Data
127
147
123
59
64
Remark
VL
VS
VA
HS
SC
9
3
37
11
2
Status Default
9
3
34
12
2
21" LG
9
1
39
10
2
20" LG
9
3
37
11
2
14" LG
(a) (b)
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