Service Manuals, User Guides, Schematic Diagrams or docs for : LG TV DI-28Z12 Lg_tv_DI-28Z12
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ADJUSTMENT
Y Safety Precautions
1. It is safe to adjust after using insulating transformer
between the power supply line and chassis input to Test Point : J189 or Observing Display
prevent the risk of electric shock and protect the Adjust : VR101
instrument.
2. Never disconnect leads while the TV receiver is on. The RF AGC control (VR101) was aligned at the time of
3. Don't short any portion of circuits while power is on. manufacture for optimum performance over a wide range
4. The adjustment must be done by the correct appliances. conditions. Readjust of VR101 should not be necessary
But this is changeable in view of productivity. unless unusual local conditions exists, such as:
5. Unless otherwise noted, set the line voltage to
230Vac!10%, 50Hz.
Y Test Equipment required AGC TP.
IF Board
1. RF signal generator (with pattern generator) 1[EA] J189
2. DC Power Supply
3. Digital Multimeter (volt meter) 2[EA] Tuner
Digital
4. Oscilloscope 2[EA] Multimeter
5. White balance meter 1[EA]
VR101
(AGC ADJ.)
: VCO (Voltage Controlled Oscillator) Adjustment Fig. 2 : Connection Diagram of Equipment for AGC Adjustment.
1) Channel interference in a CATV system.
Test Point : J72
2) Picture bending and/or color beats, which are unusually
Adjust : L107
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
Ceramic
CAP.
signal has been amplified.
38.9MHz
10000pF In this case, the input signal should be attenuated (with
RF
IC102
Signal
TDA9815
pad or filter) to a satisfactory level.
generator Multimeter &
oscilloscope 3) Picture noise caused by "broadcast noise" or weak signal.
3 4 5
Ceramic L107
2.85Vdc If the broadcast is "clean" and the RF signal is at least
CAP. Z101
10000pF G3962
(VCO ADJ.) 1mV (60dBu), the picture will be noise free in any area.
J72
GND Adjusting the VR101 (RF AGC) control to one end of rotation
IC01 will usually cause a relatively poor signal to noise ratio;
u-COM
L106 Adjusting to the jother end of rotation will usually cause a
5Vdc
Power degradation of over load capabilities resulting in color beats or
Supply
C115(-) adjacent channel reference.
GND L01
Adjustment (Refer to Table 1)
Fig.1 : Connection Diagram of Equipment for VCO Adjustment.
VL (Vertical Linearity)
1) Turn on DC power supplies. Adjust so that the boundary line between upper and lower
2) Adjust Video Detector Coil (L107) for 2.85! 0.1Vdc. half is in accord with vertical blanking line.
NOTE : The condition of signal Generator.
VS (Vertical Shift)
Adjust so that the horizontal center line of digital circle
Frequency Modulation Output level pattern is in accord with geometric horizontal center of
the picture tube.
38.9MHz OFF 80dBu
VH (Vertical Height)
Adjust inside of the circle at top and bottom display.
: RF AGC (Auto Gain Control) Adjustment
- 1 -
SC (Vertical "S" Correction) : Deflection Data Adjustment
Adjust so that all distance between each horizontal lines are
to be the same. NOTE: To enter SVC mode, press "SVC" button on the Remote
control or "OK" button on both TV set and the Remote
EW (Horizontal Width) control.
Adjust so that digital circle pattern looks like exact circle.
1. Deflection Adjustment Flow
EP (East-west Parabolar) 1) At deflection adjustment mode, select FUBK signal.
Adjust so that middle portion of the outemost left and right And then, deflection data adjustment OSD displays and at
vertical paralled with vertical lines of the picture tube. the left top of its auto detected field frequency and deflection
adjustment mode are displayed.
EC (East-west Coner) 2) Press "Yellow" button and at deflection adjustment mode
Adjust so that the vertical line at every 4 corners of the (press "DE/FG" button) adjust with 50Hz 16:9 mode and
screen looks like parallel with the vertical lines of the picture the other mode data are stored automatically. After finishing
tube. adjustment at 50Hz 16:9 mode and check the adjusted data
of different mode.
ET (East-west Trapezium) 3) Check the adjusted data changing 50Hz ZOOM1, ZOOM2
Adjust to make the length of top horizontal line same with it and 4:3 mode by pressing "ARC" button and if errors,
of the bottom horizontal line. readjust at each mode.
Position of Blanking Adjustment at 50Hz Wide mode
1) Selection to the Mode of 4:3
Vertical Size
2) Adjust the blanking width control (VR1701) for the same
16:9, 4:3
left and right side of the picture tube.
Top
ZOOM1
ZOOM2
: Screen & White Balance (W/B) Adjustment
NOTE : This adjustment should be preformed after screen
voltage adjustment.
ZOOM1
Bottom
Test Point : Observe Display 16:9, 4:3
ZOOM2
Adjust : Screen Control of FBT
R, G, B Drive level (For SVC Mode)
[ Deflection Adjustment Flowchart
1) Turn the TV set to receive white pattern of PAL standard
Enter SVC Mode
signal.
2) Adjust contrast, Brightness for 45! 1ft-L at the center area of
screen.
Adjust deflection data, 50Hz wide mode
3) Press Yellow button after SVC Mode on remote controller
then you can find "RG---/GG---/BG---" OSD around middle-
left of screen.
4) Set the "GG---" to "GG031". Press ARC button
5) Press CH (UP/DOWN) button you can find "RG---"/"BG---"
OSD around middle-left of screen.
6) Adjust volume up or down button in each status of "RG--- Adjust deflection data
"/"BG---" for X=281! 8, Y=288! 8 with color analyzer (50Hz ZOOM1, 4:3 mode)
Table 1 : White Balance initial data
Adjust position of blanking
Item Adjustment Range of Change Initial Data (50Hz 4:3 Mode)
RG R-Drive 0~63 31 : Press MENU button 2 times
GG G-Drive 0~63 31 Swap into AV mode
BG B-Drive 0~63 31
YD Y-Delay 0~63 * 03 Adjust deflection data
(60Hz 16:9, ZOOM1, ZOOM2, 4:3 mode)
PK Peak White Limit 0~63 * 05
: Press MENU button twice
NOTE : "* " marked items don't need adjust.
Return to TV mode
- 2 -
Table 2 : Deflection initial data : Screen Voltage Adjustment
50Hz DATA 60Hz DATA
Item Test Point : RK (Red Cathod of CPT Board)
16:9 ZOOM 1/2 4:3 16:9 ZOOM 1/2 4:3 Adjust : Screen Control of FBT
HS 18 18 18 26 26 26
1) Turn the TV set to receive digital pattern. (Under the
EW 45 45 32 44 44 31
condition of ARC Mode 16:9 (Wide Mode))
EP 10 10 10 10 10 10 2) Press PSM button on remote controller. (Standard picture)
3) Connect the prove of oscilloscope to the RK (Red Cathod of
EC 20 20 20 20 20 20 CPT Board).
ET 28 16 16 25 16 16 4) Adjust Screen Volume of FBT so that the waveform is the
same as below Fig.3.
VL 35 35 35 35 35 35
Horizontal
VH 18 18 21 20 12 20 FlyBack Time
Black level
SC 26 26 26 22 22 22 160Vp-p
150Vp-p
VS 35 35 35 35 35 35
White level
NOTE : These adjustments are possible with serviceable 1H-LINE GND for dc
remote controller installed SVC button.
If you don't have serviceable remote controller, Fig. 3 : The waveform of RK(Red Cathode) of CPT Board
simultaneously press OK buttons on local control
and on remote controller then TV is changed from
normal mode to SVC mode.
Table 1/2 : Corresponding buttons for each adjustment : Focus Adjustment
NOTE : This adjustment should be performed after warming up
for 10 minutes.
: Audio Data Adjustment
Test Point : Observe display
NOTE : If you press "3" button on the remote controller in SVC Adjust : Focus control of FBT
Mode then you can find On Screen Display as follow
Table 3. [Set condition of the 16:9 (Wide Mode)]
* Never change these data, these are important reference data
for TV.
Table 3 : Audio initial data
Item Adjustment Range of Change Initial Data 1) Tune the TV set to reveive digital pattern.
2) Adjust the under Focus Volume for the best vertical Focus on
SP loud SPK loudness 0~127 000 the center of the screen.
AD Adjust the upper Focus Volume for the best horizontal Focus
3) Ch. Freq. Pattern Signal Function & Check
HP vol 0~127 000 on the center of the screen.
1 PI-41 631~25 PHILIPS NICAM Stereo
SC vol SCART Vol 0~127 030 Table 4 : CH preset Data
2 PI-11 231~25 FUBK Deflection Adjustment
SC pres SC prescale 0~127 059 3 C-36 691~25 ITC
RED
FM pres FM prescale 0~127 019 4 PI-63 807~25 NICAM, TXT
C/HATCH
NC pres NC prescale 0~127 042 5 PI-05 183~25 VHF
PHILIPS
- 3 -
PURITY & CONVERGENCE ADJUSTMENT
Caution:
Convergence and Purity have been factory aligned. Do not 5. Reconnect the internal degaussing coil.
attempt to tamper with these alignments.
However, the effects of adjacent receiver components, or 6. Position the beam bender locking rings at the 9 o'clock
replacement of picture tube or deflection yoke may require the position and the other three pairs of tabs (2,4 and 6 pole
need to readjust purity any convergence. magnets) at the 12 o'clock position.
DEFLECTION YOKE 6-POLE
PURITY &CONVERGENCE 6-POLE
MAGNETS
MAGNES PURITY MAGNET(2-POLE)
MAGNET ASSEMBLY
6-POLE
,,,,
,,,, ,
,,,, ,
,,,, , ,
,,,,
,,,,
,,,, 4-POLE
X-AXIS YOKE MAGNET
,
,,,, , ,,,,
,,,, , ,,,,,
,,,, , ,,,,
,,
,,,, , ,
,,,,
,, , POSITIONING
(L/R PURITY)
RUBBER
WEDGES PURITY MAGNET
4-POLE
GLASS CLOTH TAPE CONVERGENCE MAGNET ASSEMBLY
CONVERGENCE MAGNET ASSEMBLY
Y Purity Adjustment
This procedure DOES NOT apply to bonded yoke and picture 7. Perform the following steps, in the order given, to prepare the
tube assemblies. receiver for the purity adjustment procedure.
The instrument should be at room temperature (60 degrees F or
above) for six (6) hours and be operating at low beam current a. Face the receiver in the "magnetic north" direction.
(dark background) for approximately 20 to 30 minutes before
performing purity adjustments. b. Externally degauss the receiver screen with the television
power turned off.
CAUTION: Do not remove any trim magnets that may be
attached to the bell of the picture tube. c. Turn the television on for approximately 10 seconds to
perform internal degaussing and then turn the TV off.
1. Remove the AC power and disconnect the internal
degaussing coil. d. Unplug the internal degaussing coil. This allows the
thermistor to cool down while you are performing the purity
2. Remove the yoke from the neck of the picture tube. adjustment. DO NOT MOVE THE RECEIVER FROM ITS
"MAGNETIC NORTH" POSITION.
3. If the yoke has the tape version beam bender, remove it and
replace it with a adjustable type beam bender (follow the e. Turn the receiver on and obtain a red raster by increasing
instructions provided with the new beam bender) the red bias control (CW) and decreasing the bias controls
for the remaining two colors (CCW).
4. Replace the yoke on the picture tube neck, temporarily
remove the three (3) rubber wedges from the bell of the f. Attach two round magnets on the picture tube screen at 3
picture tube and then slide the yoke completely forward. o'clock and 9 o'clock positions, approximately one (1) inch
from the edge of the mask (use double-sided tape).
- 4 -
1.ADJUST YOKE Z-AXIS FIRST 2 .ADJUST BEAM BENDER 2 POLE
TO GET EQUAL BLUE MAGNET TO GET FOUR EQUAL
COLOR CIRCLES COLOR CIRCLES
MAGNETS
RED RED
8. Referring to above, perform the following two steps: 6. Reconnect the internal degaussing coil and apply AC power.
a. Adjust the yoke Z-axis to obtain equal blue circles.
b. Adjust the appropriate beam bender tabs to obtain correct 7. Turn the receiver on for 10 seconds to perform internal
purity (four equal circles). degaussing and then turn the receiver off again.
9. After correct purity is set, tighten the yoke clamp screw and 8. Unplug the internal degaussing-coil.
remove the two screen magnets.
9. Turn on the receiver, connect a signal generator to the VHF
10. Remove the AC power and rotate the receiver 180 degrees antenna terminal and apply a crosshatch signal.
(facing "magnetic south").
Caution: During the convergence adjustment procedure, be
11. Reconnect the internal degaussing coil. very careful not to disturb the purity adjustment tabs
are accidentally move, purity should be confirmed
12. Turn the receiver on for 10 seconds (make sure the receiver before proceeding with the convergence adjustments.
came on) to perform internal degaussing, and then turn the
receiver off. Note: Make sure the focus is set correctly on this instrument
before proceeding with the following adjustment.
13. Unplug the internal degaussing coil.
10. Converge the red and blue vertical lines to the green vertical
14. Turn on the receiver and check the purity by holding one (1) line at the center of the screen by performing the following
round magnet at the 3 o'clock and a second round magnet at steps (below TABLE).
9 o'clock position. If purity is not satisfactory, repeat steps 8 a. Carefully rotate both tabs of the 4-pole ring magnet
through 14. simultaneously in opposite directions from the 12 o'clock
position to converge the red and blue vertical lines.
15. Turn off the receiver and reconnect the internal degaussing b. Carefully rotate both tabs of the 6-pole ring magnet
coil. simultaneously in opposite directions form the 12 o'clock
position to converge the red and blue (now purple)
vertical lines with the green vertical line.
Y Convergence Adjustment
11. Converge the red and blue horizontal with the green line at
Caution: This procedure DOES NOT apply to bonded yoke and the center of the screen by performing the following steps.
picture tube assemblies. (below TABLE)
Do not use screen magnets during this adjustment a. Carefully rotate both tabs of the 4-pole ring magnet
procedure. Use of screen magnets will cause an simultaneously in the same direction (keep the spacing
incorrect display. between the two tabs the same) to converge the red and
blue horizontal lines.
1. Remove AC power and disconnect the internal degaussing b. Carefully rotate both tabs of the 6-pole ring magnet
coil. simultaneously in same direction (keep the spacing
between the two tabs the same) to converge the red and
2. Apply AC Power and set the brightness to the Picture Reset blue (now purple) horizontal lines with the green
condition. Set the Color control to minimum. horizontal line.
c. Secure the tabs previsouly adjusted by locking them in
3. Apply 8V to the pin42 of IC501. place with the locking tabs on the beam bender.
4. Adjust the Red, Green and Blue Bias controls to get a dim
white line.
5. Remove the AC power and 8V from the pin42 of IC501.
- 5 -
RING ROTATION DIRECTION MOVEMENT OF RED
PAIRS OF BOTH TABS AND BLUE BEAMS
B B
OPPOSITE OR
R R
4
POLE
SAME B R OR B R
B B
OPPOSITE OR
R R
6
POLE
SAME B R OR B R
UP/DOWN ROCKING OF THE YOKE LEFT/RIGHT ROCKING OF THE YOKE
UP/DOWN ROCKING OF THE YOKE
CAUSES OPPOSITE ROTATION OF RED CAUSES OPPOSITE SIZE CHANGE YOKE
LEET/RIGHT ROCKING OF THE OF THE
AND BLUEOPPOSITE ROTATION OF RED
CAUSES RASTERS RED AND BLUE RASTERS CHANGE OF
CAUSES OPPOSITE SIZE
AND BLUE RASTERS THE RED AND BLUE RASTERS
GREEN
GREEN
ADJUSTMENT
VIEWING ADJUSTMENT RED
AREA BLUE RED VIEWING
AREA
RED
GREEN RED BLUE
BLUE RED
GREEN
RED BLUE
TV
SCREEN
GREEN
12. While watching the 6 o'clock positions on the screen, rock the 17. Temporarily place a rubber wedge at the 5 o'clock and 7
front of the yoke in a vertical (up/down) direction to converge o'clock positions to hold the horizontal position of the yoke.
the red and blue vertical lines. (Fig upper left) 18. Check the 3 o'clock and 9 o'clock areas to confirm that the
13. Temporarily place a rubber wedge at the 12 o'clock position red and blue vertical lines are converged. If the lines are not
to hold the vertical position or the yoke. converged, slightly offset the horizontal tilt of the yoke (move
14. Check the 3 o'clock and 9 o'clock areas to confirm that the red the temporary rubber wedges if necessary) to equally
and blue horizontal lines are converged. balance the convergence error of the horizontal lines at 6
If the lines are not converged, slightly offset the vertical tilt of the o'clock and 12 o'clock and the vertical lines at 3 o'clock and 9
yoke (move the rubber wedge if necessary) to equally balance the o'clock.
convergence error of the horizontal lines at 3 o'clock and 9 o'clock 19. Using a round magnet confirm purity at the center, right and
and the vertical lines at 6 o'clock and 12 o'clock. left sides and corners. See Purity Adjustment Procedure.
15. Place a 1.5 inch piece of glass tape over the rubber foot at 20. Reconfirm convergence and apply a 1.5 inch piece of glass
the rear of the 12 o'clock wedge. tape over the rubber foot at the rear of the 5 o'clock and the 7
16. While watching the 6 o'clock and 12 o'clock areas of the o'clock wedges.
screen, rock the front of the yoke in the horizontal (left to
right) motion to converge the red and blue horizontal lines.
(Fig. upper right)
- 6 -
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