LG DI-28Z12 User manual

SERVICE MANUAL
LG DI-28Z12
MODEL

- 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) 1[EA]
2. DC Power Supply
3. Digital Multimeter (volt meter) 2[EA]
4. Oscilloscope 2[EA]
5. White balance meter 1[EA]
: VCO (Voltage Controlled Oscillator) Adjustment
1) Turn on DC power supplies.
2) Adjust Video Detector Coil (L107) for 2.85!0.1Vdc.
NOTE : The condition of signal Generator.
:RF AGC (Auto Gain Control) Adjustment
The RF AGC control (VR101) was aligned at the time of
manufacture for optimum performance over a wide range
conditions. Readjust of VR101 should not be necessary
unless unusual local conditions exists, 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 the VR101 (RF AGC) control to one end of rotation
will usually cause a relatively poor signal to noise ratio;
Adjusting to the jother end of rotation will usually cause a
degradation of over load capabilities resulting in color beats or
adjacent channel reference.
Adjustment (Refer to Table 1)
VL (Vertical Linearity)
Adjust so that the boundary line between upper and lower
half is in accord with vertical blanking line.
VS (Vertical Shift)
Adjust so that the horizontal center line of digital circle
pattern is in accord with geometric horizontal center of
the picture tube.
VH (Vertical Height)
Adjust inside of the circle at top and bottom display.
Test Point : J72
Adjust : L107
Test Point : J189 or Observing Display
Adjust : VR101
ADJUSTMENT
Frequency
38.9MHz
Modulation
OFF
Output level
80dBu
5Vdc
Power
Supply
RF
Signal
generator
38.9MHz
GND
GND
L106
L01
C115(-)
IC102
TDA9815
L107
(VCO ADJ.)
Z101
G3962
Ceramic
CAP.
10000pF
Ceramic
CAP.
10000pF
Multimeter &
oscilloscope
2.85Vdc
IC01
u-COM
J72
34 5
Digital
Multimeter
AGC TP.
J189
Tuner
VR101
(AGC ADJ.)
IF Board
Fig.1 : Connection Diagram of Equipment for VCO Adjustment.
Fig. 2 : Connection Diagram of Equipment for AGC Adjustment.

- 2 -
SC (Vertical “S” Correction)
Adjust so that all distance between each horizontal lines are
to be the same.
EW (Horizontal Width)
Adjust so that digital circle pattern looks like exact circle.
EP (East-west Parabolar)
Adjust so that middle portion of the outemost left and right
vertical paralled with vertical lines of the picture tube.
EC (East-west Coner)
Adjust so that the vertical line at every 4 corners of the
screen looks like parallel with the vertical lines of the picture
tube.
ET (East-west Trapezium)
Adjust to make the length of top horizontal line same with it
of the bottom horizontal line.
Position of Blanking
1) Selection to the Mode of 4:3
2) Adjust the blanking width control (VR1701) for the same
left and right side of the picture tube.
:Screen & White Balance (W/B) Adjustment
NOTE : This adjustment should be preformed after screen
voltage adjustment.
1) Turn the TV set to receive white pattern of PAL standard
signal.
2) Adjust contrast, Brightness for 45!1ft-L at the center area of
screen.
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".
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---
"/"BG---" for X=281!8, Y=288!8 with color analyzer
Table 1 : White Balance initial data
NOTE : "* " marked items don't need adjust.
:Deflection Data Adjustment
NOTE: To enter SVC mode, press "SVC" button on the Remote
control or "OK" button on both TV set and the Remote
control.
1. Deflection Adjustment Flow
1) At deflection adjustment mode, select FUBK signal.
And then, deflection data adjustment OSD displays and at
the left top of its auto detected field frequency and deflection
adjustment mode are displayed.
2) Press "Yellow" button and at deflection adjustment mode
(press "DE/FG" button) adjust with 50Hz 16:9 mode and
the other mode data are stored automatically. After finishing
adjustment at 50Hz 16:9 mode and check the adjusted data
of different mode.
3) Check the adjusted data changing 50Hz ZOOM1, ZOOM2
and 4:3 mode by pressing "ARC" button and if errors,
readjust at each mode.
Adjustment at 50Hz Wide mode
Item
RG
GG
BG
YD
PK
Range of Change
0~63
0~63
0~63
0~63
0~63
Initial Data
31
31
31
* 03
* 05
Adjustment
R-Drive
G-Drive
B-Drive
Y-Delay
Peak White Limit
Test Point : Observe Display
Adjust : Screen Control of FBT
R, G, B Drive level (For SVC Mode)
16:9, 4:3
ZOOM1
ZOOM2
ZOOM1
16:9, 4:3
ZOOM2
Top
Bottom
Vertical Size
[Deflection Adjustment Flowchart
Enter SVC Mode
: Press MENU button 2 times
: Press MENU button twice
Adjust deflection data, 50Hz wide mode
Press ARC button
Adjust position of blanking
(50Hz 4:3 Mode)
Adjust deflection data
(50Hz ZOOM1, 4:3 mode)
Swap into AV mode
Return to TV mode
Adjust deflection data
(60Hz 16:9, ZOOM1, ZOOM2, 4:3 mode)

- 3 -
Table 2 : Deflection initial data
Table 1/2 : Corresponding buttons for each adjustment
:Audio Data Adjustment
NOTE : If you press "3" button on the remote controller in SVC
Mode then you can find On Screen Display as follow
Table 3.
* Never change these data, these are important reference data
for TV.
Table 3 : Audio initial data
:Screen Voltage Adjustment
1) Turn the TV set to receive digital pattern. (Under the
condition of ARC Mode 16:9 (Wide Mode))
2) Press PSM button on remote controller. (Standard picture)
3) Connect the prove of oscilloscope to the RK (Red Cathod of
CPT Board).
4) Adjust Screen Volume of FBT so that the waveform is the
same as below Fig.3.
:Focus Adjustment
NOTE : This adjustment should be performed after warming up
for 10 minutes.
[Set condition of the 16:9 (Wide Mode)]
1) Tune the TV set to reveive digital pattern.
2) Adjust the under Focus Volume for the best vertical Focus on
the center of the screen.
3) Adjust the upper Focus Volume for the best horizontal Focus
on the center of the screen.
Table 4 : CH preset Data
NOTE : These adjustments are possible with serviceable
remote controller installed SVC button.
If you don't have serviceable remote controller,
simultaneously press OK buttons on local control
and on remote controller then TV is changed from
normal mode to SVC mode.
Item
SP loud
HP vol
SC vol
SC pres
FM pres
NC pres
Range of Change
0~127
0~127
0~127
0~127
0~127
0~127
Initial Data
000
000
030
059
019
042
Adjustment
SPK loudness
SCART Vol
SC prescale
FM prescale
NC prescale
AD
1
2
3
4
5
Pattern
PHILIPS
FUBK
RED
C/HATCH
PHILIPS
Signal Function & Check
NICAM Stereo
Deflection Adjustment
ITC
NICAM, TXT
VHF
Ch.
PI-41
PI-11
C-36
PI-63
PI-05
Freq.
631~25
231~25
691~25
807~25
183~25
Test Point : RK (Red Cathod of CPT Board)
Adjust : Screen Control of FBT
Test Point : Observe display
Adjust : Focus control of FBT
Horizontal
FlyBack Time Black level
White level
GND for dc
1H-LINE
160Vp-p
Fig. 3 : The waveform of RK(Red Cathode) of CPT Board
150Vp-p
HS
EW
EP
EC
ET
VL
VH
SC
VS
Item 50Hz DATA 60Hz DATA
16:9
18
45
10
20
28
35
18
26
35
ZOOM 1/2
18
45
10
20
16
35
18
26
35
4:3
18
32
10
20
16
35
21
26
35
16:9
26
44
10
20
25
35
20
22
35
ZOOM 1/2
26
44
10
20
16
35
12
22
35
4:3
26
31
10
20
16
35
20
22
35

- 4 -
PURITY & CONVERGENCE ADJUSTMENT
Caution:
Convergence and Purity have been factory aligned. Do not
attempt to tamper with these alignments.
However, the effects of adjacent receiver components, or
replacement of picture tube or deflection yoke may require the
need to readjust purity any convergence.
Y Purity Adjustment
This procedure DOES NOT apply to bonded yoke and picture
tube assemblies.
The instrument should be at room temperature (60 degrees F or
above) for six (6) hours and be operating at low beam current
(dark background) for approximately 20 to 30 minutes before
performing purity adjustments.
CAUTION: Do not remove any trim magnets that may be
attached to the bell of the picture tube.
1. Remove the AC power and disconnect the internal
degaussing coil.
2. Remove the yoke from the neck of the picture tube.
3. If the yoke has the tape version beam bender, remove it and
replace it with a adjustable type beam bender (follow the
instructions provided with the new beam bender)
4. Replace the yoke on the picture tube neck, temporarily
remove the three (3) rubber wedges from the bell of the
picture tube and then slide the yoke completely forward.
5. Reconnect the internal degaussing coil.
6. Position the beam bender locking rings at the 9 o'clock
position and the other three pairs of tabs (2,4 and 6 pole
magnets) at the 12 o'clock position.
7. Perform the following steps, in the order given, to prepare the
receiver for the purity adjustment procedure.
a. Face the receiver in the "magnetic north" direction.
b. Externally degauss the receiver screen with the television
power turned off.
c. Turn the television on for approximately 10 seconds to
perform internal degaussing and then turn the TV off.
d. Unplug the internal degaussing coil. This allows the
thermistor to cool down while you are performing the purity
adjustment. DO NOT MOVE THE RECEIVER FROM ITS
"MAGNETIC NORTH" POSITION.
e. Turn the receiver on and obtain a red raster by increasing
the red bias control (CW) and decreasing the bias controls
for the remaining two colors (CCW).
f. Attach two round magnets on the picture tube screen at 3
o'clock and 9 o'clock positions, approximately one (1) inch
from the edge of the mask (use double-sided tape).
DEFLECTION YOKE
PURITY &CONVERGENCE
MAGNET ASSEMBLY
RUBBER
WEDGES
GLASS CLOTH TAPE
,,,,
,,,,
,,,,,
,,,,
,,,,
,,
,,
,,,
,,,
,,
,,,,,
,,,,,
,,,,,
,,,,,,
,,,,,
,,,,,
,,,,,
,,,,,
,,
PURITY MAGNET
6-POLE
4-POLE
4-POLE
MAGNET
CONVERGENCE MAGNET ASSEMBLY
6-POLE
MAGNES PURITY MAGNET(2-POLE)
X-AXIS YOKE
POSITIONING
(L/R PURITY)
6-POLE
MAGNETS
CONVERGENCE MAGNET ASSEMBLY

- 5 -
8. Referring to above, perform the following two steps:
a. Adjust the yoke Z-axis to obtain equal blue circles.
b. Adjust the appropriate beam bender tabs to obtain correct
purity (four equal circles).
9. After correct purity is set, tighten the yoke clamp screw and
remove the two screen magnets.
10. Remove the AC power and rotate the receiver 180 degrees
(facing "magnetic south").
11. Reconnect the internal degaussing coil.
12. Turn the receiver on for 10 seconds (make sure the receiver
came on) to perform internal degaussing, and then turn the
receiver off.
13. Unplug the internal degaussing coil.
14. Turn on the receiver and check the purity by holding one (1)
round magnet at the 3 o'clock and a second round magnet at
9 o'clock position. If purity is not satisfactory, repeat steps 8
through 14.
15. Turn off the receiver and reconnect the internal degaussing
coil.
Y Convergence Adjustment
Caution: This procedure DOES NOT apply to bonded yoke and
picture tube assemblies.
Do not use screen magnets during this adjustment
procedure. Use of screen magnets will cause an
incorrect display.
1. Remove AC power and disconnect the internal degaussing
coil.
2. Apply AC Power and set the brightness to the Picture Reset
condition. Set the Color control to minimum.
3. Apply 8V to the pin42 of IC501.
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.
6. Reconnect the internal degaussing coil and apply AC power.
7. Turn the receiver on for 10 seconds to perform internal
degaussing and then turn the receiver off again.
8. Unplug the internal degaussing-coil.
9. Turn on the receiver, connect a signal generator to the VHF
antenna terminal and apply a crosshatch signal.
Caution: During the convergence adjustment procedure, be
very careful not to disturb the purity adjustment tabs
are accidentally move, purity should be confirmed
before proceeding with the convergence adjustments.
Note: Make sure the focus is set correctly on this instrument
before proceeding with the following adjustment.
10. Converge the red and blue vertical lines to the green vertical
line at the center of the screen by performing the following
steps (below TABLE).
a. Carefully rotate both tabs of the 4-pole ring magnet
simultaneously in opposite directions from the 12 o'clock
position to converge the red and blue vertical lines.
b. Carefully rotate both tabs of the 6-pole ring magnet
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.
11. Converge the red and blue horizontal with the green line at
the center of the screen by performing the following steps.
(below TABLE)
a. Carefully rotate both tabs of the 4-pole ring magnet
simultaneously in the same direction (keep the spacing
between the two tabs the same) to converge the red and
blue horizontal lines.
b. Carefully rotate both tabs of the 6-pole ring magnet
simultaneously in same direction (keep the spacing
between the two tabs the same) to converge the red and
blue (now purple) horizontal lines with the green
horizontal line.
c. Secure the tabs previsouly adjusted by locking them in
place with the locking tabs on the beam bender.
MAGNETS
RED RED
1.ADJUST YOKE Z-AXIS FIRST
TO GET EQUAL BLUE
COLOR CIRCLES
2 .ADJUST BEAM BENDER 2 POLE
MAGNET TO GET FOUR EQUAL
COLOR CIRCLES

- 6 -
RING
PAIRS
4
POLE
ROTATION DIRECTION
OF BOTH TABS
OPPOSITE
SAME
OPPOSITE
SAME
MOVEMENT OF RED
AND BLUE BEAMS
B B
RR OR
OR
B R B R
OR
B
R
B
R
B R OR BR
6
POLE
12. While watching the 6 o'clock positions on the screen, rock the
front of the yoke in a vertical (up/down) direction to converge
the red and blue vertical lines. (Fig upper left)
13. Temporarily place a rubber wedge at the 12 o'clock position
to hold the vertical position or the yoke.
14.
Check the 3 o'clock and 9 o'clock areas to confirm that the red
and blue horizontal lines are converged.
If the lines are not converged, slightly offset the vertical tilt of the
yoke (move the rubber wedge if necessary) to equally balance the
convergence error of the horizontal lines at 3 o'clock and 9 o'clock
and the vertical lines at 6 o'clock and 12 o'clock.
15. Place a 1.5 inch piece of glass tape over the rubber foot at
the rear of the 12 o'clock wedge.
16. While watching the 6 o'clock and 12 o'clock areas of the
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)
17. Temporarily place a rubber wedge at the 5 o'clock and 7
o'clock positions to hold the horizontal position of the yoke.
18. Check the 3 o'clock and 9 o'clock areas to confirm that the
red and blue vertical lines are converged. If the lines are not
converged, slightly offset the horizontal tilt of the yoke (move
the temporary rubber wedges if necessary) to equally
balance the convergence error of the horizontal lines at 6
o'clock and 12 o'clock and the vertical lines at 3 o'clock and 9
o'clock.
19. Using a round magnet confirm purity at the center, right and
left sides and corners. See Purity Adjustment Procedure.
20. Reconfirm convergence and apply a 1.5 inch piece of glass
tape over the rubber foot at the rear of the 5 o'clock and the 7
o'clock wedges.
RED
BLUE
RED BLUE
BLUE
RED
GREEN
GREEN
BLUE RED
GREEN
GREEN
ADJUSTMENT
VIEWING
AREA
UP/DOWN ROCKING OF THE YOKE
CAUSES OPPOSITE ROTATION OF RED
AND BLUE RASTERS
ADJUSTMENT
VIEWING
AREA RED
RED
GREEN
TV
SCREEN
LEET/RIGHT ROCKING OF THE YOKE
CAUSES OPPOSITE SIZE CHANGE OF
THE RED AND BLUE RASTERS
UP/DOWN ROCKING OF THE YOKE
CAUSES OPPOSITE ROTATION OF RED
AND BLUE RASTERS
LEFT/RIGHT ROCKING OF THE YOKE
CAUSES OPPOSITE SIZE CHANGE OF THE
RED AND BLUE RASTERS

- 1 -
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,,,
510
400
943
913
112
102
170 150
153
121
120
912
922
300
174
530
501
520
550
540
590 521
561
563
560
570
580
562
320
331
315
330
EXPLODED VIEW

102 341-919C HOLDER,D-COIL
112 6341V28001A BARE CPT ASSY,W66QBD590X 0.4GGAUS
120 6400VF5001C SPEAKER,MID-RANGE 8 OHM 5/12W
121 120-C76F SPEAKER,TWEETER 8OHM 10/20
150 150-201L COIL,DEGAUSSING
153 6150Z-5031F DY DW28SLNO1
170 170-797W LEAD SET,CPT EARTH
174 174-225N POWER CORD
300 3091V00153A CABINET ASSY
315 315-739C DOOR,MAIN 1
320 320-075B SPRING,KNOB
330 5020V00277A BUTTON,POWER
331 441-754A BUTTON,DOOR OPEN
400 3809V00114A BACK COVER ASSY
501 312-391B FRAME,MAIN
510 6871VSN089A PWB ASSY,CPT
520 6871VMN094A PWB ASSY,MAIN 1
521 401-745E BOARD ASSY,AV
530 6871VDN007A PWB ASSY,DEF+POWER(MAIN2)
540 109-548E PCB ASSY,SHARP & BLANK
550 6871VSN088A PWB ASSY,AUDIO
560 6871VSN090A PWB ASSY,LED DISPLAY
561 2075V00001A INTERNET SET TOP BOX
562 6718V00001A CARD PCMCIA,SMART CARD
563 4810V00120A BRACKET,MAIN 1
570 6871VSN091A PWB ASSY,KEY
580 6871VSN092A PWB ASSY,POWER
590 6871VSN087A PWB ASSY,AV
912 332-240A SCREW ASSY,’P’TYPE+WASHER
913 332-229D SCREW ASSY,HEXAGON HEAD
922 1PTF0402816 SCREW,TRUSS HEAD D4 L12
943 1PTF0403116 SCREW,TRUSS HEAD D4 L16
- 2 -
EXPLODED VIEW PARTS LIST
LOCA. NO PART NO DESCRIPTIONS
The components identified by mark are
critical for safety.
Replace only with part number specified.

TUNER(FS)
IC101, VIF/SIF
TDA9815
IF AGC
IC601
SOUND
PROCESSOR
MSP3410
CTI
TDA4566
TDA8376
VIDEO
CHROMA
DEFLECTION
IC1601
SOUND AMP
LA4282
VIDEO S/W
TEA6415
CPT
A/V2
VIDEO AMP
TEA6108
SVM
CPT/VM ASSY
SHARNESS
AN5342K R.G.B.
VM
L
R
SCART1
SKY-OUT
VM
IH DELAY
TDA4665
H-BLANKING
MC14538BCP
STR-6709
IC801 SMPS
TRANS
FBT
FRONT A/V,S-VIDEO
R.G.B.
Y
U.V
AC IN
MAIN S/W H-DRIVE
H-OUT
V-OUT
LA7845
MAIN2 ASSY(POWER& DEFLECTION)
POWER-IN ASSY
GM71C4256
SDA5273
SDB8032
74HC373
27C512
MEGATEXT
PART
R.G.B.
STB
U-COM
CXP EEPROM
24C16
CVBS(MONITOR)
U-COM
INTER
-FACE
R.G.B.
CVBS(RF)
CVBS(MONITOR)
CVBS(A/V1)
CVBS
U.V
Y
RGB S/W
TEA5114
R.G.B.
R.G.B.
AUDIO
L,R
R,G,B,
CVBS1
CVBS2
R.G.B.
CVBS
(STB)