LCD TV
HLT-1751
HLT-2051
Attention: This service manual is only for service personnel to take reference with. Before servicing
please read the following points carefully.
Safety instructions
1 Instructions
1.1 Be sure to switch off the power supply before replacing or welding any components or
inserting/plugging in connection wire
1.2
Anti static measures to be taken (throughout the entire production process!):
1.2.1 Do not touch here and there by hand at will;
1.2.2 Be sure to use anti static electric iron;
1.2.3 It’s a must for the welder to wear anti static gloves.
1.3 Please refer to the detailed list before replacing components that have special safety
requirements. Do not change the specs and type at will.
2 Points for attention in servicing of LCD
2.1 Screens are different from one model to another and therefore not interchangeable. Be
sure to use the screen of the original model for replacement.
2.2 The operation voltage of LCD screen is 700-825V. Be sure to take proper measures in
protecting yourself and the machine when testing the system in the course of normal
operation or right after the power is switched off. Please do not touch the circuit or the
metal part of the module that is in operation mode.
Relevant operation is possible only one minute after the power is switched off.
2.3 Do not use any adapter that is not identical with the TV set. Otherwise it will cause fire
or damage to the set.
2.4 Never operate the set or do any installation work in bad environment such as wet
bathroom, laundry, kitchen,or nearby fire source, heating equipment and devices or
exposure to sunlight etc. Otherwise bad effect will result.
2.5 If any foreign substance such as water, liquid, metal slices or other matters happens
to fall into the module, be sure to cut the power off immediately and do not move
anything on the module lest it should cause fire or electric shock due to contact with
the high voltage or short circuit.
2.6 Should there be smoke, abnormal smell or sound from the module, please shut the
power off at once. Likewise, if the screen is not working after the power is on or in the
course of operation, the power must be cut off immediately and no more operation is
allowed under the same condition.
2.7 Do not pull out or plug in the connection wire when the module is in operation or just
after the power is off because in this case relatively high voltage still remains in the
capacitor of the driving circuit.Please wait at least one minute before the pulling out or
plugging in the connection wire.
2.8 When operating or installing LCD please don’t subject the LCD components to bending,
twisting or extrusion, collision lest mishap should result.
1
2.9 As most of the circuitry in LCD TV set is composed of CMOS integrated circuits, it’s
necessary to pay attention to anti statics. Before servicing LCD TV make sure to take
anti static measure and ensure full grounding for all the parts that have to be grounded.
2.10 There are lots of connection wires between parts behind the LCD screen. When
servicing or moving the set please take care not to touch or scratch them. Once they
are damaged the screen would be unable to work and no way to get it repaired.
2.11 Special care must be taken in transporting or handling it. Exquisite shock vibration
may lead to breakage of screen glass or damage to driving circuit.
Therefore it must be packed in a strong case before the transportation or handling.
2.12 For the storage make sure to put it in a place where the environment can be controlled
so as to prevent the temperature and humidity from exceeding the limits as specified in
the manual. For prolonged storage, it is necessary to house it in an anti-moisture bag
and put them altogether in one place. The ambient conditions are tabulated as follows:
Temperature
humidity
Scope for operation
0—+50
C
Scope for storage
-20—+60
Scope for operation
20%—85%
Scope for storage
10%—90%
C
2.13 Display of a fixed picture for a long time may result in appearance of picture residue on
the screen, as commmonly called “ghost shadow”. The extent of the residual picture
varies with the maker of LCD screen. This phenonmenon doesn’t represent failure.
This “ghost shadow” may remain in the picture for a period of time (several
minutes).But when operating it please avoid displaying still picture in high brightness
for a long time.
3. Points for attention during installation
3.1 The front panel of LCD screen is of glass. Wheng installing it please make sure to put it
in place.
3.2 For service or instatallation it’s necessary to use specified screw lest it should damage
the screen.
3.3 Be sure to take anti dust measures. Any foreign substance that happens to fall down
between the screen and the glass will affect the receiving and viewing effect
3.4 When dismantling or mounting the protective partition plate that is used for anti vibration
and insulation please take care to keep it in intactness so as to avoid hidden trouble.
3.5 Be sure to protect the cabinet from damage or scratch during service, dismantling or
mounting.
Instructions on adjusting and testing
1. Flow process of adjustment and calibration
For flow process of adjustment and calibration, see Fig. 1
2
Fig. 1
Check if N4, N20, N303, N302 has been
FLASH written.
Produce main board, TV board on line
Adjust TV board
Check main board
Check TV board
Combined test for general assembly
Connect to central signal source, check if various TV functions
(station skipping, modulate quantity control etc), check if the output
of earphone and speaker are normal
Input SCART/AV/S signal, check different
functions of SCART/AV/S terminals
Input TV/AV/ S terminal/SCART/VGA signals, select
separately SCART OUTPUT state to be TV or
MONITOR, check if the function of SCART OUTPUT
is normal
Input VGA signal and check if display is normal in the state
of PC and various functions (analog quantity control,
line/field center etc.)
Check accessories and then packing
Figure 1. Flow process of adjustment and calibration
3
2.Adjustment and calibration deacription
2.1 Method to enter factory menu
Push MUTE-MENU-OK-SLEEP key in turn at the interval of 1 second
2.2 Adjustment and calibration equipment
Digital multi-meter, signal generator (with SCART/RGB signal output), oscillograph,
PC set ( preset the program of flash written), K7253(VGA signal generator), CA210
(LCD white balancer) DVD displayer, TV with SCART connector 1 set, IF signal
generator
2.3 Written program
Writing the memory unit N4, N20, N303, N302
2.4 Main board adjustment and calibration
a) Main board X501 Connect infra-red receiving board (as per connect diagram),
insert the output plug of power supply adapter(
FSP060-1AD103 for 17,20’) into X1, when the indication lamp of infra-red receiving
board should be in red
b) Connect PC set. Run FLASH N20 upgrade program, push POWER key on the
remote control set, when the indication lamp of infra-red receiving board should be in
red
c) About 4 minutes later, indication lamp of infra-red receiving board turns to
yellow/blue (HLT-1751/HLT-2051), measure L102 PIN2 5.0 V,L107 PIN2 3.3
V, N10 PIN2 1.8 V, and N12 PIN2 1.8 V.
d) Write DDC program
2.4 TV board adjustment
2.5.1 IF adjustment
a) Input DV 5V into TP2, input 12V to TP6, Input 5V to TP4 and input 0V to TP5,
monitor voltage of TP3, input 38.9 MHz signal to TP1, and use a non-inductance screw
driver to adjust IFT L207 so that TP3 voltage is 1.65V
b) Input DC 5V into TP2, input 12V to TP6, Input 0V to TP4 and input 5V to TP5,
monitor voltage of TP3, input 33.9 MHz signal to TP1, adjust potential meter RP202 to
set TP3 voltage to 1.65V.
c) Connect IF line of tuner, control line L and L’: three disconnected points in total.
2.5.2 Connection of the complete set
Connect main board, TV board, infra-red receiving board (as per connect diagram),
push POWER key on the remoter control set, when the indication lamp of infra-red
receiving board is in yellow/blue (HLT-1751/HLT-2051),measure PIN2 of
N301to be 3.3 V on TV board, one end of SMT conductance L632 to be 5V, another
end of SMT conductance L632 to be 12V.
2.5.3 AGC Adjustment
Receive D-8 signal of 60 db, measure the voltage of positive pole of D201 with DC
potential meter.
Adjust potential meter RP201 to make reading of potential meter just decrease below
4.0V.Input 100db from antenna, the picture should not appear non-synchronized and
distorted, input weak signal of 35 dB--40 dB, color should not disappear, picture
synchronizes, normal sound.
2.6 White balance adjustment ( Use LCD special white balancer CA210,K7253 signal
4
generator)
a) Assembly complete set;
b) Enter factory menu, realize “PW1306 reset”, adjust background brightness to be
maximum;
c) Quit factory menu, enter D_SUB channel, input 60 HZ “pane
signal”(C_Hat_16x12(W)),to VGA terminal. Thus the discrimination rate should be the
best discrimination rate for the LCD screen, see table 1, enter user menu, adjust
brightness to 50, contrast to 50 adjust line center, field and center to make the picture
location to be correct.
d) Input “16 grades of grey degree” signal (Gray(H)-16), enter factory menu, realize
AQC calibration”
e) Quit factory menu, input “8 grey degree” signal ( Gray(H)-8 ), enter user menu,
adjust brightness and contrast, measure sixth degree with CA-210, make Y to 180
cd/m2 , enter factory menu, ,fix green to be 50,adjust red, blue to make
x=284,y=299.(This procedure may not be taken now)
f) Enter AV mode, input “8 grey degree” signal, adjust tint to 0, adjust brightness and
contrast, measure sixth degree with CA-210, make Y to 180 cd/m2 , enter factory
menu, ,fix green to be 50,adjust red, blue to make x=284,y=299.
Notice: For the best discrimination rate of LCD screen, see table 1.
Table 1:LCD resolution of best
Screen size
Factory
LCD resolution of best
Samsung
15”
AU
1024x768
Sanyo
CPT
17”
Samsung
1280x1024
AU
AU
20”
800x600
Chimei
640x480
LG
3. Functional Inspection
3.1. ITV connector
Connect central signal source to RF connector. Enter the search menu--auto
search, check if there is station skipping. Check semi-auto search, see if micro
adjustment is normal, check output of earphone and speaker is normal, picture is
normal.
3.2 SCART/AV/S inut termianl
Separately input signal of SCART/AV/S terminal, check picture and sound if they
are normal.
3.3 AUDIO OUT termianl/ VIDEO OUT terminal
5
Input signal separately to TV/SCART/AV/S terminal, connect AUDIO/VIDEO OUT
terminal to monitor, check the output sound of AUDIO OUT is normal, and output
picture of VIDEO OUT is normal. (HLT-2051)
3.4 SCART connector
3.4.1 Inspection of connector content of SCART OUTPUT
Input signal to different TV/SCART/AV/S/VGA terminals, connect SCART
connector to TV as monitor. Select SCART OUTPUT item of menu to TV, check output
of picture and sound if they are all TV picture and sound, and if they are normal; select
SCART OUTPUT item of menu to MINITOR, check picture and sound if they are
current picture and sound of signal (Under VGA state, switch to formal VGA) and
check if they are normal.
(* Note: For the TV sets produced in the initial stage the picture is colorless for the signal
output from AV OUTPUT,SCART OUTPUT under S-terminal)
3.4.2 inspection of special function of SCART INPUT
a) After power supply on, input SCART to signal generator, the set should
automatically switch to AV1or AV1 RGB state.
b) SCART signal generator outputs CVBS signal (color bar + multi-wave group ),
observe if the picture of the set is normal. The normal screen should be AV1: change
SCART signal to RGB format, the normal screen should be AV1 RGB.
c) Disconnect SCART signal, the set could come back to current TV state.
(Note: This special function is not applicable to VGA)
3.5
VGA connector
Input VGA signal (K7253 signal generator), input different VGA format signal listed
in table 2, after completion of the auto calibration, check the picture and sound if they
are normal. If there is interfere in picture, push the auto-adjustment key on the remote
control set one more time, check if the display is normal.
3.6 Factory preset
Enter factory menu, perform factory presetting under TV state.
3.7 Packing for factory outgoing
Check accessory, then pack.
Table 2.VGA format signal
screen size
15”
17”
resolution
Image clock
H-SYNC
V-SYNC
(MHz)
(kHz)
(Hz)
640x480 @ 60
25.175
31.469
59.900
720x400 @ 70
28.322
31.469
70.086
800x600 @ 60
40.000
37.879
60.317
1024x768 @ 60
65.000
48.363
60.004
640x480 @ 75
31.500
37.500
75.000
800x600 @ 75
49.500
46.875
75.000
1024x768 @ 75
78.750
60.023
75.029
640x480 @ 60
25.175
31.469
59.900
720x400 @ 70
28.322
31.469
70.086
800x600 @ 60
40.000
37.879
60.317
1024x768 @ 60
65.000
48.363
60.004
6
remark
640x480 @ 75
31.500
37.500
75.000
800x600 @ 75
49.500
46.875
75.000
1024x768 @ 75
78.750
60.023
75.029
1280x1024@60
108
63.981
60.2
1280x1024@75
135
79.976
75.025
640x480 @ 60
25.175
31.469
59.900
720x400 @ 70
28.322
31.469
70.086
800x600 @ 60
40.000
37.879
60.317
640x480 @ 75
31.500
37.500
75.000
800x600 @ 75
49.500
46.875
75.000
20”
CMOscreen
nonsupport
CMOscreen
nonsupport
Trouble shooting
Before servicing please check to find the possible causes of the troubles according to the
table below.
1.Antenna:
Picture is out of focus or jumping
Bad status in signal receiving
Maybe broadcast signal itself is not good
Check if the outdoor antenna is disconnected.
Check if the antenna is correctly oriented.
Fringe in picture
Check if the antenna is correctly oriented.
Maybe there is electric wave reflected from hilltop or building.
Picture is interfered
shaped bright spots
by
stripe
Possibly due to interference from automobile, train, high
voltage transmission line, neon lamp etc.
Maybe there is interference between antenna and power
supply line. Please try to separate them in a longer distance.
There appear streaks or light color
on the screen
Check if interfered by other equipment and if interfered
possibly by the equipment like transmitting antenna, non
professional radio station and cellular phone.
7
2.TV set:
Symptoms
Possible cause
Unable to switch the power on
Check to see if the power plug has been inserted properly into
the socket.
No picture and sound
Check to see if the power supply of liquid crystal TV has been
switched on. (as can be indicated by the red LED at the front
of the TV set)
See if it’s receiving the signal that is transmitted
from other
source than the station
Check if it’s connected to the wrong terminal or if the input
mode is correct.
Check if the signal cable connection between video frequency
source and the liquid crystal TV set is correct.
Deterioration of color phase or color
Check if all the picture setups have been corrected.
tone
Screen position or size is not proper
Check is the screen position and size is correctly set up.
Picture is twisted and deformed
Check to see if the picture-frame ratio is properly set up.
Picture color changed or colorless
Check the “Component” or”RGB”settings of the
liquid crystal
TV set and make proper adjustment according to the signal
types.
Picture too bright and there is
Check if the contrast setting is too high.
distortion in the brightest area
Possibly the output quality of DVD broadcaster is set too high.
It maybe also due to improper terminal connection of the video
frequency signal in a certain position of the system.
Picture is whitish or too bright in the
darkest area of the picture
Check if the setting for the brightness is too high
Possibly the brightness grade of DVD player(broadcaster)is
set too high.
No picture or signal produced from
the
displayer
if
“XXX
in
search”appears.
There
appears
Check if the cable is disconnected.
Check if it’s connected to the proper terminal or if the input
mode is correct.
an
indication
-
“outside the receivable scope)
Check if the TV set can receive input signal. The signal is not
correctly identified and VGA format is beyond the specified
scope.
Remote
control
cannot
work
properly
Check if the batteries are installed in the reverse order.
Check if the battery is effective.
Check the distance or angle from the monitor.
Check if there is any obstruct between the remote control and
the TV set.
Check if the remote control signal- receiving window is
exposed to strong fluorescence.
No picture and sound, but only
hash.
Check if the antenna cable is correctly connected, or if it has
received the video signal correctly.
8
Blur picture
Check if the antenna cable is correctly connected.
Of if it has received the right video signal.
No sound
Check if the “mute” audio frequency setting is selected.
Check if the sound volume is set to minimum.
Make sure the earphone is not connected.
Check if the cable connection is loose.
When playing VHS picture search
tape, there are lines at the top or
bottom of the picture.
When being played or in pause VHS picture search tape
sometimes can’t provide stable picture, which may lead to
incorrect display of the liquid crystal TVIn this case please
press “auto” key on the remote control so as to enable the
liquid crystal TV set to recheck the signal and then to
display correct picture signal
Method of software upgrading
1
2
3
Steps of software upgrading are as follows:
Select a serial connection wire and a VGA connection wire and then connect them by
means of a patch panel;
Use a serial wire to connect the PC to the patch panel and set TV set to off state;
Open the software upgrade file holder and double click
FlashUpgraderNT(use under window 2000/XP/NT)
FlashUpgrader(use under window 98),
The following interfaces will show up after running the program:
9
Based on the computer features, set up the serial port(COM Port). Select corresponding serial port (if
it’s unable to FLASH WRITE, change to another port). Baud is selected to be 115200. Then select
Reset Target After Download. Click FLASH pushbutton, it’s ready to run. For other settings, please
refer to the Fig. Above (already defaulted by the system, normally no need to change).
4 Switch on TV set the FLASH write program begins to run;
5 After FLASH write is over, push button “cancel” will become flash. Then shut the main power supply
and it’s OK just switch it on again.
Note: Do not shut the power off or turn the TV set on during the FLASH write. Otherwise it may
lead to no way for flash to rewrite.
Simple introduction and work principle of HLT-1751/HLT-2051
HLT-2051 multi-media LCD TV broadcast receiver adopts CMO 20.1 inch LCD display
screen as display unit. It has PAL/SECAM B/G,I,D K L L, color system receiving functions
and at the same time with AV input, S-VHS input, PC VGA connector and earphone output
and other signal connectors. The power supply is outer connection of 12V power supply
adaptor
HLT-1751/HLT-2051 multi-media LCD TV broadcast receiver consists of RF, video signal
board assy”, digit picture processing assy’.
RF signal produces picture IF signal and sound IF signal by tuner N201, through Video
and Sound saw filter Z201, Z202, and the signals are sent to Video/Sound(VIF/SIF) multi
systems signal processor of N202 TDA4470 pin6,pin7,and pin1,pin2, for picture and sound
demodulation. The demodulated composite signal, after trapping, is selected by the switch
N202, and then output to N303 and ICVCT3833 for decoding.
The composite video signal is sent through foot 19 of ICN303VCT3833. After
processing there, it is output as analog RGB signal from Pin42, PIN43, PIN44 to digit
10
picture processing assy’. The sound SIF signal is sent to foot 67 of ICN402 MSP3410G for
sound processing. The output signal from Pin28,Pin27 of N401MSP3410G is output to
sound amplification N404TDA7268(20”TPATP1517). After amplification, it is sent to
speaker.
Input signals to main board include RGB signals from RF, video signal assy’, VGA
signal from personal computer. The 2:1 switches ICN5 BA7657F of five routs select R,G,B
signals and then send them to main processor IC PW1306.
PW1306 is a main processing IC built-in type X86 CPU, with outer memory 8M
Flash(N20)and controls the whole system. The input signal from V-port and G-port is
subject to internal arithmetic process and then output in R,G,B of 24 bit TTL to sockets
JP3,JP4. Through connection line the signal is sent to CMO LCD screen port for the
realization of the picture re-display.
Converter DS90C383A/DS90CF383A LVDS converts CMOS/TTL data of 28
digit(DRE<7:0>, DGE<7:0>, DBE<7:0>and LCD timing and control data, FPLINE,
FPFEAME, DRDY)to four groups of LVDS INFORMATION FLOW (Low voltage differential
signal), then send them to the plane displayer for display.
11
IC BLOCK
BA7657F / BA7657S
24
HD 1 input
2
23
HD 2 input
Green 1 input
3
22
HD output
Ground
4
21
Red output
20
VCC
19
Green output
18
Composite video input (Sync on Green)
17
Composite sync output
16
CTL (H: IN1, L: IN2)
15
Blue output
14
VD output
13
VD 2 input
Red 1 input
1
HD Sync signal detector
1
2
1
2
Blue 1 input
5
Ground
6
DET
1
2
Red 2 input
7
Syncsepa
Ground
8
Green 2 input
9
Logic
1
Ground
10
Blue 2 input
11
2
1
2
VD 1 input
12
Clamp
Clamp
Clamp
GAIN
BAIN
SOG
Stripper
Color
Space
Converter
RAIN
FILT
SOGIN
HSYNC,
VSYNC
VYUV(7:0)
VCLK
VPEN
B
G
R
CLK
ADC
A/D
A/D
A/D
PLL
VS
HS
VIDEO
Sync
Processing
RGB
CLK
HS,VS
Data
MUX
IR
Decoder
Memory
Buffer
Processor
Memory
Interface
PWM
RESET
XI
XO
PLL and
Oscillator
OSD
and
Gain
Pow erOn
Reset
Color
Matrix
OSD
Interrupt
Controller
NMI
Display
Timing
Generator
Color
Space
Expander
UART
TxD RxD
PW130 ImageProcessor
Internal Block Diagram
Color
Lookup
Tables
Watchdog and
Timers
Processor ROM/
RAM Interface
A
D
CS
(19:1) (15:0) (1:0)
Microprocessor Bus
16-Bit
Microprocessor
MCLK DCLK UCLK
Scaler
2-Wire
Serial
Figure 1-1 ImageProcessor Block Diagram
Memory In Bus
JTAG Debugger
Reset
Auto Image
Optimization
GPIO
PORTD (7:0)
Memory Out Bus
PortA(7:0)
DVS, DHS,
DEN, DCLK
DGRGB(23:0)
DRGB (23:0)
PW130
TDA4470
ÏÏ
ÏÏ
Block Diagram
L’ switch
Loop
filter
Offset
comp.
(optional)
Ï
VCO
Ï
26
ÏÏ Ï
18
20
0°
90°
FPLL
21
VCO
+
phase shift
ÏÏ
14
Control
ÏÏ
Ï
ÏÏ Ï
ÏÏ
19
AFC
Ï
Ï
Ï
Ï
ÏÏ
Ï
6
VIF
VIF amp
ÏÏ
CBL
Tuner
ÏÏ Ï
13
AGC
(VIF)
Standard
11
10
Take over
point
SIF 2
Ï
Ï
Ï
Ï
Ï
Ï
Ï
ÏÏ
Ï
Tuner
AGC
Supply
FM det.
27
VS
17
CRef
ÏÏ
Intercarrier
(FM / NICAM)
SIF amp
3
2
5
CAGC
Standard
switch
24
1
SIF 1
ÏÏ
Ï
ÏÏ Ï
ÏÏ
23
28
SIF input
switch
Video
Video det.
8
15
AFC
12
7
CAGC
22
AFC
switch
ÏÏ
ÏÏ
ÏÏ
ÏÏ
25
AGC
(SIF)
AM det.
4,9,16
95 10851
Figure 1. Block diagram
AF
(AM)
HIGH
VOLTAGE
HIGH
VOLTAGE
S-video
V
R
L
R
MSP3420G
Audio
L
Serial No. of Parts
15"
17"
20"
Sell area
Europe
Europe
LCD panel
Samsung
335-15012-00
AU
335-17050-00
Chimei
335-2000F-00
Back light board
667-L15H3-14
667-L17H3-14
667-L20H3-14A
High frequency board
667-L15H3S-55
667-L15H3-55
Main board
667-L15H3-01S
adapter
302-L1510-02
antetype
203-L15H30-02
Sell area
Europe
LCD panel
AU335-15112-00
AU335-2000F-00
Back light board
667-L15H3-14A
667-L20H3-14A
High frequency board
667-L15H3S-55
667-L20H3S-55
Main board
667-L15H3-01BS
667-L20H3-01S
adapter
302-L1510-02
antetype
203-L15H30-03
Europe
America
667-L20H3S-55
667-L20H3-01S
302-AD16A-02
Europe
302-AD16A-02
Europe
America
302-ADA6A-02
203-L20H30-02
Identification criteria for the bright spot and dark spot of the LCD screen
Category
Bright
spot
Dark
spots
criteria
Q’ty allowed
Distance between two spots
15"
20"
22"
30"
40"
≤5
≤2
≤5
≤2
≤3
≤2
≤1
≤2
≤1
≤1
Total No.
≤5
≤2
≤5
≤2
≤3
One single
spot
≤6
≤7
≤5
≤4
≤10
Two
neighboring
spots
≤2
≤2
≤2
≤1
≤5
Total No.
≤6
≤7
≤5
≤4
≤10
One single
spot
2 neighboring
spots
Total defected point
≤8
≤7
≤5
≤4
15"
20"
22"
30"
40"
≥15mm
≥15mm
≥10mm
≥5mm
/
Notes:
1. Definition of defected point (bright spot, dark spot): It is identified as a defected point if its
area exceeds 1/2 of a single picture element (R,G,B).
2. Definition of bright spot: It is identified as a bright spot if it is bright in the state of dark field
and its bright size remains unchanged
3. Definition of dark spot: It is identified as a dark spot if it is dark in the state of white field and
its dark size remains unchanged
4. Definition of two neighboring points: Defects of a group of picture elements(RB,RG,GB).
22
Troubleshooting guide
No raster
Does the logo appear on the screen
when turning on the set ?
No
Check whether the adapter
supply 12V power to Digital Board.
Yes
No
Check whether X101 is
properly inserted.
Yes
Check whether there is R.G.B
output at X601 on TV board.
Good
Check U125965V.
No
Check whether FUSE is melted.
No
Good
Check whether U18 pin 63
is high level.
Replace TV board.
Replace adapter.
No
Replace Digital board.
No sound
Check N8 pin 14, 15, 22, 23, 38,
39, 46,47 (these pins should
have 12V power supply)
No
Check L302, X604 pin 5 and pin 6.
Yes
Check N8 pin3, pin 5's input signal.
Yes
Check whether N8 pin 4, 27, 28 are
normal. Pin 4 should be 2.43V,
pin 27 should be 1.46V and
pin 28 should be triangle wave.
No
Check N6 pin 5 and
pin 8 signal.
Yes
Check N8's welding
condition.
No
Check N5 pin 27
and pin 28 signal.
No
Check N5 pin 67 signal.
No
No
Check whether U1 pin 11
have output waveform.
Replace N8.
23
TV board troubleshooting
No picture but have raster.
Measure the waveform of
R.G.B Hors, Vers at X7.
No
Check whether N1 has
5V power supply.
No
Check whether X9 pin 1, pin 2 have
5V power input.
Yes
Measure N1 pin 33, pin 35
waveform.
No
Replace N2
No
Yes
Measure N1 pin 42, pin 44
waveform.
No
Yes
Check V105-V107's
output waveform.
No
Replace V105-V17.
24
Replace N1
HLT-1751
HLT-2051-01
HLT-2051-02
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