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LCD TELEVISION
LC-26HU56S
CONTENTS
Safety precautions...................................................................................... 1
Alignment instructions ................................................................................ 3
Method of software upgrading....................................................................... 6
Working principle analysis of the unit...............................................................12
Block diagram.............................................................................................13
IC block diagram.........................................................................................14
Wiring diagram ........................................................................................ 18
Troubleshooting guide ................................................................................ 19
Schematic diagram.................................................................................... 24
APPENDIX-A: Assembly list
APPENDIX-B: Exploded View
Attention: This service manual is only for service personnel to take reference with. Before
servicing please read the following points carefully.
Safety precautions
1. Instructions
Be sure to switch off the power supply before replacing or welding any components or
inserting/plugging in connection wire. Anti static measures must be taken (throughout the entire
manufacturing process!):
a) Do not touch here and there by hand at will;
b) Be sure to use anti static electric iron;
c) It's a must for the welder to wear anti static gloves.
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 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.
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.
1
If the connection wires, connections or components fixed by the thermotropic glue need to
disengage when service, please soak the thermotropic glue into the alcohol and then pull them out
in case of damage.
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 Scope for operation 0 ~ +50 oC
Scope for storage -20 ~ +60 oC
Humidity Scope for operation 20% ~ 85%
Scope for storage 10% ~ 90%
2.13 Display of a fixed picture for a long time may result in appearance of picture residue on the
screen, as commonly called "ghost shadow". The extent of the residual picture varies with the
maker of LCD screen. This phenomenon 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. When installing it please make sure to put it in place.
3.2 For service or installation 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.
2
Alignment instructions
1. Test equipment
PM5518 (video signal generator)
VG-848 (VGA, HDMI signal generator)
VG-849 (digital video signal generator)
CA210 (color analyzer)
2. Power test
Connect main board, power board and IR board according to the wiring diagram, connect the power
and press "standby" to turn on the TV.
Measure the pin voltage of XS15, the data is shown in table1:
Table1 voltage data of XS15
Pin1 Pin2 Pin3 Pin4 Pin5 Pin6 Pin7 Pin8 Pin9 Pin10 Pin11
LC-26HUXX 8.55-9.45V 0 4.75-5.5V 0 11.69-12.92V 0 4.75-5.5V 0 H
LC-32HUXX 8.55-9.45V 0 4.85-5.36V 0 11.4-12.6V 0 4.85-5.36V 0 H
Measure the pin voltage of XS16, the data is shown in table2:
Table2 voltage data of XS16
Pin1 Pin2 Pin3 Pin4 Pin5 Pin6
LC-26HUXX 0 4.75-5.5V 0 8.55-9.45V 0 30.4-33.6V
LC-32HUXX 0 4.85-5.36V 0 8.55-9.45V 0 31.36-32.64V
Measure the pin voltage of XS11, the data is shown in table3:
Table3 voltage data of XS11
Pin1 Pin2 Pin3 Pin4 Pin5
LC-26HUXX 20.25-23.63V 0
LC-32HUXX 22.8-25.2V 0
3. Alignment flow-chart
The alignment flow-chart is shown as fig-1
Check DDC, FLASH, HDCP and power control IC
Combined test for general assembly
Factory initialization setup
IF channel AFT voltage of TV and AGC voltage adjustment
White balance adjustment
3
Performance check
Preset ex-factory
Fig-1 Alignment flow-chart
4. Alignment instruction
4.1 Unit adjustments
Connect all the boards according to wiring diagram, then power on and observe the display.
Method for entering factory menu: press "INPUT", "2", "5", "8" and "0" in turn to enter factory
menu; press "CH+" and "CH-" to select adjustment items and press "VOL+" and "VOL-" to adjust
value items, press "MENU" repeatedly to exit.
Method for software upgrading: When software upgrading please enter factory menu first, select
ISP from OPTION, set ISP to 1 and you can begin to upgrade. After upgrade finished, it needs to set
ISP back to 0. If the picture can't display when upgrading, it needs to solder JB1 on main board.
Please unsolder JB1 again after upgrading.
4.2 Initialization
Enter factory menu, select "OPTION", "EEPROM" and "HOTEL OPTION" sub-menu, for adjusting
items see table 4.
Table 4 sub-menu adjustment
Items Preset Remarks
HOTEL 0 1: HOTEL OPTION of factory menu is optional
0: HOTEL OPTION of factory menu is not optional
LOGO 1 1: display LOGO in no signal or turn on
0: no LOGO display
ADC PRESCALE 046 Software will preset the data according to different status.
SIF PRESCALE 02E Software will preset the data according to different status.
BACK LIGHT FF Software will preset the data according the type of panel
ALL COLOR 1 1: white balance of each channel auto offset based on the HDMI white
balance
0: white balance of each channel adjust the offset base separately
Note: don't set ALL COLOR to 1after the offset adjustment, if you do so, the
adjusted parameter of each channel will recover to the parameter of HDMI.
EEPROM-MEMORAY > EEPROM Initialization (operate when EEPROM data chaos)
RECALL
4.3 Adjustment for AFT voltage and AGC voltage of IF channel in TV
4.3.1 IF AFC adjustment
Disconnect J1(B face), input 38.9MHz PAL signal of 80dB to the pole of J1 near L11, Adjust L5
to value 1.25V of TP2. Enter factory menu, adjust TDA4470 from BG to LL, input 33.9MHz SECAM
signal of 80dB, adjust R71 to value 1.25V of TP2 then solder J1.
4.3.2 IF AGC adjustment
Input 184.25MHz(PAL/BG) RF signal of 60dBuv to RF terminal, adjust R64 to value 4V of TP4
and there should be no obvious snowy picture. Increase the signal to 90dBuv and it should be
display normally and no obvious noise.
4
4.4 White balance adjustment
4.4.1 white balance adjustment of HDMI
a. Input VG-849 signal from HDMI: TIMING854 (800* 600/60Hz) and eighth-level gray scale
signal of PAT920. Use color analyzer CA210 to adjust white balance.
b. Enter submenu of COLOR TEMP, Select 9300k of color temperature
c. Fix value of B OFF, adjust R OFF and G OFF, let the color coordinate of the second level be
(285, 293) and the brightness be about 3nit-6nit. Fix value of B GAIN, adjust R GAIN and G GAIN,
let the color coordinate of the seventh level be (285, 293). Adjust R OFF, G OFF, R GAIN and G
GAIN repeatedly until the value of the two levels gray-scale are (285, 293).
4.4.2 VGA/YPBPR/AV white balance check and correct
a. Connect VG-848 signal of VGA to VGA terminal: TIMING854 ( 800 x 600 / 60Hz)
(PATTERN:CROSS) and auto adjust to full screen, then input PAT948 black/white signal, enter
factory menu ADC ADJ, select AUTOTUNE and wait for OK display. Input PAT920(8 gray levels),
check if the white balance is normal, if not, enter COLOR TEMP menu and set ALL COLOR to 0 and
fine adjust according to the method of 4.4.1c)
b. Connect VG-848 signal of YPBPR to YPBPR terminal and input TIMING972(1080i/60HZ)
100% color bar of PAT976(include black/white bars), Enter ADC ADJ submenu, select AUTOTUNE
and wait for OK display. Input PAT920(8 gray levels), check if the white balance is normal, if not, set
ALL COLOR to 0 and fine adjust according to the method of 4.4.1c)
c. Connect AV signal (PM5518, 8 gray levels, NTSC) to VIDEO1 terminal, check if the white
balance is normal, if not, set ALL COLOR to 0 and fine adjust according to the method of 4.4.1c)
Note: it can't set back to 1 once ALL COLOR changes to 0.
5. Performance check
5.1 TV function
Enter searching menu auto search, connect RF-TV terminal with central signal source and check
if the picture is normal, if there are channels be skipped. Check TXT and parental control.
5.2 AV, YPbPr terminals
Input AV/S, YPbPr/YCbCr HD signal, check if the picture is normal.
5.3 VGA terminal
Insert VGA terminal, input VGA format signal of 640x480@60 Hz and check if the display is normal.
5.4 Check sound channel
Check the speaker of each channel.
5.5 Other function check
Check the ON/OFF timer, sleep timer, picture/sound mode, OSD, freeze/mute, stereo, etc.
5.6 Presetting before ex-factory
Item Setting Item Setting Item Setting
PICTURE MODE STANDARD BALANCE 50 OSD LANGUAGE English
COLOR MODE NORMAL VOLUME 50 OSD HPOSITION 50
NR WEAK SLEEP TIMER OFF OSD VPOSITION 50
ZOOM FULL TTX LANGUAGE WEST OSD HALFTONE 50
SOUND MODE STANDARD BLUE SCREEN OFF OSD DURATION 15
AVC OFF WSS OFF
5
6. Software instruction
Software instruction
No. Code No. Type Function Flash written Method
before paste
NS14 5270008001 ATMEGA8L Power managementIC Yes Written with
NS3 5272540001 PM25VF040 Main CPU program Yes instrument like
NB3 5272402002 24C02N-10SI27 HDMI EDID Yes ALL11
NB7 5272402002 24C02N-10SI27 VGA EDID Yes
NS5 5272404002 24C02N-10SI27 Store some important No No written
information software
Method of software upgrading
1. The tools and software demanded
1) Please confirm that PC has the software of ISP_TOOL and install the parallel interface drive
program Port95nt.
2) ISP_TOOL icon is bellow:
3) One parallel cable (25 pins) and one VGA cable (15 pins), the parallel cable connects the PC and
the upgrade instrument, the VGA cable connects the TV and the upgrade instrument.
2. The steps for upgrading software
1) Please confirm that the connection wires and the upgrade instrument are connected well before
the software written and then power on the TV.
2) Double click the icon ISP_TOOL to open it:
6
3) Press "Connect" to connect TV, if the connection is done successfully as shown below, then
press "enter".
Note: if it appears error, check the connection wires and check if ISP item of the factory menu is set
to 1, if not, please set it to 1.
4) After connection is done, it needs to read the Binary document. Press "Read" as shown below:
5) Search the document needed to write in the "Read" check box.
7
Select
6) Select the document then the window will appear as shown below:
8
7) Press "Auto" to select the writing function.
9
Select the items shown in the picture above:
(a) Read File
(b) Program
(c) Exit ISP
(d) Erase Device
(e) File Area
8) Press "Run" to begin the writing program, wait till the blue bar is complete.
After writing, it will display OK:
If there is error appeared (shown as below), press "Run" again to rewrite the program till it is
success.
10
Note1: keep the connection well and don't cut off the power during the writing process.
Note2: the writing speed can be adjusted as shown below. Select "Config" then adjust Speed BAR,
the value is bigger the speed is faster. But it is easier to appear error when increase the speed, so it
need to select a suitable speed according the PC.
Step 1
Step 2
11
Working principle analysis of the unit
The RF signal received by antenna will be sent to tuner TUNER101, then IF signal will be
obtained through high amplifier and mixed frequency, through pre-intermediate amplified by V15,
then it will be sent to SAW filter Z17 to do IF filter and get better IF characteristics, then it will be sent
to N3 (TDA4470) to do intermediate amplification, phase-locked loop VCO and synchronous wave
detection to get video signal TV-V; after pre-intermediate amplification IF will also be sent to SAW
filter Z16 to do filter at the same time, then it will be sent to TDA4470 to do intermediate
amplification and output the second sound intermediate frequency signal (TV-SIF).
The TV-V signal output from TDA4470 together with TV-SIF will be sent to main chip
NS2(MST9E19B).
Video signals of VGA and HDMI will be sent to MST9E19B, too.
Video signal of YPbPr and Video RGB of SCART1 via video switch N5 (PI5V330) will be sent to
MST9E19B.
Video signal V (CVBS) of SCART1, YPbPr L/R and SCART1 L/R will be sent to MST9E19B.
The main chip NS2(MST9E19B) is a high performance and fully integrated IC, which can
realize HDMI processing, video demodulating, video switch selection, A/D and D/A conversion,
interlace/progressive processing, modes conversion, OSD and low-voltage differential output, etc.
And it also has functions of audio selection, processing and MCU.
The video signal via MST9E19B processing, output LVDS signal (3 pairs differential signal and
1 pair clock signal) to T-CON chip N504 (CM1671A), after transform to RSDS signal, sent for LCD
panel display. TV-V output from N3 (TDA4470 via double video amplifying, it will be sent to SCART1
for AV-OUT.
Audio signal via MST9E19B processing will be sent to sound amplifier NV1 (TDA7266SA)
amplifying to speaker. TV-SIF via MST9E19B demodulating and sound processing then output to
NV3(LM358D) amplifying, the signal will be sent to SCART1 as AV-OUT.
12
Block diagram
EDID
24C02
VGA FLASH
YPbPr HDTV SW.
EEPROM
PI5V330
SCART1-RGB
LCD TV
SCART1-V CONTROLLER
SCART1-L/R T-CON PANEL
HDMI MST9E19B
CM1671A
L/R-VGA
L/R-YPbPr
L/R
TUNER AUDIO AMP.
PRE AMP
TDA7266SA
SAW
SPEAKER
IF AMP TV-SIF
TDA4470 TV-V
SCART1-V OUT 2*AMP
TV-L/R PRE AMP SCART1-L/R OUT
LM358D
13
IC block diagram
1. MST9E19A
The MST9E19A is a high performance and fully integrated IC for multi-function LDC monitor/TV with
resolutions up to SXGA (1280X1024)/WXGA+(1440X900). It is configured with an integrated
triple-ADC/PLL, an integrated DVI/HDCP/HDMI receiver, a multi-standard TV video and audio
decoder, a video de-interlacer, a scaling engine, the MStarACE-3 color engine, an on-screen
display controller, an 8-bit MCU, and a built-in output panel interface. To further reduce system costs,
the MST9E19A also integrates intelligent power management control capability for green-mode
requirements and spread-spectrum support for EMI management.
14
2. TDA7266SA
The TDA7266SA is a dual bridge amplifier.
15
3. TDA4470
The TDA4470 is an integrated bipolar circuit for multi-standard video/sound IF(VIF/SIF) signal
processing in TV/VCR and multimedia applications. The circuit processed all TV video IF signals
with negative modulation (e.g., B/G standard), positive modulation (e.g., L standard) and the AM,
FM/NICAM sound IF signals.
16
17
Trouble shooting
1. Fault clearance
Before servicing please check to find the possible causes of the troubles according to the table
below.
1.1 Antenna (signal):
Picture is out of focus or jumping Bad status in signal receiving
Poor signal
Check if there are failures with the electrical connector or
the antenna.
Check if the antenna is properly connected.
Fringe in picture Check if the antenna is correctly oriented.
Maybe there is electric wave reflected from hilltop or
building.
Picture is interfered by stripe shaped Possibly due to interference from automobile, train, high
bright spots 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.
Maybe the shielded-layer of signal wire is not connected
properly to the connector.
There appear streaks or light color Check if interfered by other equipment and if interfered
on the screen possibly by the equipment like transmitting antenna,
non-professional radio station and cellular phone.
1.2 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
19
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 Check if the setting for the brightness is too high
darkest area of the picture Possibly the brightness grade of DVD player (broadcaster)
is set too high.
No picture or signal produced from Check if the cable is disconnected.
the displayer if "XXX in search" Check if it's connected to the proper terminal or if the input
appears. mode is correct.
There appears an indication - Check if the TV set can receive input signal. The signal is
"outside the receivable scope) not correctly identified and VGA format is beyond the
specified scope.
Remote control cannot work Check if the batteries are installed in the reverse order.
properly 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 Check if the antenna cable is correctly connected, or if it
hash. has received the video signal correctly.
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 When being played or in pause VHS picture search tape
tape, there are lines at the top or sometimes can't provide stable picture, which may lead to
bottom of the picture. incorrect display of the liquid crystal TV, In 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
20
2. Troubleshooting guide
2.1. No raster
Turn-on power supply, check yes
if the red indicator is light in
the STANDBY?
no
Check if PIN9(5V) of X403 Press POWER button on the red
on main board is normal? unit or remote control and
check the indicator.
blue
no
Check if the PIN2,3 of X401
Check STANDBY circuit of
on main board is high-level?
power supply board
yes
Check back light board
no
no
Check NS2 and its Check if the PIN11 of X403 on
peripheral circuit main board is low-level?
yes
Check NS14 and its Check power
peripheral circuit supply board
21
2.2. Raster appears, but no picture
Check if the OSD menu
Check if the unit button can be displayed yes
yes
and remote control are normally after pressing
active? MENU.
no
no Check if all channels
yes
have no signal?
no
VGA/SCART(CVBS)/HDMI
Enter factory-menu, Which channel has
initialize EEPROM, no signal ?
no
Replace then turn off the TV,
Replace
main board turn on again, check if
TV main board
picture appears?
YPBPR/SCART(RGB)
yes
Adjust main board
again Check if N5
Check if TP1 on the output signal?
yes TV board has 1VPP
no
signal or noise? yes
Replace
N5
no
Replace
Check if output main board
Check TUNER101 no IF signal of
and its periphery TUNER101 (pin
11) is normal?
yes
Check N3 and its
periphery
22
2.3. No sound (Use TV input as an example)
Check if PIN 3, 13 Check the waveform
yes yes
voltage of NV1 is of PIN 4, 12 of Check NV1
normal? NV1 and its periphery
no
no
Check power supply
Check N3 PIN 24 yes
Check NS2 and its
waveform.
periphery
no
Check TUNER101 yes Check N3 and its
PIN 11 waveform. periphery
no
Check TUNER101 and
its periphery
23
5
2
6
3
7 4
8 5
9 6
IR
30 7
Key
8
31
Back Light
9
32
Back light
33 0
Appendix-A: Board List (9232HU2628)
Board Name No. Main components & its No.
Main board 6HU0860110 N3 TDA4470MFL (5274470001)
NV1 TDA7266SA