Xoceco LC20H3D Schematic

COLOR TELEVISION

LC20H3D

CONTENT

Safety instructions………………………………………………………………………..… Instructions on adjusting and testing…………………………….…….………………… Trouble shooting……………………………………………………….…………………… Method of software upgrading………………………………………….………………… Brief introduction and working principle of L20H3………………………………..………….

Wiring diagram……………………………………………………………..……………....

Serial NO. of parts……………………………………………………………………….… Identification criteria for the bright spot and dark spot of the LCD screen………..…. Troubleshooting guide………………………………………………………………..……

Exploded view…………………………………………………………………….…..........

Part list................................................................................................................. 25

1 2 6 8 9 19 20 20 21 23

Schematic diagram...............................................................................................43

ttention: This service manual is only for service personnel to take reference with. Before servicing

please read the following points carefully.

Safety instructions

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 to be taken (throughout the entire production 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 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 swit ched 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 subst ance suc h as water, liquid, met al slice s or other mat ters happ ens to fal l 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, abnor mal s mell or sou nd fro m the modu le, pleas e shut t he power of f 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 befor e t he pulling out or plugging in the connection wire.

2.8. When operating or ins tall ing LCD p lease don’t subject the LCD c omponen ts to bending, tw isting or extrusion, collision lest mishap should result.

2.9 As most of the c ircuitry in LC D TV set is compose d of CMOS int egrated c ircuit s, it’ s nece ssary 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 ta ke care not t o t ouch 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 t aken in tr ansport ing or hand lin g it. Exquis it e shock v ibration 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-m oisture bag and put them altogether in one place. The ambient conditions are tabulated as follows:

Temperature Scope for operation 0----+50 C Scope for storage -20----+60 C 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 commmonly called “ghost shadow”. The extent of the residual pictu re 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 min u t es).But when operating it please avoid displaying still picture in high brightness for a long time.

3.Points for att e nt i on dur ing installati on

3.1. The front pa nel of L CD screen is of gla ss. Wheng inst alling it plea se make sure t o put it in plac e.

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 f oreign substance that happens to fall down between the screen and the glass will affect the r eceiving and viewing effect

3.4. When dismantling or m ounting 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 t r ouble.

3.5. Be sure to protect the cabinet from damage or scratch during service, dismantling or mounting.

Instructions on adjusting and testing

1.Adjusting and calibrating equipment

Digital multi-meter (or oscilloscope) 5515 signal generator 5518 signal generator PC set(FLASH writing programs have to be inst alled first. ) K7253(VGA, YprPb signal generator) CA210 (LCD white balancer) DVD broadcaster

2.Flow chart for the adjustment and calibrationSee 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 satellite signal, check if v ar ious TV

functions (station skipping, modulate quantity control etc), check if the

output of earphone and speaker are normal

Input AV/S terminal signal, check

different functions of AV/S terminals

Input VGA signal and check if display is normal in

the state of PC and various functions (analog

quantity control, line/field center etc.)

Input YprPb signal, check if the display is normal unde 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.Flash writing programs

Flash write memory N4, N20, N303, N302

4.Adjustment and calibration for the main board

a)Connect the main board X501 to infrared receiving board (as per wiring diagram 203-L15H30-01JL) and insert the plug of power supply adapter (FSP048-1AD101C for15”, FSP060-1AD103 for 17”, 20”) into X1. Now the indication lamp of the infrared receiving board is red.

b)Connect PC, upgrade the program of FLASH N20, push the POWER key on the remote control set. Now the indication lamp of the infrared receiving board is out.

c) About 4 minutes later the indication lamp of the infrared receiving board turns blue or yellow. Measure L102 PIN2 to be5.0 V, measure L107 PIN2 to be 3. 3 V.

d) Flash write DDC program.

5. Adjustment for the TV board

Connect the main board and in frared receiving bo ard (as per w iring diagram 203-L1 5H30-01JL) and press the POWER key on the remote contro l set . No w the indic at ion la mp of th e infrared rec eiv in g boar d is blue or yellow. Measure N301 PIN2 of TV board to be 3.3 V, one terminal of inductor L630 to be 5 V and one terminal of inductor L632 to be 12 V

6.Adjustment of white balance (using the white bala ncer C A210 and K7253 signal generator specialized for LCD)

a).Install the whole TV set

b).Enter the factory menu and perform”PW1306 reset”

c).Exit from the factory menu. Press “signal source” key and enter YPbPr .

d).Input YpbPr signal: 640x480p 60Hz (K7253).

e).Enter the user menu. Set the brightness to 50 and cont rast to 50. Press “fa ctory” key to enter the factory menu, perform “ADC calibration”, input signals of “black field”(EMPT),”white field”(White-(100%))”fully red”(Full_Magenta)respectively and then calibrate three times.

f).Input signal of “eight grade gray”(Gray(H)-8 ). Use CA-210 to measure the sixth grade and adjust the brightness and contrast so that Y is around 180. Enter factory menu and adjust the green color temperature and blue color temperature so that x=270,y=283(red color temperature is constant as128).

g).Exit from the factory menu and enter route RGB. Input 60Hz “pane signal ” (C_Hat_16x12(W)) through port VGA. Enter the user menu and adjust the brightness to 50 and contrast to 50. Adjust the line center and the field center so that the picture is correctly positioned.

h).Input signal of “16 gray grades” (Gray(H)-16). Enter the factory menu and perform “calibration of ADC”.

i).Exit from the factory menu, input the signal of “eight grade gray” (Gray(H)-8 )and enter the user menu. Adjust the brightness and contrast. Use CA-210 to measure the sixth grade so that Y is around

180. Enter the factory menu and adjust the green color temperature and blue color temperature so that x=284,y=299(red color temperature is constant as128).

j).Enter the factory menu and a djust the green color t emperat ure and blue color temperature so that 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”

17”

20”

7.Performance check a).TV Interfaces Connect RF port to central signal source. Enter station search menu - auto station search. After system adjustment is over, check if there is any station missin g and then ch eck se mi-auto stat ion search .

AU Sanyo CPT Samsung AU AU 800x600 Chimei LG

1024x768

1280x1024

640x480

Check if fine tuning is normal.

Check if the output of earphone or loudspeaker is normal and if the picture is normal. b).Interface of AV/S Terminals

Connect to access the signal of AV/S terminals separately and check if the picture or sound is normal. c).A V OUT Termianl

Input the signals separately in the status of TV/AV/S terminal. Connect AV OUT terminal to monitor and check if the output picture and sound from AV OUT is normal. (Note: In the status of S terminal, the output picture from AV OUT is colorless.) d).VGA Interface

Input VGA signal(K7253 signal generator). Separately input the four types of VGA format signals as listed in Table 1. Wait till auto calibration is over. Then check if the picture and sound is normal. If there has been interference to the picture then press the auto set key on the remote control once again and check if the display is normal.

Table 2.VGA format signal

screen size resolution Image clock(MHz) H-SYNC(kHz) V-SYNC(Hz) remark

640x480 @ 60 25.175 31.469 59.900 720x400 @ 70 28.322 31.469 70.086 800x600 @ 60 40.000 37.879 60.317

15”

17”

20”

e). YprPb Interface

Connect to access YprPb signal(K7253 signal generator). Separately input the five types of YprPb format signals -- 480P/50 Hz,480P/60 Hz,720P/60 Hz,1080I/50 Hz,1080I/60 Hz and check if the pi cture and sound is normal after auto calibration is over.

Connect to access YprPb signal(DVD signal generator). Input the signals -- 480I/50Hz,480I/60 Hz

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 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

CMOscreen nonsupport CMOscreen nonsupport

separately and check if the picture and sound is normal.

8.Preset ex-works

In the status of TV enter the factory menu by pushing the factory key and then perform presetting.

9.Ex-works packing

Check accessories and then pack them in box.

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 w a ve reflected from hilltop or building. Picture is interfered by stripe shaped bright spots

There appear streaks or light color on the screen

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.

Check if interfered by other equipment and if interfered possibly

by the equipment like tran smitt ing anten na, non prof essiona l radio

station and cellular phone.

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 c onnect ed to the w rong ter minal or if the input mod e

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 tone Screen position or size is not proper Picture is twisted and deformed Check to see if the picture-frame ratio is properly set up.

Check if all the picture setups have been corrected.

Check is the screen position and size is correctly 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 distortion in the brightest area

Picture is whitish or too bright in the darkest area of the picture

No picture or signal pro du ced fro m the displayer if “XXX in search”appears. There appears an indication “outside the receivable scope)

Remote control cannot work properly

No picture and sound, but only hash.

Check if the contrast setting is too high.

Possibly the output quality of DVD broadcaster is set t oo high.

It maybe also due to improper terminal connection of the video

frequency signal in a certain position of the system.

Check if the setting for the brightness is too high

Possibly the brightness grade of DVD player(broadcaster)is set

too high.

Check if the cable is disconnected.

Check if it’s connected to the proper terminal or if the input

mode is correct.

Check if the TV set can receive input signal. The signal is not

correctly identified and VGA format is beyond the specified

scope.

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 wind ow is exposed

to strong fluorescence.

Check if the antenna cable is correctly connected, or if it 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 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 liq uid cryst al TVIn this c ase ple ase 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

Steps of soft w are upgrading are as follow s:

1.Select a serial connection wire and a VGA connection wire and then connect them by means of a patch panel;

2.Use a serial wire to connect the PC to the patch panel and set TV set to off state;

3.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 pr ogr am:

Based on the computer features, set u p the serial port(CO M Port ). Se lect c orrespondi ng seri al 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 w r ite 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.

Brief introduction and working principle of L20H3

LC20H3 multi-media liquid crystal TV broadcast and receiving set adopts liquid crystal display screen of LG 20.1, which is provided with NTSC color system receiving function in addition to AV input,S-VHS input,high de finit ion sig nal port for component Y PrPb/YcbCr,PC VGA port, earphone out put and other signal ports. For power supply an externally connect ed power adaptor is provided.

The circuitry of LC20H3 is composed of RF module board, video signal board, digital signal picture processor and AC-DC tr ansformer, and DC-DC circuit board.

The working process is as follows. The radio frequency signal undergoes an integrated tuner TUNER1 before a color full video signal is generated. This video signal then enters analog board decoder IC N303 VCT383 3 Pin1 9 where it is proc es sed and it’s output as analog signals R, G, B through Pin42, PIN43, PIN44. Audio frequency signal is processed with sound in IC N401 MSP3420G and then output through MSP3420G Pin28 , Pin27 to SRS for surround sound processing in IC N403 M62494E. Finally it is subject to power amplification in IC N404 TDA1517 before it is output to speaker.

VGA signal/high definition signal is input to personal com puter through the main board. The signal selected by Y/Pb/Pr through 5 way 1/2 switches IC(N1 BA7657F)is subject to reselection together with signal TVRAIN, TVGAIN, TVBAIN through 5 way 1/2 switches IC(N5 BA7657F). Finally signals R, G, B are selected and sent to the main processing chip IC N19 PW1306.

IC N19 PW1306 is a built-in X86 CPU of the main processing IC,externally connected by 8M Flash(N20) memory to control the whole system. The input signal of V-port and G-port is subject to internal arithmetic processing and then output as R, G, B signals with electric level of 24 bit TTL to sockets JP3 and JP4, where through conn ection wires the signa ls are sent to the port of LG liqu id cryst al screen and for the realization of picture reproduction.

BLOCK DIAGRAM

IC BLOCK

DET

Logic

Syncsepa

Ground

CTL (H: IN1, L: IN2)

Red 1 input

Green 1 input

Blue 1 input

Red 2 input

Green 2 input

Blue 2 input

VD 1 input VD 2 input

VD output

Blue output

Composite sync output

Composite video input (Sync on Green)

Green output

Red output

HD output

HD 2 input

HD 1 input

HD Sync signal detector

BA7657F / BA7657S

PW130

DRGB (23:0)

DGRGB(23:0)

DVS, DHS,

DEN, DCLK

RxDTxD

NMI

(1:0)

(15:0)

(19:1)

JTAG Debugger

UART

Interrupt

Controller

Time rs

Watchdog and

RAM Interface

Processor ROM/

16-Bi t

Micro processor

Seri al

2-Wire

Microprocessor Bu s

OSD

Memory Out Bus

Color

Space

Expander

Color

Ta b le s

Lookup

and

OSD

Gain

Color

Matrix

Ti mi n g

Displa y

Generator

Internal Block Diagram

PW130 ImageProce ssor

PLL and

MCL K DCLK UCLK

XI XO

Oscillator

Scaler

Decoder

Reset

Memory

Interface

Processor

PortA(7:0)

GPIO PWM

Buffer

Memory

Auto Image

Memory In Bus

Opti miza ti on

Reset

PowerOn

RESET

Figure 1-1 ImageProcessor Block Diagram

Data

MUX

PORTD (7:0)

HSHSYNC,

CLK

ADC

VIDEO

CLK

RGB

HS,VS

Color

Space

Converter

VPEN

VCL K

VYU V(7:0)

Sync

Pro cessing

SOG

Stripper

FILT PLL

SOGIN

VSYN C

A/ DClamp

AIN

A/ DClamp

A/ D

Clamp

AIN

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