Xoceco LC27K6 Schematic

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 glov es.

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 ident ical with the TV set. Otherwise it will cause fire or damage to

the set.

2.4 Never operate the set or do any inst allat ion wor k in bad env iron ment such as w et bathroo m, la undry , kitchen,or nearby fire source, heati ng equ ipme nt an d device s or ex posur e to s unlight et c. Ot herwi se bad effect will result.

2.5 If any foreign substance such as water, liquid, metal slices or other matt ers 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, abnorma l smell or sound fro m the module, pleas e shut t he 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 befor e t he pulling out or plugging in t he 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 T V set is comp osed of CMOS i ntegrate d circuits, it’s neces sary 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 ne cessary to hou se it in a n ant i-moist ure bag an d put them altogether in one place. The ambient conditions are tabulated as follows:

Temperature Scope for operation Scope for storage humidity Scope for operation Scope for storage

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.

0—+50 C

-20—+60 C 20%—85% 10%—90%

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 v iew ing 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

PM5518(Video signal generator),K-7253(VGA signal generator),CA210(White balancer

2.1. Adjustment and calibration flow process For adjustment and calibration flow process diagram, see figure 1

Combined test for general assembly

Connect to central sign al source, check i f various TV functions (station skipping, modulate quantity control etc), check if the output of earphone and speaker are normal

Input AV/S, HDTV signal and check various functions under terminals

Input VGA signal (one format) and check if display is normal in the state of PC and various functions (analo quantity control, line/field center etc.)

Figure 1 Flow process of Adjustment and calibration

Check accessories and then packing

2.2 Adjustment and calibration of complete set

Connect different CP U board and an alog board acc ording to conne ction dia gram 2 03-L27K60-0 1JL. Put power supply on, see if the display is normal. Method to enter factory menu: Continuously push “VOL+” “Mute” and “Video” keys to enter the factory menu; select different items of adjustment and calibration, when the first line of each adjustment item is in high brightness; push the “ENTER” key to select different adjustment item; push “ENTER” key after the mode is selected with VGA input and select three color temperatures 6500K,9300K,12000K; push “MENU” to quit the factory menu.

Figure 1

Check CPU and analog b oard

Preset before outgoing from factory

Note: The white balance adjustment should be made in the mode of “Nature” picture.

2.2.1 EPROM Initialization Enter the first page of factory menu, push “ENTER” key after the selecting Clear EEPROM, shut off the pow er supply after the appearance of “OK”.

2.2.2 VGA and DV1 channels adjustment

2.2.2.1 VGA channel mode preset

Input VGA signal of K-7253(PATTERN 5:Final Test),select TIME301 (640*350/70Hz), push ”AUTO” key to automatically adjust to make the picture full of the screen, same, to automatically adjust respectively TIME302 (720*400/70Hz) ,TIME303 (640*480/60Hz), TIME311 (800*600/60Hz), TIME313 (1024*768/60Hz), TIME315 (640*480/75Hz), TIME316 (800*600/75Hz), TIME317 (1024*768/75Hz), TIME319 (1280*1024/75Hz), and TIME339 (1280*1024/ 60Hz).

2.2.2.2 ADC adjustment of VGA channel

Input the signal of 64 grades of grey density to K-7253 TIME311, PATTERN474, set the adc-gain to max.(Not exceeding 18) so that the brightest two grades are distinguishable.

2.2.2.3. White balance adjustment of VGA and DV1 channels

Input the signal of 8 grades of grey densit y to K-7253 TIME311,PATTERN471, enter the adjustment menu of white balance. Use the white balance to adjust second and seventh grades.

Select mode to be 6500K,adjust offset_R, offset_G, offset_B, to adjust the second grade color coordinate to be 313,329 and the brightness to be about 3.5 nit. Adjust gain_R, gain_G, gain_B so that seventh grade color coordinates are 313,329. Adjust offset_R, offset_G, offset_B and gain_R, gain_G, gain_B,again and again until two grads of grey density are all set t o 313,329.

Select mode to be 9300K,adjust offset_R, offset_G, offset_B,so that the second grade color coordinates are 285,293 a nd the br ightn ess a bout 3. 5 nit .Ad just gain_ R, ga in_G , gain_ B s o that sev ent h grade color coordinates are 285, 293. Adjust offset_R, offset_G, offset_B and gain_R, gain_G, gain_B, again and again until two grads grey density are all set t o 285, 293.

Select mode to be 12000K.Adjust offset_R, offset_G, offset_B,so that the second grade color coordinates are 270,283 and the brightness about 3.5 nit. Adjust gain_R, gain_G, gain_B, so that the seventh grade color coordinates are 270, 283. Adjust offset_R, offset_G, offset_B and gain_R, gain_G, gain_B, again and again until two grads grey density are all set t o 270, 283.

Notice: The value of gain_R, gain_G, gain_B should not exceed 128, and at least one of the values should be guaranteed to be 128

2.2.3 TV channel adjustment

2.2.3.1 Adjustment of VCO, OPTION, sub-brightness and sub-contrast

Input the AV color bar signal(PM5518 COLOUR BAR 100%)to VIDEO 1 terminal, enter the first page of factory menu. Select auto color, push key “ENTER”. About two seconds later, OK is displayed, showing the adjustment is over. Adjust the value of Option to be 11,S-bright to be 124,S-contrast to be 140, and Max Volume to be 30.

2.2.3.2 White balance adjustment of TV channel

Input AV signal (PM5518,NTSC system, eight grades of grey density signal), enter the adjustment menu of white balance. Use t he white balanc er to adjust the second and sev enth grad es. Adjust of fset_R, offset_G, offset_B,so that the second grade color coordinates are 255,240 and the brightness about 3.5 nit. Fix gain_B to be 128, adjust gain_R, gain_G, so that the seventh grade color coordinates are 290,

285. Adjust offset_R, offset_G, offset_B and gain_R, gain_G again and again until two grads of grey

density are all set to regulated value.

2.2.4 White balance adjustment of Yp rPb channel

Input YPbPr signal of K-7253 to D4-1 terminal,input eight grades of grey density signal of TIME380(480i)PATTERN471, adjust S-bright to be 120,S-contrast to be 140. Enter the adjustment menu of white balance,adjust second grade with balancer. Adjust offset_R, offset_G, offset_B sot that the second grade color coordinates are 255,240 and the brightness about 3.5 nit.

Separately input eight grades of grey density signal of mode TIME392(480p),TIME394(720p)and TIME396(1080i). Repeat the above operation, so that the second grade color coordinates are 255,240 and the brightness about 3.5 nit.

3. Function inspection

3.1 TV function

Enter the search menu → auto search, connect RF- TV terminal to t he central signal so urce, check if there is station skipping.

3.2 AV/S, HDTV terminal

Connect AV/S and HDTV signal, check if they are normal.

3.3 VGA connector

Insert VGA signal connector, input format signal 640 x 480@60 Hz VGA, check if the display is normal. If there is interfere in picture, push the adjustment key on the remote control set one more time, check if the display is normal.

3.4 Sound channel inspection

Check if the output of each speaker and earphone channel is normal.

3.5 For factory preset, see table. 1

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 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 transmitting antenna, non professional 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 connected to the wrong terminal or if the input mode is

correct.

 Check if th e sig nal cable connection between video frequenc y source

and the liquid crystal TV set is correct. Deterioration of color phase or color 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

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 produced from the

displayer if “XXX in search”appears.

There appears an indication - “outside the receivable scope)

 Check if all the picture setups have been corrected.

and make proper adjustment according to the signal types.

 Check if the contrast setting is too high.  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.

 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. 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 correct ly conn ect ed, or if it ha s receiv ed

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.

 W hen being played or in pause VHS picture search tape sometimes

can’t provide stable pi cture, wh ich may lead to i ncorrect displ a y 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

Principle analysis of LC-27K6

For the working principle of LC-27K6 please refer to LC-27K6 bloc k diagra m of the complete TV set.

Following is a short description of the signal flow:

RF signal through an integral tuner TUNER201 produces complete color TV signal which is input, together with AV1/SVHS(SVHS in priority ) and AV2 video signals, into U 29 VPC3230D for conversion selection and decod in g. Except for being decoded the selected video s ign al is divided in two routes: one is fed to AV output terminal and another route of signal to special 21 line decoder U32 Z86229 of CCD/V-CHIP for decoding. After decoding by U32, the signal is sent b ack to U 29 wi th R,G,B,FB f ormat and superimposed to the original picture decoded, then sent to U13 FLI2310 in ITU-R656 of 8B1T format for progressive line processing.

YPbPr signal, after analog to digit al conv ersion by U30 MST9883 into YUV with 24BIT is al so sent to FLI2310.

Above two routes of signal are processed by FLI2310 for matrix, color density and tint and then output as RGB with 24 BIT into the main processor chip U12 JAG-ASM. There are other two routes of signals: one route is RGB signal o f VGA for computer, another rout e is DV1 int o RGB s ignal w ith 24 bit t o U12 through interface of U15 TFP403/501. Three routes of signal are processed in U12 for picture format. Among them, one route of VGA after A/D conversion for RGB is subject to selection for conversion, together with other two routes, and then processed for digital display including OSD AND GAMMA correction, and brightness and contrast processing and changed into 1024*768 format. The RGB signal with 24BIT is output to the LVDS converter, U31 DS90C383A, for conversion into the signal format which the screen can accept, that is, three pairs of low voltage differential signal and one pair of time signal. And they are further sent to LCD screen for picture display. The PWM of U12 is also used to control the brightness of the background light. The second sound IF signal SIF output from tuner is sent to sound frequency processor N201 MSP3420; the sound frequency signal of YPRPB,and DVI is also sent to N201 after switching over and selection by switch U34 HEF4052. The AV1/SVHS,AV2 and VGA audio signal are also sent to N201 respectively, where the second sound IF SIF is f irst de modulat ed to the aud io signal w h ich, toget her w ith four way audio signal, is selected for conversion, and then further sound magnitude controlled and sound effect treated. The out put of le ft and right signal R/L is divide d into two routes: one is sent to SRS sound field processor N203 M62494 for SRS surrounding sound processing, and further used to drive the speaker after the D-type sound power amplification N207 LX1722 and amplification of N205,N206,N208,N210 SI4532DY; the other route is used to drive earphone after power amplification N212 TLE2142. Power is supplied from power adapter and then converted into the power required by various channels and circuits.

LC27K6 BLOCK DIAGRAM

VGA

DVI

AV1-V/S-Y

SVHS-C

AV2-V

AV-V OUT

PI5V330

U15 DVI receiver

TFP403

TUNER201

VIDEO DECODER

VPC3230

U29

FBV

RGB

U32

CCD V-CHIP Z86229

U30

ADC

MST9883

RGB

SIF

ITU-R656

8bit

24bit YUV

RGB 24bit

U13

DEINTER

LACER

FLI2310

U14

SDRAM

I C BUS

EEPROM

RGB 24bit

U12

SCALER

RGB 24bit

JAG-ASM

U19

SDRAM

U20

SDRAM

MICRO-CONTRLER

TSC80251G2D

U31

LVDS

DRIVER

DS90C383A

FLASHMEMORY

IR/KEYBOARD

PANEL

YPrPb2

YPrPb1

SIF AV1/SVHS-R/L AV2-R/L VGA-R/L

YPrPb1-R/L YPrPb2-R/L DVI-R/L

AV-R/L OUT

N201

HEF4052

U34

AUDIO

PROCESSOR

R/L

MSP3420

N203

SRS 3D STEREO

CONTROLLER

M62494

R/L

N212

TLE2142

R/L

HEADPHONE

N213 N214

AUDIO

AMPLIFIER

MP7720

R/L

SPEAKER

IC BLOCK DIAGRAM

1.MSP3420

Pins description:

2,3 PIN:SCL,SDA applied for control the operation of IC . 27,28 PIN:output left and right sound channel R/L to speaker processor. 36,37 PIN:AV OUT of sound R/L. 47,48 PIN: 50,51 PIN:Input of VGA. R/L 53,54 PIN:Input of AV2 R/L. 56,57 PIN:Input R/L of 67 PIN:Input TV SIF.

DVI/YPbPr1/YPbPr2 selected input R/L.

AV1/SVHS

2.VPC3230

Pins description:

31-34, 37-40 PIN:output format signal of.ITU-R656 70 PIN:Video of AV OUT 71 PIN:Input C of SVHS. 72 PIN:input Video (SVHS in priority) of Y or AV1 of SVHS. 74 PIN:input Video of AV2. 75 PIN:input Video of TV.

3.JAG-ASM

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