Xoceco LC-26FB32, 32FB32 Schematic

LCD TELEVISION

LC-26/32FB32

CONTENTS

Safety precautions………………………………………………………………………..…

Alignment instructions …………………………….…….…………………………………

Method of software upgrading……………….…….……………………………………….…….

Working principle analysis of the unit……………………………….………….………….

Block diagram…………………………………..………………………………….…………

IC block diagram………………………………………………………………………..……

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

Identification criteria for the bright spot and dark spot of the LCD screen…………..

Troubleshooting guide ………………………………………………………………..……

Schematic diagram…………………………………………………………………………

APPENDIX: Exploded View

25 26 27 36

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 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 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. If the connection wires, connectors 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 dagame.

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.

Alignment instructions

1. Test equipment

PM5515 (video signal generator) VG-849 (YUV, VGA, HDMI signal generator)

CA210 (white balancer)

2. The alignment flow chart (see below figure)

Connect with central signal source, then check each function of TV such as

station missing, analog control etc., check the output of headphone and speaker

Input AV/SVIDEO signal, then check each function of all the terminals

Input HD signal (format), then check each function of the terminal

Input VGA, HDMI signal, check if the display is normal, check each

function such as analog control etc., check horizontal /vertical center etc.

3. Description of adjustment

3.1 Unit adjustment

To produce digital board and analog board

Check the accessories and pack them in box

Check DDC and FLASH

All testing

Adjust white balance

Preset ex-factory

Fig-1 adjustment flow-chart

Connect the digital board, analog board, video processing board, button board and remote control receiver board according to the wiring diagram 203-L27FB18-01JL or 203-L32FB18-01JL. Connect with power and observe the display.

Method for using factory menu: press ”VOL” button to decrease the volume to 0, then press”9876” to enter level one factory menu. Press ”CH+” and “CH-“ to select adjustment page, then press “OK”

to access. Press “CH+” and “CH-“ to move cursor up and down, when the cursor stays on a certain adjustment item, press “VOL-“ and “VOL+” to adjust. Press “MENU” exit to the level one factory menu; press “EXIT” to exit from the factory menu at any situation.

Note: channel switch isn’t available at adjustment menu, only after return to level one factory menu, you can switch channel.

3.2 adjustment of white balance

3.2.1 input 16 level gray-scale signal from VG849 to HDMI channel (TMIING: select a support format of HDMI), enter white balance adjustment page of factory menu, select cool color temperature of item, fixed WBGG_HDMI to 50H, adjust WBRG_HDMI, WBBG_HDMI, let the color coordinate of third level on the right be (270,283) at 400nits; fixed WBBO_HDMI to 50H, adjust WBRO_HDMI, WBGO_HDMI, let the color coordinate of third level on the left be (270,283) at 5nits. The brightness of 400nits and 5nits may obtain by adjusting the contrast and brightness of menu.

3.2.2 input 16 level gray-scale signal from VG849 to AV channel (TMIING:968), enter white balance adjustment page of factory menu, select cool color temperature of item, fixed WBGG_NTSC to 50H, adjust WBRG_NTSC, WBBG_ NTSC, let the color coordinate of third level on the right be (270,283) at 400nits; fixed WBBO_ NTSC to 50H, adjust WBRO_ NTSC, WBGO_ NTSC, let the color coordinate of third level on the left be (270,283) at 5nits. The brightness of 400nits and 5nits may obtain by adjusting the contrast and brightness of menu.

3.2.3 input 16 level gray-scale signal from VG849 to VGA channel (TMIING: select a support format of VGA), enter white balance adjustment page of factory menu, select cool color temperature of item, fixed WBGG_VGA to 128, adjust WBRG_ VGA, WBBG_VGA, let the color coordinate of third level on the right be (270,283) at 400nits; fixed WBGO_VGA to 128, adjust WBRO_VGA, WBBO_VGA, let the color coordinate of third level on the left be (270,283) at 5nits. The brightness of 400nits and 5nits may obtain by adjusting the contrast and brightness of menu.

3.2.4 input 16 level gray-scale signal of 480I from VG849 to YPbPr channel, enter white balance adjustment page of factory menu, select cool color temperature of item, fixed WBRG_YPbPr480I, WBGG_YPbPr480I, WBBG_YPbPr480I to 128, and WBRO_YPbPr480I to 128, adjust WBRO_YPbPr480I, WBBO_YPbPr480I, let the color coordinate of third level on the left be (270,283) at 5nits. The brightness of 5nits may obtain by adjusting the contrast and brightness of menu.

Input format signals separately list on table 1, repeat the operation above until the white balance pass muster.

Note: the white balance adjustment of VGA and YPBPR must be done at the situation that the white balance adjustment of HDMI is accurate.

4 Performance check

4.1 TV function

Connect RF-TV terminal to the central signal source, enter the setup menu→ auto search, check if there is station skipping, the output of earphone and speaker, the picture are normal.

4.2 AV/S-VIDEO terminal

Input AV/S signal, check if the picture and sound are normal.

4.3 YPbPr/YCbCr terminal

Input YUV signal (VG-849 signal generator), separate input YUV format signal of table 1 and check if the picture and sound are normal.

Table 1 YUV signal format

No H-frequency (KHz) V-frequency (KHz) Signal

1 15.734 59.94 SDTV 480i

2 31.469 59.94 HDTV 480p

3 44.955 59.94 HDTV 720p

4 33.716 59.94 HDTV 1080i

4.4 VGA terminal

Input VGA signal (VG-849 signal generator), separate input VGA format signal of table 2 and check if the picture and sound are normal. If the image is deflection of the H-field, select manual correction of Advanced Video Menu.

4.5 HDMI terminal

HDMI signal format receives the three high-definition signals: 480I, 480P, 720P/60Hz, 1080I/60Hz, except for the table 2 signal. Check if the image (contain HDCP ON and OFF) and sound are normal.

Table 2 VGA signal format

No Resolution H-frequency(kHz) V-frenquency(Hz)

1 720 X 400 31.469 70.086 28.322 IBM

2 640 X 480 31.469 59.94 25.175 IBM

3 640 X 480 37.861 72.809 31.5 VESA

4 640 X 480 37.5 75 31.5 VESA

5 640 X 480 43.269 85.008 36 VESA

6 800 X 600 35.156 56.25 36 VESA

7 800 X 600 37.879 60.317 40 VESA

8 800 X 600 48.077 72.188 50 VESA

9 800 X 600 46.875 75 49.5 VESA

10 800 X 600 53.674 85.061 56.25 VESA

11 1024 X 768 48.363 60.004 65 VESA

12 1024 X 768 56.476 70.069 75 VESA

13 1024 X 768 60.023 75.029 78.75 VESA

Point clock pulse

frenquency(MHz)

Remark

5 Ex-factory setting of user menu

1) Select TV channel, volume: 25

2) Video menu, Picture Mode: Nature, Aspect Ratio: Wide

3) Video menu, Advanced Video Menu: Noise Reduction——Spatial: On Noise Reduction——Speckle: Off Noise Reduction——Temporal: On Sharpness: 0

Tine: 50 Color Temperature: Cool Skin Tome: White Auto Contrast Enhancement: Off Black Bar Detection: Off 3D Y/C: On

4) Audio menu, Sound Mode: News, Balance: 31, Earphone Vo1:31

Digital Audio Output: AC-3, MTS: Mono

5) Setup menu, Tuning Band: Air

6) Feature menu, Sleep Timer: Off, Menu Language: English Note: Except for Color Temperature of Cool, the Advanced Video Menu of YPBPR/YCBCR and VGA channels sets according to the adjustment of factory.

Trouble shooting

Before servicing please check to find the possible causes of the troubles according to the table below.

1.Antenna(signal):

Picture is out of focus or jumping z Bad status in signal receiving

z Poor signal z Check if there are failures with the electrical connector or

the antenna.

z Check if the antenna is properly connected.

Fringe in picture z Check if the antenna is correctly oriented.

z 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

2.TV set:

Symptoms Possible cause

Unable to switch the power on z Check to see if the power plug has been inserted

No picture and sound z Check to see if the power supply of liquid crystal TV has

Deterioration of color phase or color tone

z Possibly due to interference from automobile, train, high

voltage transmission line, neon lamp etc.

z Maybe there is interference between antenna and power

supply line. Please try to separate them in a longer distance.

z Maybe the shielded-layer of signal wire is not connected

properly to the connector.

z Check if interfered by other equipment and if interfered

possibly by the equipment like transmitting antenna, non professional radio station and cellular phone.

properly into the socket.

been switched on. ( as can be indicated by the red LED at the front of the TV set)

z See if it’s receiving the signal that is transmitted from

other source than the station

z Check if it’s connected to the wrong terminal or if the

input mode is correct.

z Check if the signal cable connection between video

frequency source and the liquid crystal TV set is correct.

z Check if all the picture setups have been corrected.

Symptoms Possible cause

Screen position or size is not

proper

Picture is twisted and deformed z Check to see if the picture-frame ratio is properly set up.

Picture color changed or colorless z Check the “Component” or “RGB” settings of the liquid

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)

Remote control cannot work properly

No picture and sound, but only

hash.

Blur picture z Check if the antenna cable is correctly connected.

No sound z Check if the “mute” audio frequency setting is selected.

When playing VHS picture search tape, there are lines at the top or bottom of the picture.

z Check is the screen position and size is correctly set up.

crystal TV set and make proper adjustment according to the signal types.

z Check if the contrast setting is too high. z Possibly the output quality of DVD broadcaster is set too

high.

z It maybe also due to improper terminal connection of the

video frequency signal in a certain position of the system.

z Check if the setting for the brightness is too high z Possibly the brightness grade of DVD player

(broadcaster) is set too high.

z Check if the cable is disconnected. z Check if it’s connected to the proper terminal or if the

input mode is correct.

z Check if the TV set can receive input signal. The signal is

not correctly identified and VGA format is beyond the specified scope.

z Check if the batteries are installed in the reverse order. z Check if the battery is effective. z Check the distance or angle from the monitor. z Check if there is any obstruct between the remote control

and the TV set.

z Check if the remote control signal- receiving window is

exposed to strong fluorescence.

z Check if the antenna cable is correctly connected, or if it

has received the video signal correctly.

z Of if it has received the right video signal.

z Check if the sound volume is set to minimum. z Make sure the earphone is not connected. z Check if the cable connection is loose.

z 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 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

Method of software upgrading

1. Connect RS-232 cable to computer and TV set. The cable must be a female to female RS-232

cable, and the line is TXD to RXD and RXD to TXD cross-link. It’s popular for PC to PC

connection.

2. If the computer has no RS-232 serial port(e.g. Notebook PC),you needs a additional USB to serial

port cable.

3. Copy the update tools (iDev.exe) to the path you want to do it, and double click it.

4. Select “setup” menu.

5. Confirm the Serial port is right. Base on the port which using for update. And set the band rate to

115200 (default).

6. Select the “Image path” menu.

7. Confirm it’s the right file.

8. If it’s not right(Maybe you didn’t select it before),click the “…”button to select “*.ecc” file. Sometimes

the image file you got it will be “*.rar ”or “*.zip” zip file, needs unzip it first.

9. You also can click the setup button to select and config, but please don’t select the red

one(update boot sector).

10. Then click the “down” button.

11. You can see the “waiting” window.

12. Then power (off then) on the TV set.

13. After download, it will be burning.

14. Last it will be finished

15. Press the (IR/ locate keypad) power key and holding for several second to force power off TV set,

then power on again. It would be ok now. If it’s failure you can try once again.

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