XOCECO LC-37T25 SERVICE MODE AND TROUBLE SHOOTING

XOCECO LC-37T25 SERVICE MODE AND TROUBLE SHOOTING

XOCECO LC-37T25

LCD TV SERVICE MODE AND TROUBLE SHOOTING

SERVICE MODE

Method for entering factory menu: press “VOL+”, “MUTE” and “VIDEO” repeatedly to enter factory menu; press “ENTER” to select different items.

EEPROM initialization
Enter the first page of factory menu, select “clear eeprom” and then press “enter”, shut down the unit after “ok” appears.

Trouble shooting

Picture is out of focus or jumping

1.Bad status in signal receiving
2.Poor signal
3.Check if there are failures with the electrical connector or the antenna.
4.Check if the antenna is properly connected.

Fringe in picture

1.Check if the antenna is correctly oriented.
2. Maybe there is electric wave reflected from hilltop or building.

Picture is interfered by stripe shaped bright spots

1.Possibly due to interference from automobile, train, high voltage transmission line, neon lamp etc.
2.Maybe there is interference between antenna and power supply line. Please try to separate them in a longer distance.
3.Maybe the shielded-layer of signal wire is not connected properly to the connector.

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.

Unable to switch the power on

Check to see if the power plug has been inserted properly into the socket.

No picture and sound

1.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)
2.See if it’s receiving the signal that is transmitted from other source than the station
3. Check if it’s connected to the wrong terminal or if the input mode is correct.
4.Check if the signal cable connection between video frequency source and the liquid crystal TV set is correct.

Deterioration of color phase or color ton

Check if all the picture setups have been corrected

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 distortion in the brightest area

1.Check if the contrast setting is too high.
2.Possibly the output quality of DVD broadcaster is set too high.
3. 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 the displayer if “XXX in search” appears.

1.Check if the cable is disconnected.
2, Check if it’s connected to the proper terminal or if the input mode is correct.

There appears 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

1.Check if the batteries are installed in the reverse order.
2.Check if the battery is effective.
3. Check the distance or angle from the monitor.
4. Check if there is any obstruct between the remote control and the TV set.
5.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.

Blur picture

Check if the antenna cable is correctly connected, or if it has received the video signal correctly.

No sound

1.Check if the “mute” audio frequency setting is selected.
2.Check if the sound volume is set to minimum.
3. Make sure the earphone is not connected.
4.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 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.

WORKING OF LC-37T25 
RF signal produces composite color television signal through TUNER201, the signal together with AV1/SVHS(SVHS priority) and AV2 etc. are sent to U29 VPC3230D to decode and do switching selection. In addition to decode the selected video signal, part of the selected video signal is also sent to AV terminal and 21 line decoder U32 Z86229 which is exclusive to decode CCD/V-CHIP to decode. After decoded by U32, the signal will be sent back to U29 in the form of R G B and FB, then it will be added to the decoded picture and then it will be sent to U13 FL12310 in the form of ITU-R656 signal format of 8BIT to do line-by-line process. Send two ways YPRPB signal to U30 MST9883 through selection by N2 PI5V330 in order to do the A/D conversion. After this, the signal will be converted into YUV signal of 24BIT, send it to FLI2310 also.

After a series of procedure such as matrix, chroma and tint etc. by FL12310, the two ways signal will be converted into RGB of 24bit, then send it to the main processing chip U12 JAG-ASM. send RGB signal it to the main processing chip U12 at the same time. There has another signal which should be sent to U12 together with he above two kinds of signal that is: RGB signal of 24BIT produced by DV1 through U15 TFP403/501. Do the picture format processing for the three kinds of signal in U12. Firstly do the A/D conversion for RGB signal of VGA, then do the switching selection together with the other two kinds of signal. And then they will be converted into 1024*768 format through digital display processing such as OSD and GAMMA correction etc. output it in the form of 24BIT RGB signal. Send it to LVDS convertor U31 DS90C383A, then it will be converted into signal format which can be accepted by LCD screen namely 3 low-voltage differential signal and 1 clock signal, finally send it to LCD screen to do the picture display PWM of U12 can also be used to control the brightness of back light-source. Send SIF (the second IF) outputted by tuner to audio processor NA01 MSP3420; send YPRPB and audio signal of DVI to NA01 through switching selection by U34 HEF4052; Send AV1/SVHS, AV2 and audio signal of VGA to NA01 also. Firstly SIF will be done the switching selection together with another four ways of audio signal, finally volume control and sound effect processing will be done. Output left-right sound channel signal R/L. one will be sent to SRS sound field processor NA03 M62494 to do SRS processing and finally amplified by NA03 and NA04 TPA3008D2 to drive the speaker, one will be used to drive the headphone through NA02 TLE2142 and the last part will be outputted as R/L of AV OUT