Service Manuals, User Guides, Schematic Diagrams or docs for : . Various CHINA TV LCD lc_37t18_37t26_929
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LCD TELEVISION
LC-37T26/18
CONTENTS
Safety precautions...................................................................................... 1
Alignment instructions .............................................................................. 3
Working principle analysis of the unit...............................................................6
Block diagram.............................................................................................8
IC block diagram.........................................................................................9
Wiring diagram ............................................................................................
17
Troubleshooting............................................................................................
18
Schematic diagram .................................................................................... 25
APPENDIX: 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 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
1
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 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
Digital multimeter, signal generator (54200)
PC set (FLASH writing programs and W24CXX.EXE have to be installed first,)
VG849 (HDMI signal generator)
CA210 (White balancer), DVD player(with HDMI output), monitor
2. The alignment flow chart (see below Fig.1)
Write N105, N403, N607, N70, N606
To produce main board, TV board and other board
Check the TV board
Check accessories and then packing
Check the MAIN board
Input VGA signal source, check is the display is
normal in PC state and various function (analog
control) H-V center etc. The AV-out output sound
Check the buttons board and IR receive board is originally signal
Combined test for general assembly
Input HDMI and DVI signal source, check if
the HDCP KEY is normal. The AV-out output
sound is originally signal
Aging
Input YPbPr/YCbCr 1/2 signal source; check if
the picture and sound analog control is normal in
the COMPONENT state. The AV-out output sound
ADC correction and white balance adjustment
is originally signal
Input the center signal source, check if various Input AV1/S/AV2 signal source, check if the
functions of TV (search channel, system identify various terminal functions (system identify and
and analog control etc.), earphone output, speaker analog control etc.) and the picture and sound of
output and the picture and sound of AV-out is AV-out is normal. (S-terminal shares the same
normal. (check stereo/SAP, CCD and VCHIP for audio channel with AV1, and it can be auto
American unit) identified)
Fig.1 Flow process of alignment
3
3. Alignment instructions
3.1 flash write programs
Flash write N606, N607, N105, N403, N701
Flash write W24CXX.EXE into N102 with self-made flash write tool on the line.
Note: N606 may upgrade from the socket X1
N701 may upgrade from the serial wire
N102, N403 may upgrade from HDMI and VGA interface respectively
N105 can not upgrade on the line, so ensure HDCP KEY is right
3.2 the main board adjustment
a. Connect the X602 of main board to the infrared receive board, the supply power plug to X1, then
the indicator of the infrared receive board is red light.
b. Press the POWER button; the indicator change to blue light, the LED1 of main board is flicker of
slow.
c. Write EDID program to N102
d. Check if various channels are normal.
3.3 The TV board adjustment
a. Connect the high frequency board to main board, and connect the X501 and X502 to the supply
power.
b. Press the POWER button, the indicator change to blue light.
c. Check if the picture and sound of TV/AV1/AV2/S/YPBPR1/YPBPR2 and sound of HDMI/VGA
channels are normal. Check the STEREO and SAP. Check AV-OUT function: the picture and
sound of AV-OUT should be the picture and sound of the current channel at TV/AV1/S/AV2, at
other signal source, the sound of AV-OUT should be the sound of the current channel, but the
picture don't need to check.
3.4 the unit adjustment
After install the unit, check it is normal working.
3.5 Aging
a. Select the TV channel, the screen is noise wave of no signal TV
b. Aging an hour.
3.6 ADC correction and white balance adjustment (use white balancer CA210 and signal generator
VG849)
Enter the factory menu method: press "1" "9" "7" "9" button in the window menu state
a. Enter VGA channel,input 16 level gray signal of 1024*768@60Hz(TIMING:889, PATTERN:921).
b. Enter PICTURE menu, set "Color Temp" to "Middle"
c. Enter the factory menu, press AUTO ADC CALIBRATION and operate according the prompt.
d. Input 8 level gray signal of 1024*768@60Hz and test the fourth level with CA210, adjust the
brightness until the brightness value of CA210 is 180◦ Jabse Service Manual Search 2024 ◦ Jabse Pravopis ◦ onTap.bg ◦ Other service manual resources online : Fixya ◦ eServiceinfo