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LCD TELEVISION
LC-27U16
CONTENTS
Safety instructions...................................................................................... 1
Adjustment instructions .............................................................................. 3
Trouble shooting ........................................................................................6
Working principle analysis.............................................................................8
Block diagram........................................................................................... 9
IC block diagram.........................................................................................10
Identification criteria for the bright spot and dark spot of the LCD screen............... 22
Wiring diagram ......................................................................................... 23
Troubleshooting charts................................................................................ 24
Schematic diagram ........................................................................................ 27
APPENDIX: Main assembly
Exploded View
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
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.
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.
2
Alignment instruction
1 Alignment equipment
PM5518 (video signal generator)
K-7253 (VGA signal generator)
CA210 (white balancer)
2 Alignment flow-chart
The alignment flow-chart is shown as fig-1
Check DDC, HDCP KEY and CPU
Factory initialization setup
IF channel voltage of TV and AGC voltage adjustment
Support format of VGA pre-set
Adjustment for sub-brightness and white balance of VGA/HDMI (color
temperature 6500k, 9300k and 12000k)
Adjustment for sub-brightness and white balance of YPbPr/YcbCr channel
Adjustment for sub-brightness and white balance of VIDEO channel
Preset ex-factory
Fig-1 adjustment flow-chart
3 Unit adjustments
Connect digital board, CPU board and analog board according to wiring diagram, connect with
power and observe the display.
Method for entering factory menu: press "SLP", "DSP", "MENU" and "DSP" in turn to enter factory
menu; press "CH+" and "CH-" to select adjustment items and press "VOL+" and "VOL-" to adjust
value items, press "MENU" to exit.
Note: the white balance adjustment should be done under "nature" picture mode.
3.1 Initialization
Enter factory menu, select "Factory settings" sub-menu, and adjustment for items of table1.
3
Table1 sub-menu adjustment
Items Range Introduce
PW on LOGO ON/OFF Display 5s LOGO of turn on the TV
NO Sig LOGO ON/OFF If display LOGO in no signal
Black Screen BLUE/BLACK If display blue screen and white noise wave in no signal, setting
"BLUE"
MLK 120-159 Adjustment for clock frequency (MHz) of memorizer, setting "145".
PIP Size Middle/Large Select two component of PIP: "SMALL AND MIDDLE" and "SMALL
AND BIG", setting "MIDDLE".
init EEprom Start? Eeprom Initialization (adjustment for EEprom data)
3.2 Adjustment for AFT voltage and AGC voltage of IF channel in TV
Input frequency for 45.75MHz and IF signal for 80dBV of TP1, adjust L107 to value 2.4v of TP2;
when increase 0.10MHz of TP1 input signal, the TP2 value 1.0v at least; but decrease 0.10MHz of
TP1 input signal, the TP2 value 4.0v at least.
3.3 VGA/DVI channel adjustment
3.3.1 Preset VGA channel mode
Input VGA signal (PATTERN: CROSS) of VG-849 or VG-848, select PROG850(640*400/85Hz),
auto adjustment until the screen is filled with picture. Use the same method to do auto adjustment
for the following items:
PROG851(640*480/72 Hz) PROG852(640*480/75 Hz) PROG853(800*600/56 Hz)
PROG854(800*600/60 Hz) PROG855(800*600/72 Hz) PROG856(1024*768/60 Hz)
PROG857(1024*768/70 Hz) PROG858(1280*768/75 Hz) PROG888(800*600/75 Hz)
PROG915(1152*870/75 Hz) PROG915 (1280*1024/60Hz)
3.3.2 Sub-brightness and White balance adjustment VGA/HDMI channel
a. Input VG-849 or VG-848 signal of VGA: PROG852(640* 480/75Hz) and eighth level gray-scale
signal of PATTERN. Use color analyzer CA210 to adjust sub-brightness and white balance.
b. Enter submenu of COLOR TEMP., Select 9300k of color temperature, set auto value of R, G and
B to 50. Enter submenu of white balance, preset value of offset_R, offset_G and offset_B to 125,
and preset value of gain-R, gain-G and gain-B to 100. Adjustment for brightness let the second level
brightness be 3nit at least.
c. Fixed value of offset_B, adjust offset_R and offset_G, let the color coordinate of the second level
be 285 and 293 and its brightness be 4-5nit more or less (it can not 3.5nit at least). Fixed value of
gain_B, adjust gain_R, gain_G and gain_B, let the color coordinate of seventh level be 285 and 293.
Adjustment offset_R, offset_G, offset_B, gain_R, gain_G and gain_B repeatedly until the value of
the two levels gray-scale be 285 and 293.
d. Select 6500k of color temperature, set auto value of R, G and B to 50. Fixed value of B to 50,
adjust R and G, let the color coordinate of the sixth level be 313 and 329. Adjust R and G repeatedly
until the color coordinate value to 313 and 329.
e. Select 12000k of color temperature, set auto value of R, G and B to 50. Fixed value of B to 50,
adjust R and G, let the color coordinate of the sixth level be 270 and 283. Adjust R and G repeatedly
until the color coordinate value to 270 and 283.
4
f. Input PROG852(640*480/75Hz) and the eighth level gray-scale of PATTERN signal of VG-849 to
HDMI, repeatedly the b-e course. In the HDMI channel, preset value of offset_R, offset_G and
offset_B to 15, preset value of gain_R, gain_G and gain_B to 25.
3.4 Adjustment for sub-brightness and white balance of YPbPr channel
a. Connect YPbPr signal of VG-849 and VG-848 to YPbPr terminal, input color signal of
PROG973(1080i)PATTERN964. Select AUTOTUNE item, wait for it displays "OK". NOTE: Don't
select AUTOTUNE item in other state.
b. Switch YPbPR signal of VG-849 and VG-848 output to the eighth gray-scale signal of
PROG973(1080i)PATTERN964. prset value of offset_R, offset_G and offset_B to 15 and gain-R,
gain-G and gain-B to 25. adjust brightness, let second bright to 3nit at least.
c. Fixed value of offset_B, adjust offset_R and offset_G, let the color coordinate of the second level
be 285 and 293 and its brightness be 4-5nit more or less (it can not 3.5nit at least). Fixed value of
gain_B to 25, adjust gain_R, gain_G and gain_B, let the color coordinate of seventh level be 285
and 293. Adjustment offset_R, offset_G, gain_R and gain_G repeatedly until the value of the two
levels gray-scale be fixed.
d. Input PROG977(720p), PROG978(480p) and PROG968(480i) mode for eighth level gray-scale
signal, let the color coordinate of the second level and the seventh level 285 and 293.
3.5 VIDEO channel adjustment (TV/VIDEO/S-VIDEO)
a. Connect color bar signal of AV (PM5518, NTSC , eight level gray-scale signal) to VIDEO1
terminal, enter factory menu, preset value of offset_R, offset_G and offset_B to 15 and gain-R,
gain-G and gain-B to 25, adjust brightness, let second bright to 3nit at least.
b. Fixed value of offset-B to 15, adjust offset_R and offset_G, let the color coordinate of the second
level be 285 and 293 and its brightness be 4-5nit more or less (it can not 3.5nit at least). Fixed value
of gain_B to 25, adjust gain_R, gain_G and gain_B, let the color coordinate of seventh level be 285
and 293. Adjustment offset_R, offset_G, gain_R and gain_G repeatedly until the value of the two
levels gray-scale be fixed.
4 Performance check
4.1 TV function
Enter searching menu auto search, connect RF-TV terminal with central signal source and check
if there are channels be skipped
4.2 AV/S, YpbPr terminals
Input AV/S, HD signal, check if it is normal.
4.3 VGA terminal
Insert VGA terminal, input VGA format signal of 640 X 480@60 Hz, check if the display is normal. If
interference exists, press the auto adjusts button on remote control again and check if it is normal.
4.4 HDMI terminal
Insert HDMI terminal, input signal of 640 X 480@60 Hz signal and check if the display is normal.
4.5 check sound channel
Check the speaker and headphone of each channel.
4.6 presetting before ex-factory
5
Item Setting Item Setting Item Setting
Picture mode NATURE OSD language English CCD OFF
Sound mode NORMAL HALFTONE 50 STEREO ON
N/R WEAK DURATION 30 VGA/HDMI NORMAL
SCREEN FULL MAG.C ON ANTENNA CATV
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 Bad status in signal receiving
Poor signal
Check if there are failures with the electrical connector or
the antenna.
Check if the antenna is properly connected.
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 Possibly due to interference from automobile, train, high
shaped bright spots 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.
Maybe the shielded-layer of signal wire is not connected
properly to the connector.
There appear streaks or light color Check if interfered by other equipment and if interfered
on the screen 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 the signal cable connection between video
source and the liquid crystal TV set is correct.
6
Deterioration of color phase or color Check if all the picture setups have been corrected.
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 and make proper adjustment
according to the signal types.
Picture too bright and there is Check if the contrast setting is too high.
distortion in the brightest area Possibly the output quality of DVD broadcaster is set
too high.
It maybe also due to improper terminal connection of
the video 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 Check if the cable is disconnected.
displayer if "XXX in search" appears. Check if it's connected to the proper terminal or if the
input mode is correct.
There appears an indication - "outside Check if the TV set can receive input signal. The
the receivable scope) 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 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 When being played or in pause VHS picture search
tape, there are lines at the top or tape sometimes can't provide stable picture, which
bottom of the picture. may lead to incorrect display of the liquid crystal TV,
In this case please press "auto" key on the remote
7
control so as to enable the liquid crystal TV set to
recheck the signal and then to display correct picture
signal
Working principle analysis
RF signal from the antenna to tuner, via high frequency amplifier and mix frequency to obtain IF
signal, and then via pre-IF amplifier in V104, then it send to processed IF filter of SAW (Z103),
obtain more idea IF speciality, it processed to IF amplifier, phase locked logic VCO and sync
detection of N101 (M52760E) in the TV board to obtain VIDEO; IF via pre IF amplifier to send to
processed filter of SAW (Z102), again send to processed IF amplifier of N101, decode second SIF.
From M52760E output VIDEO, AV1 and AV2/S signal all send to video decoder N601
(TVP5160), via video select, clamping, A/D transfer, comb filter and color decode, one way
output AV OUT, another way output 8bit for CIR656 format signal and CLK signal, send to
N101(MST6151) of CPU board, Also YPbPr, VGA and HDMI send to N101. N101(MST6151) is
many function big dimension integrate circuit, it processed HDMI, A/D to DA switch, interlaced and
non-interlaced processing, model switch and low voltage difference output functions and so on, it
send to four ways difference signal and one way clock signal to LCD display.
From HDMI input to MST6151contain sound signal, via processed MST6151, send to processed
D/A switch for NA01(CS4340), output L/R of HDMI.
Output SIF from M52760F and send to processed stereo demodulation for N201(LA72700), output
L/R of TV.
L/R of HDMI and Ypbpr from CS4340 output, L/R of VGA/DVI signal via sound switch
NA02(HEF4052) to select, then send to sound processing N301(R2S15900SP); demodulate L/R
signal of LA72700 send to N301, and L/R signal for AV1A and V2/S input send to N301. Via
selected switch and processing sound, one way sound output for AV OUT, other way send to
N401(TPA3008D2) of sound amplifier, via amplify for sound signal to speaker and earphone.
The unit working is controlled N801(MM502) of CPU, connect tuner, TVP5160, LA72700 and
R2S15900SP to IIC bus; connect MST6151 to parallel BUS.
8
BLOCK DIAGRAM
AV1-A AV2/S-A
YPbPr-A AUDIO
VGA/DVI-A SW L/R
HDMI-A NA02 AUDIO
SIF DEC L/R AUDIO AMP
HEF4052 PROCESSOR
N201 N401
N301
LA72700 TPA3008D2
R2S15900SP
A
AV OUT L/R
SIF
SAW
RF Z102 IF AMP
TUNER SPEAKER
IF N101(TV)
SAW M52760E
Z103 V HEADPHONE
V IIC
VIDEO1 VIDEO
SCALER
Y/VIDEO2 DECORDER CCIR656 A/D D/A
C N601 8bit DEINTERLACER
TVP5160
LVDS PANEL
YPbPr HDMI
VGA
HDMI/DVI N101(CPU)
DAC MST6151DA
HDMI-A NA01
L/R CS4340
BUS SDRAM SDRAM
N201 N202
EEPROM
N802 MCU
N801
EEPROM MM502
N803
9
IC block diagram
TVP5160
10
M52760
2: AFT
3: AGC
4, 5: picture If input
7: sound IF input
13: SIF output
10: mono sound output
18: TV- VIDEO output
14, 17: +5V-1 power supply
11
LA72700
5: SIF input
25: TV sound -R output
26: TV sound- L output
11: SDA
12: SCL
31: +9Vpower supply
12
MST6151
207, 208: HDMI-R input
2, 3: HDMI-G input
5, 6: HDMI-B input
8, 9: HDMI-CLK input
14: HDMI-SDA
15: HDMI-SCL
20, 21: VGA-B input
22: VGA-G input
23, 24: VGA-G input
25, 26: VGA-R input
18: VGA H-sync input
19: VGA V-sync input
27, 28: PB input
29, 30: Y input
31: HDMI-G input
32, 33: PR input
54-61: CCIR656 format signal input
53: CLK input
164-171, 174: 4 difference signal output
160, 161: 1 clock signal output
188-191: HDMI sound output
200: PWW (brightness control switch) output
72-75: BUS (parallel communication signal)
49, 131, 195: 1.8V power supply
4,17,12,109,204,66,102: 3.3V power supply
13
PIN DIAGRAM (MST5151A)
AVDD_MPLL
AUMUTE
LVBCKM
LVACKM
DVI_R+
BYPASS
LVBCKP
LVACKP
SPDIFO
AUMCK
DVI_R-
LVB0M
LVB1M
LVB2M
LVB3M
LVA0M
LVA1M
LVA2M
LVA3M
AUSCK
AIMCK
LVB0P
LVB1P
LVB2P
LVB3P
LVA0P
LVA1P
LVA2P
LVA3P
PWM1
PWM0
AISCK
AUWS
VDDC
VDDC
VDDC
VDDP
VDDP
AUSD
XOUT
AIWS
AISD
GND
GND
GND
GND
GND
GND
GND
GND
GND
XIN
208
207
206
205
204
203
202
201
200
199
198
197
196
195
194
193
192
191
190
189
188
187
186
185
184
183
182
181
180
179
178
177
176
175
174
173
172
171
170
169
168
167
166
165
164
163
162
161
160
159
158
157
GND 1 156 VDDC
DVI_G+ 2 155 GND
DVI_G- 3 154 VDDM
AVDD_DVI 4 Pin 1 153 DQS[0]
DVI_B+ 5 152 MDATA[0]
DVI_B- 6 151 MDATA[1]
GND 7 150 MDATA[2]
DVI_CK+ 8 149 MDATA[3]
DVI_CK- 9 148 MDATA[4]
AVDD_DVI 10 147 MDATA[5]
REXT 11 146 MDATA[6]
AVDD_PLL 12 145 MDATA[7]
GND 13 144 MDATA[8]
DDCD_DA 14 143 MDATA[9]
DDCD_CK 15 142 MDATA[10]
GND 16 141 MDATA[11]
AVDD_ADC 17 140 GND
HSYNC1 18 139 VDDM
VYSNC1 19 138 MDATA[12]
BIN1P 20 137 MDATA[13]
BIN1M 21 136 MDATA[14]
SOGIN1 22 135 MDATA[15]
GIN1P 23 134 DQS[1]
GIN1M 24 133 DQM[0]
XXXXX
XXXXXXXXXXX
MST5151A
RIN1P 25 132 GND
RIN1M 26 131 VDDC
BIN0M 27 130 MADR[11]
BIN0P 28 129 MADR[10]
GIN0M 29 128 MADR[9]
GIN0P 30 127 MADR[8]
SOGIN0 31 126 GND
RIN0M 32 125 VDDM
RIN0P 33 124 MADR[7]
AVDD_ADC 34 123 MADR[6]
GND 35 122 MADR[5]
HSYNC0 36 121 MADR[4]
VSYNC0 37 120 MADR[3]
RMID 38 119 MADR[2]
REFP 39 118 MADR[1]
REFM 40 117 MADR[0]
VI_DATA[8] 41 116 WEZ
VI_DATA[9] 42 115 CASZ
VI_DATA[10] 43 114 GND
VI_DATA[11] 44 113 VDDM
VI_DATA[12] 45 112 RASZ
VI_DATA[13] 46 111 BADR[0]
VI_DATA[14] 47 110 BADR[1]
VI_DATA[15] 48 109 AVDD_PLL2
AVDD_APLL 49 108 GND
GND 50 107 MCLK
GPO[5] 51 106 MCLKZ
GPO[4] 52 105 MCLKE
100
101
102
103
104
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
VI_DATA[0