Daytek lc1508nt, lc2018nt schematic

LCD TV SERVICE MANUAL

Model list

LC1508NT

LC1521NT

LC2018NT

DAYTEK

Digital Flat Display Division

IMPORTANT SERVICE SAFETY INFORMATION

Operating the receiver outside of its cabinet or with its back removed involves a shock hazard. Work on these

models should only be performed by those who are thoroughly familiar with precautions necessary when working on

high voltage equipment.

Exercise care when servicing this chassis with power applied. if carelessly contacted, can cause serious shock or

result in damage to the chassis. Maintain interconnecting ground lead connections between chassis, escutcheon, picture

tube dag and tuner when operating chassis.

When it is necessary to make measurements or tests with AC power applied to the receiver chassis, an Isolation

Transformer must be used as a safety precaution and to prevent possible damage to transistors. The Isolation

Transformer should be connected between the TV line cord plug and the AC power outlet.

It is important to maintain specified values of all components and anywhere else in the received that could cause

a rise in operating supply voltages. No changes should be made to the original design of the receiver.

Components shown in the shaded areas on the schematic diagram and/or identified by in the replacement parts

list should be replaced only with exact factory recommended replacement parts. The use of unauthorized substitute

parts man creates may create shock, fire, or other hazards.

Before returning the receiver to the user, perform the following safety checks:

1. Inspect all lead dress to make certain that leads are not pinched or that hardware is not lodged between the chassis

and other metal parts in the receiver.

2. Replace all protective devices such as non-metallic control knobs, insulating fish papers, cabinet backs, adjustment

and compartment covers of shields, isolation resistor-capacitor networks, mechanical insulators etc.

3. To be sure that not shock hazard exists, a check for the presence of leakage current should be made at each exposed

metal part having a return path to the chassis (antenna, cabinet metal, screw heads knobs and/or shafts, escutcheon,

etc.) in the following manner.

Plug the AC line cord directly into a 110V/220V/240V, AC receptacle. (Do not use an Isolation Transformer

during these checks.) All checks must be repeated with the AC line cord plug connection reversed. (If necessary, a

non-polarized adapter plug must be used only for the purpose of completing these checks.)

PLEASE READ BEFORE ATTEMPTING SERVICE

1. Use an Isolation Transformer when performing any service on this chassis.

2. Never disconnect any leads while receiver is in operation.

3. Disconnect all power before attempting any repairs.

4. Do not short any position of the circuit while the power is on.

5. For safety reasons, replace components any with identical replacement parts (SEE PARTS LIST).

6. Before alignment, warm up the TV for at least 30 minutes.

7. When removing a PCB or related component, after unfastening or changing a wire, be sure to put the

wire back in its original position.

8. Inferior silicon grease can damage IC's and transistors. When replacing IC's and transistors, use only

specified silicon grease. Remove all old silicon when applying new silicon.

9. Before removing the anode cap, discharge eletricity because it contains high voltage.

A. SPECIFICATION

System : NTSC-M
Channel : Antenna 2-69
CATV 1-125
IF Frenquency Video： 45.75MHz
Sound： 42.17MHz
Chroma： 41.25MHz
Audio output power 10%THD 1W X 2
Antenna Impedance 75Ω(Unbalance)
Power Consumption 36W
Power Supply : AC~100-240V,50/60Hz (Adapter)
DC12V 3A（TV）

item Port list （KLC-1508US）

1 RF cable
2 Video and Audio
3 S-Video
4 Headphone audio output
5 DC 12V input

item Port list （KLC-1521US）

1 RF cable
2 Y 、Pb /Cb、Pr /Cr
3 Audio2(Y、Pb/Cb、Pr/Cr Audio input)
4 VGA
5 Audio3（PC Audio input）
6 Video and Audio1
7 S-Video
8 Headphone audio output
9 DC 12V input

ADJUSTMENT MANUAL

Ⅰ. TEST NOTE

1. Please follow the pointed test steps and choose the right test equipment to conduct

adjustment, otherwise good effect of Unit could not be obtained. The unit should be
warmed up for 30 minutes before adjustment and every parameter should be adjusted
repeatedly till the optimum value obtained, the pointed voltage value should be ensured
during test to get satisfied test result.

2. Test environment

1) Temperature ： 15°C-35°C

2) Relative Humidity : 45-75%

3) Air pressure : 86-106KPa

3 Test equipments（The following equipment should be calibrated before testing）

1) Computer 1 set

2) Multi-meter (VICTOR VC9801) 1 set

3) Video Signal Generator (Chroma Model 2227/2327) 1 set

4) Color Analyzer (Chroma Model 7120 ) 1 set

5) DDC card (DYNACOLOR, INC D8330) 1 slice

6) TV Video Signal Generator (FLUKE PM54200) 1 set

4 Factory mode adjustment

4.1 Enter factory mode adjustment
Using the remote control, press Menu button once first , then press PRE.CH(or named
RECALL) button five times,and you can see manufacture menu on the LCD panel.

4.2 factory menu operation method
Press the channel +/- button to selection the sub menu of factory menu（including F、E、
UOCⅢ、RGBTemp、Temp）, and press the vol+ to enter the sub menu and setting the value.

4.3 exit the factory menu
Press the MUTE button again and again or turn off the TV, it can exit the factory menu.

4.4 AGC adjustment
In TV mode,Receive 60dB split field signal.Enter factory mode menu “UOCⅢ ” item,
press”CHAN▽” to select “RF AGC” ，then use VOL+/- to adjust the item until the voltage of Pin
1 of N100 to be about 2.5V±0.2V,then noise wave of the picture point disappears.

4.5 White calibration adjustment

CVBS,S

-

Video

PWRON

DDC/HWI2C

BKLON

VCC

-

5Ua VCC

-

3.3VUSB

VCC+1.8a

VCC+1.8b

TDA1517

UOC_R,G,B

Y_G

DDC/HWI2C

To N401

SDA

SCL

VGA

-

DAT VGA

-

CLK

VGA_R,G,B

VGA_Hs,Vs

VCC

-

PAN

(Only for KLC

-

1521US)

1 Receive black or white signal under AV or PC mode, adjusting brightness and contrast to set
the brightness to 15Nit in dark area and 90 Nit in bright area.
2 Adjust white balance.Press“MENU”button once, then press “PRE.CH”five times to enter
factory menu, select “Temp” Menu,
Adjust Red 0-100
Green 0-100
Blue 0-100

3 Adjusting chromaticity coordinates of black and white to fit the requirement (X=0.285,
Y=0.293), or plug automatic calibration system to adjust white calibration automatically.

BLOCK DIAGRAM

Signal Block Diagram

N100
Tuner

+12V
Supply

Earphone

speaker

Port

VG
A

AGC

port
Y
Pb
Pr

T101
M3953

T102
M9352

Audio
N201

+12V
Supply

Audio 2
L,R

Y,Pb/Cb,Pr/Cr

VGA
Audio IN

VIF

SIF

AMP_L

AMP_R

AU2IN_L,R

AU3IN_L,R

Audio L,R

TDA15001H

N303

PI5V330

Pb_B
Pr_R

N301

PI5V330

N401

MAIN IC

YUVHs
YUVVs

N501

MST518

M_Rst
M_CLK
M_SDA
M_CS

LED R,G

KEY B1、B0
IR

LCD

PANEL

3.3V Supply

2.5V Supply

N302

24LC21