How to enter service mode_Adjustments_Checking procedure_Power Supply Regulator Circuit Diagram_ DAYTEK LC1508NT LC1521NT LC2018NT
> To 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.
> 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.
> Press the MUTE button again and again or turn off the TV, it can
exit the factory menu.
ADJUSTMENT ITEMS
* AGC adjustment In TV mode,Receive 60dB split field signal.Enter
factory mode menu “UOC Ⅲ” 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.
* White calibration adjustment 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.
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
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.
START ORDER
Turn on the power > N401 RESET and IO port initialize >
N501electrify, reset, initialize > Turn on back light lamp > Successful
start and LCD display
CHECKING
1 Verify the state of TV set. Switch the TV on ,then verify the
LED color. Red is standby state and green is working state.
2 Checking Supply Power. If the color of LED is yellow, the power
supply for signal board. N801 supply 5V
and N802 supply 3.3V(KLC-1508US,KLC-1521US),N804、 N806 supply 3.3V power(Test the PIN 2).N805 supply 2.5V(Test the
PIN 2),D803 supply 8.3V,V401 and V402 supply 1.8V. All these are for main I
CN401, N501
3 After turning on the power, if blank screen appears (no back
light lamp), just press POWER button several times, if blank screen still there.
Check if the voltage of power supply is normal.
4 Check if the crystal oscillator X501(14.318180MHz)
X401(24.576MHz) oscillate or not, and oscillate frequency is right or not.
5 Back light control signal (BKLON) of XS801 has high level (about
2.5V) or not, if not, check whether fault soldered or short circuit happened。
6 If back light lamp is on while there is no display, check N407
and N501’s reset circuit and the output of the oscillator to confirm the CPU
and SCALER are working or not. If RGB is abnormal, check N501; If RGB is
working correctly and the other channel is abnormal, check N501.
SMPS SCHEMATIC [Circuit Diagram]
Click on the circuit diagram to Magnify
