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Troubleshooting 

charts 

This series models adopt built-in power. The power to the main board may be different when the unit 

adopts different panels or whether the audio amplifier is located on the main board or not. The following 

is the detailed power in different cases. 

Model Audio 

amplifier 

Power socket 
number on the 
mainboard 

Definition of the pins (as follows, PBIAS 

refers to backlight ENABLE, PWM refers 

to backlight brightness control signal.) 

LC-20Y25 

LC-20Y15 

AN5277, locates on 

power board, Vcc=18V 

X702 

8 pin 

1, 2: +12V   3, 4: GND  5: +3.4V 

6: GND;     7: PBIAS   8: PWM 

LC-15Y3 TPA1517, locates on 

mainboard, Vcc=12V 

X701 

6 pin 

1, 2: GND    3, 4: +12V  

5: PBIAS     6: PWM 

LC-23Y25 AN5277, single audio 

amplifier, Vcc=18V 

X702 

1, 2, 3: +20V;          4, 5, 6: GND 

7: STANDBY            8: +3.3V 

LC-20Y3 AN5277, locates on 

mainboard, Vcc=18V 

X702 

1,2: +12V    3, 4: GND   5,6: +18V 

7,8: GND    9: PBIAS   10: PWM 

     

1. No raster, no picture and no sound 

When the main power is turned on, the unit’s indicator lights up in red (red indicator is controlled by 

+3.3VSTANDBY), use the remote control or the unit’s STANDBY to lights up the blue indicator.

 

 

Whether the IR
board’s red indicator
lights up? 

Power board’s +3.3V 

is abnormal

 

Whether the blue
indicator lights up 
when press the
STANDBY button? 

Confirm the IR 

sensor and its power 

supply is normal 

Indicator damages or blue 

ind9V power is 

abnormal (check +9V circuit)

Whether the 
backlight lights up? 

Whether the voltage 

of the panel is 

normal? 

8125

is abnormal without 

signal output or the output 

signal is abnormal

 

Whether the backlight
power or PBIAS pin is 

l

Backlight board damage or protection. 

Replace the backlight board 

Whether the
backlight power or
PBIAS pin is normal

 

Check power circuit or whether the 8125

PBIAS signal is normal

 

N

Y

Y

Y

N

Y

Содержание LC-20Y15

Страница 1: ...LCD TELEVISION LC Y LC 15Y3 LC 20Y15...

Страница 2: ...ading LC Y series working principle analysis Block diagram IC block diagram Main assembly Identification criteria for the bright spot and dark spot of the LCD screen Wiring diagram Troubleshooting cha...

Страница 3: ...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 mod...

Страница 4: ...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...

Страница 5: ...rd voltage to be 12v and 5v 3 3 main board adjustment 3 3 1 IF amplifier adjustment a Turn off the J201 J202 J203 J204 J205 and J5 input 38MHz PAL SYSTEM and 45 75MHz N Write memory N300 and N400 To p...

Страница 6: ...e1 Table1 Color temperature 9300K X coordinate 0 285 0 008 Y coordinate 0 293 0 008 g Repeat e step to f step it must be measure a true value h The unit without VGA interface of 20 N system you should...

Страница 7: ...uses 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 connect...

Страница 8: ...if the contrast setting is too high 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 s...

Страница 9: ...software upgrading The Y series models enable you to update software through the VGA interface Hardware requirements 1 One parallel cable with male end and female end 2 One standard VGA cable 3 The up...

Страница 10: ...close 4 Set the LCD to off Connect the Y updating board and PC with parallel cable 5 Connect the VGA MONITOR interface on the Y updating board with the VGA cable connect the other end to the VGA inter...

Страница 11: ...date the software next time you just need to click the pull down menu to select the desired Batch file and execute it in the following screen Note Do not cut off the power or turn off the unit during...

Страница 12: ...is sent to FLI8125 directly For the NTSC system when the RF signal is input to the NTSC tuner the turner generates IF signal Then the IF signals goes through the pre amplifying circuit and 45 75M SAW...

Страница 13: ...11 BLOCK DIAGRAM...

Страница 14: ...e inner IC block diagram and function 1 Inner block diagram of M52760 IF signal processing IC AFT QIF VIDEO OUT Descriptions of the pins Pin Description Pin Description 4 5 VIF input 13 QIF OUT 7 1ST_...

Страница 15: ...5V 31 VCC 9V power 3 R2S15900SP audio processor with surround stereo The audio signal from YPrPb YcrCb or VGA input interface is selective sent to R2S15900SP through the multi channel selector HEF4052...

Страница 16: ...nction Pin Function 2 7 Left right input for Channel 1 17 18 SDA SCL 3 26 Left right input for Channel 2 28 VCC 4 25 Left right input for Channel 3 11 19 LOUT ROUT 4 Inner block diagram of AN5277 audi...

Страница 17: ...15 5 Inner block diagram of TPA1517 6W stereo audio amplifier 6 Inner block diagram of FLI8125 digital video processing IC...

Страница 18: ...SEL_2 15 XTAL Resonator output 63 PBIAS Panel s oblique line control 16 TCLK Basic clock 64 PPWR Backlight adjustment 24 SCL_RS232 SCL_RS232 90 DEN Display data 25 SDA_RS232 SDA_RS232 91 DVS Display V...

Страница 19: ...30 40 One single spot 5 2 5 2 3 2 neighboring spots 2 1 2 1 1 Bright spot Total No 5 2 5 2 3 15mm One single spot 6 7 5 4 10 Two neighboring spots 2 2 2 1 5 Dark spots Total No 6 7 5 4 10 15mm 10mm 5...

Страница 20: ...18 Wiring diagram Button board B Button board A Right speaker Left speaker Back light board Power board Main board indicator light board...

Страница 21: ...ainboard Vcc 18V X702 1 2 12V 3 4 GND 5 6 18V 7 8 GND 9 PBIAS 10 PWM 1 No raster no picture and no sound When the main power is turned on the unit s indicator lights up in red red indicator is control...

Страница 22: ...ent from the actual frequency Connect the signal cable manually adjust the frequency to conform to the actual frequency Enter into service menu check AFT value should be about 1 6V If the difference i...

Страница 23: ...k whether N901 D501 breakdown Replace N501 D501 Check whether C512 has 18V Replace D502 Check whether pin1 of N501 has wave Replace N502 Check whether N502 is damaged Replace N505 Check whether N505 i...

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Страница 30: ...LC 20Y15...

Страница 31: ...LC 20Y15...

Страница 32: ...LC 20Y15...

Страница 33: ...LC 20Y15...

Страница 34: ...LC 20Y15...

Страница 35: ...LCD S M LC Y L15Y3 and L20Y15 Ver 1 0...

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