Service manual

switch into LVDS signal to send it to PANEL for processing.
3、flow of main video signal process：
CVBS composite video signal of TUNER (including TUNER signal) and S-VIDEO signal
is output to PW106 of SCALER board via 2069 of IO board.
PW106 handles with the input video signal, such as resolution and field switch,
OSD overlapping, multi-window handling, to switch into PANEL-required resolution.
And LVDS channel transports the picture data to PANEL and finally the correct
picture is displayed on PANEL.
It should be noted that PW106 outputs analog video signal and the main transport
mode is difference transport mode. Therefore, when maintenance, not only‘+’
signal but also ‘-’signal of all video channels should be checked.
4、Flow of audio signal process:
Most of audio signals are processed on I/O board, while SCALER board only
processes the audio signal from HDMI. Because HDMI accepts the HD digital signal
input, its audio input should be digital signal, which is switched into analog audio
signal via WM8761. Then the processed analog audio signal is sent to IO board for
amplifying.
5、Flow of main system program
The loading program of PW106 is saved in the 8M flash chip. If the flash chip
is destroyed, TV can’t be powered on and logo can’t be displayed.
The program upgrading of FLASH can be done via the upgrading port of SCALER
board or IO board, as long as the power supply and FLASH and PW106 are normal.
It has nothing to do with DDR chip.
The running of PW106 depends on two DDR chips. If part of DDR circuit is
abnormal, then TV can be powered on and logo can be displayed, but TV doesn’t accept
any IR order once logo disappears.
6、Some other controls
For LCD PANEL， besides PW106 transporting LVDS signal to PANEL, it also: 1/.
suppliers power （LVDSVDD）to signal port of PANEL. The voltage is 5V or 12V,
which is up to the PANEL requirement; 2/. Controls the backlight of PANEL:
BKL-ON/OFF，which controls the On/Off of backlight of PANEL（above 1V=On，below
1V=Off），while BRT-ADJ controls the brightness of backlight.
When TV can’t display, it should be checked first if the backlight is on. If the
backlight is on, then check if LVDSVDD has voltage. If no voltage, then it is the
reason that the drive tube of voltage is destroyed. If LVDSVDD is OK, then please
check LVDS cable.
PW106 checks the status of earphone socket. When the earphone is inserted into
the earphone socket, the EAR-INT signal sent to PW106 will be high level. Then ,
PW106 will low down STANDBY signal, which connect the signal of control end of
amplifier chip LX1722. When the STANDBY signal is high level, then amplifier works;
otherwise, the amplifier enters the standby mode.
It should be noted that sometimes if the connector between mini I/O board and IO
board is lax or pulled off, then EAR-INT will be high level and speaker has no
voice output. Therefore, if maintain the TV with no-voice-output speaker, please
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