Service manual

Symptoms Possible cause Remark
·Check if the power plug has been inserted properly
into the socket.
·Check if the power switch has been turned on.
·Check if the power board could work normally. ·Refer to "Power Board Trouble shooting"
·Check if the wires are OK and connected correctly.
·Check if the TV could receive KEY or IR signal
normally.
·Refer to "KEY/IR signal Trouble shooting"
·Check if the Scaler board could work normally.
·Generally,
1)The voltage of BLKON pin in SCALER board
J704 is above 2.4V.
2)24V voltage is supplied to INVERTER
board.
3)5V/12V voltage supplied to the VLCD pin
in SCALER board JF603
4)wires are OK and connected correctly.
the LCD panel lights could be turned on if
the four conditions above is met.we can see
backlight from LCD panel's back.
·If there's still no picture/sound,it
means the SCALER does not work well,we can
check the U20/U18/U21 in the Scaler board
to see if 1.8V /2.5V/ 3.3V is output
well.Check resistances,which connect with
U9,are soldered well.Check the crystal
oscillater beside U9 with oscillograph.
·Check if the LCD Panel could work normally.
·we can use new SCALER board,LVDS wire to
check it.
No/Bad picture in
all sources
·Check if TV is interfered by something,such as high
voltage transmission line.
·Check the SCALER board,LCD panel and LVDS wire
between them.
Generally,the problems below are caused by
LCD panel.
1)bright/dark line on the screen at all
times
2)bright/dark block on the screen at all
times
No/Bad picture in TV
source
·Search the channel again,if it's still NG,
·Check if the TV signal is OK.Maybe there is
interference outside.
·Check if the TV software matches TV signal
format.There may be some bugs in the software
sometimes,update the software if necessary.
·Check if the wire connection is loose.
·Check the tuner board,IO board and SCALER board.
Generally,if the TV-CVBS and SIF are output
from TUNER board,the TUNER board is ok.then
·Check the TTCL,TSDA,CVBS signal in SCART
board JV101.Check the synchronism circuit
in SCALER board.The circuit output voltage
should be about 5V.
No/Bad picture in
Other sources except
TV
·Check the IO board and SCALER board.
·Check the Card reader board if the USB/SD/CF
source's image is abnormal.
·We need to check HDMI board if no HDMI
signal output.
NO/Bad sound in
all/some sources.
·Check if "mute"function is turned on.
·Check if the sound volume is set to minimum.
·Check if the sound system is set correctly according
to the TV signal.There may be some bugs in the software
sometimes,update the software if necessary.
·Check the IO board,loudspeakers and wires between
them.we also need to check mini IO board if the
correlative source does not work well.
·Check the Card reader board if the USB/SD/CF source's
sound is abnormal.
·Check IO board:include power and mute
circuit(high voltage level means MUTE).
·Check
CXA2069Q,TDA9875,LX1722,NJM4558(operational
amplifier) input and output.If there is no
signal output,check the relevant IC' power
supply,crystal oscillatior,IIC.
·Check the relay.
·We need to check HDMI board if no HDMI
signal output.
11.1.Trouble shooting
No power
No picture,no sound
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