CV338H-T42. Common problems solution

1.

CV338H-T42
Common problems solution
—Power Unit Problem Solving
—Display Unit Problem Solving
—Audio Unit Problem Solving
—Functional Unit Problem Solving

2.

3.

Picture 1: Power Units Problem Solving
(Mainboard can not boot)
In stand-by condition,
Check TP1,
Whether got 12V
N
Y
Whether main board testing point TP14 got 5V?
testing TP12 got 3.3v?
N
Check AC power
supply circuit
Y
Normal booting
Check the U10, U15
related devices
After power on, check
whether testing point TP9
got 3.3v testing point TP10
got 1.5v,testing TP4 got
1.1v?
N
Whether power chip
DCDC(U10,U11,U7) works?
Y
OK

4.

Picture 2
Display unit ( black screen)
Black screen
Whether the voltage that
power panel supply to Inverter
is normal?
Y
N
Check the socket that controls Inverter,
whether the voltage output from pin 34 of JL1
is in high level?
N
Check and repair the
network that controls
Inverter ON/OFF
Y
Inverter is broken or
connecting line is not good
Check the external power supply circuit

5.

No sound
Picture 3
If there is any audio signal input
or Whether amplifier power supply
is normal?
N
Audio part (no sound)
Y
Whether the volume,
MUTE
setting is normal?
N
Y
Whether there is
signal output from JA1?
N
Y
Whether there is signal
input in
UA1 MP7752 pin 1/28?
Y
Check
peripheral
audio
equipment:
amplifier
power
supply
circuit
Check
Resetting
external
loudspeaker
Check if the U12 welded
Well , re-weld UA1 or change
MP7752 chip.
N
Check and repair
network
of the connecting
part between
U12 and UA1

6.

TV no searching
/no image
Picture 4
T2+T+C Function unit (ATV/DTV video
broke down)
Check whether
external RF input signal
is normal?
N
Y
Whether main board testing FBT4 output 3.3V?
Y
N
Check R99,R101,
whether there is I2C data?
N
Y
Check Tuner have single output?
Y
Repair U112 to
U12 middleFrequency part
net
Check and
repair
peripheral
RF
equipment
N
Check the
tuner U112
related circuits
Check and repair
I2C network
Check and
repair U10
network

7.

Picture 5
TV no sound, only picture
Function unit (ATV/DTV no
sound)
Whether there is
sound under PC AV
N
Y
Whether software is
OK? input system is
set correctly?
Y
Refer to “NO SOUND”
repair guide
Change U12

8.

Picture 6
Function unit PC
Under PC
Whether the
contact of
VGA socket
is good?
Miss color,
Color
cast
Image not
in the middle
Whether U12
R.G.B input signal is normal?
Y
Carry out
auto-adjust
operation
The system
setting
is incorrect,
reset it
N
Image
shakes
Whether VS,HS signal
is regular or stable?
Y
Check VGA
input circuit
No signal
OSD setting
doesn’t match,
reset it,
or input mode
doesn’t support
N
Check VS.HS
circuit
Whether the
contact of
VGA socket
is good?
Check VS.HS
circuit

9.

Picture 7
Function unit HDMI
Under HDMI
There is image
but no sound
Whether HDMI
contact
is good?
No image
Check whether
HOTPLUG pin is
high?
Whether there is
sound under PC?
Y
Check HDMI related
network of U12
Y
Change the software and
Re-weld the U12&HDMI
connecter
Y
N
Check HDMI
input network
and EDID
Refer to "no
sound" repair
guide
N
Check HDMI
and input
network