CV338H-U42-10 maintainance guide презентация

SYSTEM BLOCK

In stand-by condition,
Is the testing point TP14 5V?
Normal booting
Check the Q2, U2, U7, UD1 related devices respectively.
After power on, check the following testing point:
Is the testing point TP7 5V?
& Is the testing point TP11 0.98V ?
& Is the testing point TP4 1.12V?
& Is the testing point TP9 3.3V?
Picture 1: Power Units Problem Solving
(Mainboard can not boot)
Y
N
OK
Check the U3, U13 related devices
N
Y
Y
N
Check the U1
DC-DC Converter circuit
Is the main board testing point TP10 1.5V?
& Is the testing point TP12 3.3V?

Black screen
Is the testing point TP8 12V?
Is the alignment of LVDS cable correct?
Does the LVDS socket welded correctly?
Are the LVDS signals normal?
Are the lines from CPU to LVDS intact?
Is the status of switching MOSFET
Q4 on?
Is the control signal PANEL_ON/OFF
high?
Check the 12V supply voltage, being
short-circuited?
N
N
Y
Y
Does the main chip welded
correctly?
Is the screen OK?
Inverter is broken or
connecting line is not good.
Picture 2
Display unit ( black screen)
The main chip(CPU)
is damaged.
N

No sound
Is there any audio signal input?
or is amplifier power supply normal?
Check peripheral
audio equipment
and amplifier power
supply circuit
Is there any input signal from U12 to the
pin 3 and 12 of UA1（RDA3118e)?
N
Y
Y
N
Is the volume MUTE
setting normal?
Resetting
Is there any output
signal from JA1?
Y
N
Check external
Loud speaker.
Check if the UA1 welded
well, re-weld UA1 or change
RDA3118e chip.
N
Y
Check and repair network of
the connecting part between
U12 and UA1
Picture 3
Audio part (no sound)

TV no searching
/no image
Picture 4
T2+T+C Function unit (ATV/DTV video broke down)
Is the external RF input
signal normal?
N
Check and repair peripheral
RF Equipment.
Y
Does the bead FBT4 output 3.3V?
Check and repair U8 network
Y
N
Check R99 and R101,
Is there I2C data?
Check and repair I2C network
N
Y
Check Tuner has signal output?
N
Y
Repair UT1 to U12 middle-Frequency part net,
Check the tuner UT1
related circuits

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

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