Roadstar lcd 8412 schematic
R
- LCD-8412K/S
- LCD-8412K/S
LCD-8412K/S
Service Manual
Service Manual
V
u
R
Repairing precedures for no sound, no picture and no
light.
Check whether power indicator lights in red.
YES
Press POWER to check whether
0~5V or 5~0V change is
available on CPU ○,7 pin or
not.
NO
Check whether
Check whether +5
supply of CPU is
normal or not.
NO
YES
external circuit
for key input pin
and CPUP10)P11)
pins are normal or
not.
NO
NO YES
Check whether
input +12V and
78L05 is broken or
NO YES
not.
Check whether
C1815,B1203 for ON/OFF
of CPU and subseq
circuit is
short-circuited or not.
NO
ent supply
YES
Change B1203 C1815.
Change 32K cillation
Change
CPU
YES NO
Check whether
output of high
voltage is
available or
not.
Change LCD screen
YES
YES
Check whether each voltage for the
output of power supply is normal or not.
epair power supply and
supply circuits.
NO
NO
YES
Check whether high
voltage supply N25 is
YES
open-circuited or nt.
YES
Check why N25 is open-circuited.
Change audion of
high voltage
circuit or the high
voltage
transformer.
m
w
Repairing procedures for Inferior color
NO
Check whether output voltage fro
LA76810○,19○,20○,21 is normal or not.
YES
Check whether loop of IR3Y26
○,8○,9 and LA76810○,19○,20○,
is normal or not.
21
NO
YES
Change module of
LCD software.
Whether LA76810 ○,30○,31 pins
are short-circuited or not
and whether ○,18pin is normal
or not.
Change the broken elements of loop.
NO
Check
periphery of
IR3Y26 is normal
or not.
hether
NO
Change IR3Y26
y
W
W
WITH Sound, with light and black screen
Check whether power suppl
of LA76810 ○,25○,18pins is
normal or not.
NO
Check power supply.
YES
Check whether LA76810○,13○,
○,11pins are normal or not.
12
Check whether line
NO
field pulse of CPU
is normal or not.
YES
NO
hether the ground
resistance of LA76810 ○,
pin is normal or not.
29
YES
Check the
hether it is ok
after change CPU.
LA76810line field
synchronous
circuit.
NO
YES
Check if the copper sheet of
line field synchronous pulse
loop is open or
short-circuited or not.
Check +5V +7.5V power
supply of IR3Y26 is normal
or not.
NO
YES
Change IR3Y26.
Change the resistance.
NO
Check LCD screen and replace.
- 3 -
Repairing Procedures for line field synchronization
Check whether +5V +8Vpoweer
supply of LA76810 is normal or
not.
NO
Repair power supply.
YES
Check whether peripheral circuit
of LA76810 pin is normal or not.
NO
Change 1u 333 capacitance
YES
Check peripheral circuit of 4001
IC Pcircuit for treatment of
line field synchronization).
YES
Check the connector pin to LCD screen is normal
or not..
NO
Check the abnormal part.
YES
Change module.
NO
Change LCD screen.
- 4 -
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