Roadstar lcd 8412 schematic

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- LCD-8412K/S

- LCD-8412K/S

LCD-8412K/S

Service Manual

Service Manual

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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.

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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 -