Roadstar LCD-8412K User manual

Service Manual - LCD-8412K/S
R
LCD-8412K/S
Service Manual - LCD-8412K/S

Repairing precedures for no sound, no picture and no
light.
NO
NO YES
NO YES
YES NO
YES
YES
Check whether power indicator lights in red.
YES
Check whether +5
V
supply of CPU is
normal or not.
Press POWER to check whether
0~5V or 5~0V change is
available on CPU ○,7pin or
not.
Check whether
input +12V and
78L05 is broken or
not.
Check whether
C1815,B1203 for ON/OFF
of CPU and subseq
u
ent supply
circuit is
short-circuited or not.
Check whether
external circuit
for key input pin
and CPUP10)P11)
pins are normal or
not.
Check whether each voltage for the
output of power supply is normal or not.
Change 32K cillation
Change
CPU
Change B1203 C1815.
R
epair power supply and
supply circuits.
Check whether
output of high
voltage is
available or
not.
Check whether high
voltage supply N25 is
open-circuited or nt.
Change audion of
high voltage
circuit or the high
voltage
transformer.
Change LCD screen Check why N25 is open-circuited.
YES
YES
YES
NO
YES
NO NO
NO
YES
NO

Repairing procedures for Inferior color
NO
NO
NO
NO
Check whether output voltage fro
m
LA76810○,19○,20○,21 is normal or not.
Whether LA76810 ○,30 ○,31 pins
are short-circuited or not
and whether ○,18pin is normal
or not.
Check whether loop of IR3Y26
○,8○,9and LA76810○,19○,20○,21
is normal or not.
Change the broken elements of loop.
Change module of
LCD software.
Check
w
hether
periphery of
IR3Y26 is normal
or not.
Change IR3Y26
YES
YES

- 3 -
WITH Sound, with light and black screen
YES
NO
Check whether power suppl
y
of LA76810 ○,25 ○,18 pins is
normal or not.
Check whether LA76810○,13○,12
○,11pins are normal or not.
Check power supply.
Check whether line
field pulse of CPU
is normal or not.
W
hether the ground
resistance of LA76810 ○,29
pin is normal or not.
Check the
LA76810line field
synchronous
circuit.
W
hether it is ok
after change CPU.
Check +5V +7.5V power
supply of IR3Y26 is normal
or not.
Change the resistance.
Check if the copper sheet of
line field synchronous pulse
loop is open or
short-circuited or not.
Check LCD screen and replace.
Change IR3Y26.
YES
NO
NO
YES
YES
NO
NO
NO YES

- 4 -
Repairing Procedures for line field synchronization
NO
YES
NO
YES
YES
YES
NO
Check whether +5V +8Vpoweer
supply of LA76810 is normal or
not.
Repair power supply.
Check whether peripheral circuit
of LA76810 pin is normal or not.
Change 1u 333 capacitance
Check peripheral circuit of 4001
IC Pcircuit for treatment of
line field synchronization).
Check the connector pin to LCD screen is normal
or not..
Change module.
Check the abnormal part.
Change LCD screen.
NO

,repairing procedures for white light.
NO
YES
NO
NO
YES
NO
NO
YES
Test whether the switch power supply +5V +8V an
d
–
15V are normal or not.
W
hether repair power suppl
y
and subsequent circuit is
short-circuited or
overloaded.
Test whether IR3Y26+5V and +7.5
p
ower su
pp
l
y
is normal or not.
Check the loop o
f
p
ower supply.
Change LCD screen.
Check the loop of
power supply circuit.
Test whether +5V, +17V and –15V of
bus socket is normal or not.
Change module of LCD screen.
Check whether
I
R3Y26 is broken
or not.

NO SIGNAL.
YES
NO
YES
NO
YES
NO
YES
Test whether +40V is normal or not.
Check 40V loop.
Test whether wave band switch voltage is available
with CPU ○,1○,41○,42 pin. Test pin VT output voltage
is normal or not.
Check whether AGC voltage for +5V power supply of T
V
tuner is normal or not. Check the TV turner VT voltage
is normal or not.
Change CPU.
Change the TV tuner.
Check whether circuit of pre-central
amplifier and periphery of LA76810○,50
pin is normal or not.
Check periphery of ○,50pin for
pre-central amplifier.
Check 5V power suppl
y
and AGC circuit, and
also check the circuit
of VT voltage.
NO

Can not store program.
NO
NO
YES
Check whether 32V-tuning
voltage is normal or not.
Repair tuning loop.
Check whether AFT circuit is normal or not.
Change TV tuner and sound surface
Repair AFT circuit.
YES

- 8 -
With picture, no or low sound and distortion
YES
NO
YES
NO
T
est whether loudspeaker is open
circuited or not.
Test whether power amplifier
386 is broken or not.
Change loudspeaker.
Check whether LA76810○,1○,2pins are normal or not.
T
est whether power
amplifier 386 is
broken or not.
Change peripheral
elements or ○,1○,2
pins.
Check whether
LA76810 ○,52 ○,53 ○,54 pins
are normal or not.
Change peripheral circuit of ○,52○,53○,54.
Change
LA76810.
YES
NO YES
NO

Dark light
NO
NO
YES
NO
YES
Check whether contrast
and bright are adjusted
to minimum or not.
Check whether power
supply of each circuit
is normal or not.
Check supply power
circuit.
A
djust potentiometer of
m
ain board BRI to see
whether there is change or
not.
Check whether
p
eri
p
heral elements of IR3Y26 are normal or not.
Adjust till OK
Change IR3Y26
Set analog quantit
y
of TV at standard.
YES

with picture, with sound, no character or inferior
color.
NO
NO
Check CPU 32K crystal oscillation.
Check whether pulse input of
CPU line field
synchronization is normal or
not.
Change 32K
crystal
oscillation.
Check whether CPU ○,22 ○,25 to
LA76810 ○,13 ○,16 is normal or
not.
Check line field
synchronization
circuit.
Inferior
character
color.
Change CPU or LA76810.
Change loop elements.
NO
YES
YES
NO

AV no picture or no sound.
NO
NO
YES
Check whether A
V
connects wire is
normal or not.
Check input socket.
Change AV connect wire
Check the loop of audio and LA76810○,51pin, and
the loop of video and LA76810○,42 pin.
Change input socket.
Change LA76810
YES
YES

No flip vertical/horizontal function
NO
YES
Press keys on remote control.
Test CPU ○,35○,36 pins to check 1
W
hether
05V or 50V change is available on
P15)P16) pinR 2Whether 05V or
50V change is available on ○,3○,4pins
for picture mode selection.
Check whether CPU○,35○,36○,3○,4to
the copper sheet of LCD module
○,3○,4○,18 ○,19 pins is open
circuited or not.
Change remote
controller and try
again.
Change remote
controller
head.
Chan
g
e LCD screen.
NO

1 2 3 4 5 6
A
B
C
D
6
54321
D
C
B
A
11 22
3
34 4
5
5
CF1
CF38.0
FOF 1
KIF 2
4.43F 3
IDF 4
4.0F 5
R-Y 6
B-Y 7
GND 8 4.0
9
SAND
10
4.43
11
SYS
12
KIL
13
VI
14
VCC(8V)
15
EOU
16
IC10
LA7642N
AUDIO
1
FM.OUT
2
PIF.AGC
3
RF.AGC
4
IF.IN
5
IF.IN
6
IF.GND
7
IF.VCC(5V)
8
FM.FILTER
9
AFT.OUT
10
BUS
11
BUS(L)
12
ABL
13
R.IN
14
G.IN
15
B.IN
16
BLANK.IN
17
RGB.VCC(8V)
18
R.OUT
19
G.OUT
20
B.OUT
21
ID
22
VER.OUT
23
V.RAMP.ALC
24
H/BUS.VCC
25
AFC.FILTER
26
HOR.OUT
27 FBP.IN 28
REF 29
CLK.OUT 30
I HHDL.VCC 31
CCD.FIL.TER 32
I HDL.GND 33
SECAM.IN 34
SECAM.IN 35
C AFC.FIL.TER 36
SEL.VIDED.OUT 37
X.TAL 38
C AFC.FIL.TER 39
SEL.VIDEO.OUT 40
V C DEF.GND 41
EXT.V.IN/Y.IN 42
V C DEF.VCC(5V) 43
INT.V.IN/C.IN 44
BLACK.STRECH 45
VIDEO.OUT 46
VCO.FILER 47
VCO 48
VCO 49
PIF.APC 50
EXT.AUDIO.IN 51
SIF.OUT 52
SND.APC 53
SIF.IN 54
IC7
LA76810
1
2
3
4 5
6
7
8
IC9
CSC386P
+5V
R41
10K
R42
6K8
C33
473
C35
223
C37
223
C39
103
GND
C41
103
R47
100K
R48
100K R5027K
C42
1uF
+5V
SD
SCL
SDA
AFT
C45
1uF
R51
100K
GND
R65
2K2
R67
120 R68
3K3
R72
2K2
C47
474
C46
224
C48
333
+5V
GND
C49
1uF
C50
100uF
AGC
C85
39P
C86
102
C87
1uF
C88
18P
R86
1K
R87
330
L7
15uH
GND
C89
10uF
C96
10uF
C93
0.47uF
C90
0.47uF
R88
180K
R89
330
C92
470P
C91
56P
LT1
R92
1K5
R90
1K
R97
22K
R91
560K
R94
20K
C95
1uF
C94
4u7
C97
0.47uF
GND
C99
103
C98
220P
R95
150
R96
1K
R93
2M
C100
18P X2
4.433MHz
C103
10uF
C102
103
R98
1K
R99
10K
R100
150
C129
103
C130
103
C133
103
Q11
A1015
C104
103
+5V
C101
103
C106
103
C105
10uF
C107
10uF
R102
100
R25
10K
R104
1K
R136
4K7
R103
1K
R105
4K8
GND
R101
1K
C132
1uF
C135
1uF
C136
1uF
C137
1uF
C131
1uF
C134
1uF
+8V
C119
2u2
C121
470uF
C123
100uF
C84
472
R32
3K3
R120
22
R35
10
R31
3K3
GND
1
2
J7
+ -
C108
47P
C51
472
VOL
RO
GO
BO
VER
HOR
SLIRROUND
1
50/60
2
ALAMP(16:9)
3
WO.OF-VOL(4:3)
4
VOLUME-L
5
VOLUME-R
6
POWER
7
VT
8
GND
9
XTAL1
10
XTAL2
11
VDD(5V)
12
KEY
13
AFT
14
SIF2
15
SIF1
16
RESET
17
FILT
18
CHRDMA
19
V.SYNC
20
Y.SYNC
21 R.OUT 22
G.OUT 23
B.OUT 24
BLANK 25
IO 26
SDAO 27
SCLO 28
SDAO1 29
SCL1 30
SAFTY 31
S-VHS 32
SD 33
IR 34
U/D 35
L/R 36
MUTE 37
AV1 38
AV2 39
ENGLISH 40
BAND2 41
BAND1 42
IC1
LC863324A
A0 1
A1 2
A2 3
A3 4 SDA
5
SCL
6
TEST
7
(5V)
8
IC5
24C04
AGC VT BU BH BL BM IF ANT
TU1
TDQ-3CV1
C38
103
C34
104
C30
100uF
C1
22uF
C3
10uF
C31
10uF
C32
10uF
R40
150
R39
100
R43
4K7
R44
220
R45
1K
R46
33
ANT1
C2
104
C5
104
C6
104
R4
22K
R6
22K
R7
22K
R3
12K
R2
51K
R5
22K
R10
470
R8
4K7 R9
10K
R15
1K2
C4
680P
C7
100P
R11
10K R12
10K
R13
10K
R14
10K
R16
680
R17
10K
R26
10K
R21
330
R23
270K
R69
4K7
R20
4K7
R22
8K2
R24
1K5
C36
104
+33V
C40
103
+8V
R49
22K
R52
100
R53
22K
R54
22K
R56
22K
R55
100
R57
22K R58
100
R59
22K
R61
22K
R60
220
R62
22K
R63
220
R66
3K3
R70
4K7
R64
3K3
R71
4K7
X1
32K
C8
18P
C9
15P
1 2 3 4
J1
IR C5V KEY GND
C10
103
C13
1uF
C14
22uF
Q2
A1015
ZD1
3V9
C12
103
C5V
C5V
C5V
C5V
C5V
C5V
AGC
REMOTE
Q1
C1815
Q9
C388A
R1
1K
C43
104
HS VS
+8V
+8V
+5V
BI
GI
GI
BI
RI
RI
SDA
SCL
SD
+5V
REMOTE
AFT
+12V
VOL
+5V
+8V
POWER
R34
1K
R33
24K
+5V
FBP
BLANK
BLANK
1 2 3 4 5 6 7 8 9
10 11 12
13
14
15
16
17
18
19
20
21
22
23
24
25 26 27 28 29 30 31 32 33 34 35 36
37
38
39
40
41
42
43
44
45
46
47
48
IC13
IR3Y26A
C147
104
R157
100
R158
100
R159
100
R154
51K
R160
62K
R156
47K
R155
33K
C148
104
C149
104
C158
104
C159
104
C160
104
C161
104
R184
12K
C157
220uF
C151
104
C152
104
C150
104
R167
1K5
R165
1K5
R166
1K8
R117
47K
R116
47K
R119
36K
R118
47K
R123
24K
R121
47K
R122
47K
R134
1K
R126
36K
R124
56K
R125
47K
R128
36K
R127
47K
C117
104
C118
104
C120
104
C122
104
C125
104
C126
104
R133
100
R135
100
R130
36K
R129
47K
R132
51K
R131
30K
C127
104
C128
104
R162
10K R163
10K
R164
10K
BRG
VR2
5K
VB VG VR
RO
GO
BO
SYNC
FRP
PSI
+7V
5V
5V
5V
R108
10K
R107
10K
R106
18K
R142
2K2
R110
10K
R113
10K
R109
10K
R151
10K
R111
33K
C114
102
+8V
+5V
+5V
C140
102
C141
104
R143
4K7
C143
104
C144
103 C146
103
C115
103
C145
103
Q12
C1815
R112
3K9
R152
3K3 R153
3K3
R150
8K2
R149
10K
Q17
C1815
Q14
C1815
R144
22K
R145
4K7
VS
VER
HS
SYNC
HOR
FBP
1
2
3
4
5 6
7
8
9
10
T1
TRANS-09
C22
104
C15
104
C16
104
C17
104
C18
104
C21
104
Vin 1
GND
2
Vout
3
IC2
78L05
C23
470uF
C19
100uF R30
47
R27
10K
R28
1K
Q4
B1202
1 2 3 4 5
6 7 8
IC6
2368
C66
104
C74
104
C58
102
R77
330K R78
27K
R82
6K8
R80
2K2
R81
82K
R29
180K
R75
100
R83
22K
R84
2K2
VR1
1K
C20
10uF
C56
100uF
C24
470uF
L1
D8
IN5819
D3
IN4937
D6
IN4937
D4
IN5819
D5
IN4937
D7
IN5819
C53
100uF
L4
100uH
L5
100uH
L6
100uH
C54
104 C55
104
C52
104
C60
104
C111
104 C112
104
C113
104
C63
104
C67
104
C68
104
C69
104
C70
104
C71
104
C75
104
C76
104
C77
104
C79
104
C62
220uF
C59
220uF C61
220uF
C65
47uF/25V
C64
100uF
C78
100uF
C73
220uF
C72
220uF
C57
22uF/50V
C110
22uF/50V
C109
22uF/50V
R74
10K
R73
2K7
ZD3
17V
ZD2
33V
C5V
Q3
C1815
Q10
3518
POWER
C27
104
C28
104
C80
104
C25
470uF
C83
27P/3KV
C29
1uF
+33V
+17V
+8V
+7V
-15V
5V
+5V
+12V
R79
10K
R76
22K
P/N
16:9
4:3
R139
1K
R174
1K
+5V
R140
***
R138
100
C138
1uF
R141
75
D9
IN5819
C124
104
1 2 3 4 5 6
GND 7
8 9
10 11 12 13
VCC
14
IC8
4001
1 2 3 4 5 6
GND 7
8 9
10 11 12 13
VCC
14
IC12
4001
Q13
C1815
+8V
1
2
3
4
5
6 7
8
ST1
U15
1
2
3
45
6
7
8
IC3
T5001
1
2
3
45
6
7
8
IC4
S140
L2
100uH
FU1
N25
Q6
C1815
Q8
A1015
C26
10uF
L3
39uH
D1
S41G
R36
1K
R85
2K2
R37
1K
R38
1K3
Q5
DKPJ
Q7
DKPJ
D2
M.O
1
2
J6
FU3
U185
GND
+17V
5V
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
CON401
30PIN
-15V
PSI
FRP
5V
U/D
L/R
VR
VG
VB
SYNC
GND
GND
GND
GND
C44
103
+5V
16:9
4:3
C178
102
R230
12K
R231
10K
U/D
R207
1K3
JV-845LA
P/N
DK1
DC1
ANT2
AV1
AV2
PY3
PY4
PY2
L/R
PY1
U/D
L/R
U/D
L/R
FUK1
+12V
IVIY
IVIY
CSY
PY7
AUDIO
C11
***
R18
0R
R19
5K6
PY5
CSY
R114
47
C81
102
PY6
R115
4K7
R146
1K5
SK1
POWER
SK7
CH+
C82
104
R148
3K9
VCC 3
GND 2
IR 1
IC11
REMOTE
LED1
R137
150K
SK2
TV/AV
SK6
CH-
SK3
MENUV
SK5
VOL+
R161
4K7
R147
2K7
R169
27K
R168
8K2
1 2 3 4
Y1
IR C5V KEY GND
SK4
VOL-
ANT3
PT33 SYNC
PT32 IVIY
PT14 L/R
PT30 U/D
PT36CSY
PT40PSI
PT31 FRP
PT37 VB
PT38 VG
PT39VR
PT35 4:3
PT34 16:9
PT13 P/N
PT6
PT7
PT5
PT12
PT2
PT1
APC
PT3
AUDIO
PT4
VIDEO
PT8
PT9
PT16
PT15
PT17
PT18
PT19
PT20
PT21
PT26
+33V
PT27
+17V
PT29
+8V
PT28
+7V
PT25
-15V
PT43
+5V
PT24
5V
PT22
12ViN
PT23
C5V
PT10 PT11
PT42
PT41