Sharp LL-191A Service Manual ▷ View online
LL-191A-W/B
HARDWARE DESCRIPTION
5 – 1
CHAPTER 5. HARDWARE DESCRIPTION
[CIRCUIT DESCRIPTIONS]
1.
MAIN PWB UNIT
1-1. Scaler U10 (MST9111A)
The MST9111A converts an image input into the specified display size up tot S x GA size and outputs data to the LCD display as LVDS data stream.
The MST9111A holds one line of analog input and processes analog input signals from D_Sub (J6).
Additionally, it has the OSD (On-Screen Display) function.
1-2. MCU U6 (MTV312M64)
The MTV412_PLCC is an 8-bit
z
controller having 4 x 8 bit general-use I/O port, including 64K byte Flash EEPROM (for program) and 256+1 Kbytes
RAM (for data).
It controls the scaler, the audio amplifier, and the backlight inverter according to the serial EEPROM (U2) information.
1-3. Audio amplifier U12 (AP2121)
The AP2121 is a stereo power amplifier of 2W + 2W, and is driven by the power voltage of 5V to drive two speakers (L and R) of 8
Ω
. The max.
speaker output is 1W + 1W. The output is also connected to the headphone pin. When a head phone plug is inserted, the speaker is disconnected
and sound is provided to the head phone.
and sound is provided to the head phone.
It is also provided with the volume adjustment function and the standby function.
2.
POWER SOURCE/INVERTER PWB UNIT (3190-0032-0191)
2-1. Power source section
The power circuit operates on AC90 - 264V (50/60Hz), and provides two lines of outputs: DC5V (max. 1.2A) and (max. 2.6A). DC12V is also used in
the inverter section in the unit.
A protection circuit against overvoltage, overcurrent, and high temperature. Two fuses are provided on the primary side.
A protection circuit against overvoltage, overcurrent, and high temperature. Two fuses are provided on the primary side.
2-2. Inverter section
The inverter section is the lighting circuit of the 4-lamp backlight (fluorescent tubes) to adjust brightness of the LCD panel, and is operated on DC12V
generated in power source section of the unit. When a trouble occurs in the lamp, the protection circuit may stop the operation of the inverter unit.
generated in power source section of the unit. When a trouble occurs in the lamp, the protection circuit may stop the operation of the inverter unit.
The inverter unit provides a high voltage of about 1000V to the lamp by the boosting transformer.
When repairing, use an extreme care not to bring your hand near the output connecter during conduction. Note that it is extremely dangerous.
LL-191A-W/B
TROUBLESHOOTING
6 – 1
CHAPTER 6. TROUBLESHOOTING
■
NO POWER SUPPLY
* Inverter cable is separated?
* Inverter cable is disconnection?
* Check the output of each pin
2 pin (ON/OFF) 4pin (DIM)
* Inverter cable is disconnection?
* Check the output of each pin
2 pin (ON/OFF) 4pin (DIM)
No power supply
Does LED turns on in green
when power switch is turned
on?
when power switch is turned
on?
No
No
No
No
No
Yes
Yes
Yes
Yes
Yes
No output +5V from
Power supply/Inverter Unit.
Power supply/Inverter Unit.
Yes
1) PC is turned off?
2) RGB cable is disconnected?
3) Synchronizing signal is output from RGB
2) RGB cable is disconnected?
3) Synchronizing signal is output from RGB
cable?
Check whether the unit is in power save
mode (synchronizing signal is not input.).
mode (synchronizing signal is not input.).
Synchronizing signal is input to main PWB?
Replace RGB cable
with a new one.
with a new one.
LED turns on in orange?
Check power input system.
Replace any defective unit.
[ 1) Power supply/Inverter Unit,
2) Main PWB, 3) Switch PWB,
4) Audio PWB] with a new one.
[ 1) Power supply/Inverter Unit,
2) Main PWB, 3) Switch PWB,
4) Audio PWB] with a new one.
Backlight turns ON?
Check for RGB cable input
signal.
signal.
Replace RGB cable.
Normal
Normal
Normal
Defective
Defective
* Check inverter PWB unit.
Note: Use caution when checking output
Note: Use caution when checking output
side because it has a high voltage.
Replace LCD module lamp with
a new one.
a new one.
Replace Power supply/
Inverter Unit. With a new one.
Inverter Unit. With a new one.
A
1) Power supply/Inverter Unit Normal?
Connected with the MAIN PWB properly?
2) Blown out fuse (D201)?
Check VCC5V+, VCC2.5V and VCC3.3V
are output?
3) Check POWER switch and LED for
breakage.
Connected with the MAIN PWB properly?
2) Blown out fuse (D201)?
Check VCC5V+, VCC2.5V and VCC3.3V
are output?
3) Check POWER switch and LED for
breakage.
Replace Power supply/Inverter Unit.
LL-191A-W/B
TROUBLESHOOTING
6 – 2
Set volume to max and has the output
waveform appeared in 4, 9, 16, 21 of
U12 pin?
waveform appeared in 4, 9, 16, 21 of
U12 pin?
Is connection of from a main PWB cable
to key PWB and a speaker cable normal?
to key PWB and a speaker cable normal?
No
Speaker defective.
Yes
No
No
No
Yes
Yes
■
NO SOUND
■
Screen does not operate normally.
A
Screen does not operate normally.
Check RGB cable.
Defective
Replace RGB cable with
a new one.
a new one.
Check screen condition by changing display modes.
Operate the "ALL RESET" to check if screen condition changes.
(Press and hold MENU and SELECT buttons while turning on power switch.)
(Press and hold MENU and SELECT buttons while turning on power switch.)
Screen stays in black.
Screen stays in white.
Screen jitters or on-screen
characters flicker.
characters flicker.
Abnormal color
Check the following signals
1) Check if module control signal is output (U10).
2) Check if VLCD voltage is output normally.
Yes
No
Yes
No
Yes
No
CLOCK and PHASE
can be adjusted?
can be adjusted?
Does abnormal area move on
screen when BLACK LEVEL or
CONT is changed after H-POS
or V-POS is set?
screen when BLACK LEVEL or
CONT is changed after H-POS
or V-POS is set?
Switch PWB defective
Main PWB defective.
LCD panel defective.
No sound
Audio cable defective.
Yes
No
U12 defect and so
Audio PWB defective.
Audio PWB defective.
Yes
Normal
Defective
Is the 7, 18, 19 pin of U12 about 5V?
Power supply inverter
PWB defective.
PWB defective.
Check
3, 22pin of U12 signal
3, 22pin of U12 signal
Has the input waveform
appeared in 5, 23 pin of U12 ?
appeared in 5, 23 pin of U12 ?
U601 of Main PWB defect and so
Main PWB defective.
Main PWB defective.
Is the signal outputted normally
from the source of an Audio signal?
from the source of an Audio signal?
LL-191A-W/B
CIRCUIT DIAGRAM & PWB LAYOUT
6 – 1
A
B
C
D
876
5
4
3
21
1
2
3
4
5
6
7
8
D
C
B
A
A
B
C
D
876
5
4
3
21
1
2
3
4
5
6
7
8
D
C
B
A
A
B
C
D
876
5
4
3
21
1
2
3
4
5
6
7
8
D
C
B
A
A
B
C
D
876
5
4
3
21
1
2
3
4
5
6
7
8
D
C
B
A
1/6
D-SUB
+5VX
DDC_POWER
DDC_POWER
DDC_POWER
+5VX
+3.3VX
RIN
5
GIN
5
BIN
5
SOG
5
GNDR
5
GNDG
5
GNDB
5
HSYNC
4,5
VSYNC
4,5
DDC_CLK
4
DDC_DAT
4
ALL RESISTORS 1/10 WATT,5% UNLESS NOTED.
ALL CAPACITOR VALUES IN uF UNLESS NOTED.
ALL RESISTORS VALUES IN OHMS UNLESS NOTED.
NOTE : NC MEANS "NOT CONNECTED ON PCB BOARD"
ALL CAPACITORS 50 VOLT & 105"C UNLESS NOTED.
ALL RESISTORS 25 VOLT IN .1uF UNLESS NOTED.
M= METAL 1%
C97 22P
C11
.047u
R12
100
R7 75
D8 BAV99
1
3
2
R19
NC
R5
BEAD30
R26
22
R17
75
D3 BAV99
1
3
2
C7 NC
D4 BAW70
3
1
2
R14
M600
U1B
74LCX14
3
4
D1 BAV99
1
3
2
U1E
74LCX14
11
10
R15
NC
C3
.047u
C13
.047u
R13
100
J6
DSUB-15
1 6 2 7 3 8 4 9 5
11
12
13
14
15
10
R16 10K
C15
0.1u
C5 NC
R24 10K
D6 5.6V
U1D
74LCX14
9
8
R1
BEAD30
R6
100
C6 NC
D5 5.6V
C10 N.C
R20
75
C8 N.C
R10 100
R22 22
R21 10K
R9 75
R4
100
C12
.047u
C98 22P
C4
.001u
C16 220P
U1C
74LCX14
5
6
C1
.047u
R23 10K
R8 75
R3
BEAD30
R2
100
C14 22P
U2
24LC21
NC
1
NC
2
NC
3
GND
4
SDA
5
SCL
6
VCLK
7
VCC
8
C2
.047u
D7 BAV99
1
3
2
C34 .1u
R11
100
C9 N.C
R18
M600
D2 BAV99
1
3
2
R25
22
CH
APTER 7.
CIR
CUIT
DIAGRAM
& PWB
LAYOUT
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