Sharp LL-T181A (serv.man15) Service Manual ▷ View online
CHAPTER 4. TROUBLESHOOTING
No power supply
LED comes on in green when
power switch is turned on?
power switch is turned on?
No
Yes
LED comes on in red.
LED comes on in orange
Replace any defective component parts
(main PWB, SW PWB, cables)
(main PWB, SW PWB, cables)
Check whether sync. signal is output from
D-sub board.
D-sub board.
Replace D-sub board.
Check that:
• LED is broken.
• CN7 (1st pin) to IC34 (52nd pin) for proper
routing
• Cables for disconnection
• LED is broken.
• CN7 (1st pin) to IC34 (52nd pin) for proper
routing
• Cables for disconnection
Check whether:
• The monitor is not in power save mode
(no sync. signal input).
1 The computer is not turned OFF.
2 The RGB cable is disconnected.
3 The sync. signal is output from the RGB
cable.
• The monitor is not in power save mode
(no sync. signal input).
1 The computer is not turned OFF.
2 The RGB cable is disconnected.
3 The sync. signal is output from the RGB
cable.
Yes
Yes
No
No
No
Yes
No
Check power input system.
1 AC adapter
• Normal?
• Connected properly?
2 Fuse (DC jack PWB)
• Blown
3 Microprocessor (IC34)
• +5V (MVCC) ?
4 LED
• LED is broken?
• CN7 (1st pin) -> IC34 (52nd pin)
• CN7 (2nd pin) -> IC34 (51st pin)
• Cable is disconnected?
1 AC adapter
• Normal?
• Connected properly?
2 Fuse (DC jack PWB)
• Blown
3 Microprocessor (IC34)
• +5V (MVCC) ?
4 LED
• LED is broken?
• CN7 (1st pin) -> IC34 (52nd pin)
• CN7 (2nd pin) -> IC34 (51st pin)
• Cable is disconnected?
1
Replace any defective unit:
( 1 AC adapter, 2 DC jack PWB,
3 main PWB, 4 switch PWB)
( 1 AC adapter, 2 DC jack PWB,
3 main PWB, 4 switch PWB)
Does backlight come on?
No
Yes
Check D-sub PWB.
Normal
Abnormal
Replace D-sub PWB.
Replace inverter PWB unit.
Replace LCD module.
• Check inverter PWB unit.
Note: Pay attention to a high voltage when
checking output side (1800 Vrms at starting).
Note: Pay attention to a high voltage when
checking output side (1800 Vrms at starting).
Check CN1 (CN2) pin terminals.
Pin No. Name Check voltage
1 VIN +12V
2 GND 0V
3 BRT1 (BRT2) 0V
4 ALM1 (ALM2) +5V
5 ON/OFF +5V
Pin No. Name Check voltage
1 VIN +12V
2 GND 0V
3 BRT1 (BRT2) 0V
4 ALM1 (ALM2) +5V
5 ON/OFF +5V
1
2
Abnormal
Normal
Abnormal
Normal
Check output circuit to CN1 (CN2).
1 When VIN is NG:
(1) Main PWB F1, F2 defective, or
(2) DC jack PWB F1 defective
2 When BRT is NG
Operation PWB defective
3 When ON/OFF is NG
(1) DC jack PWB F1 defective, or
(2) Main PWB D3 defective
1 When VIN is NG:
(1) Main PWB F1, F2 defective, or
(2) DC jack PWB F1 defective
2 When BRT is NG
Operation PWB defective
3 When ON/OFF is NG
(1) DC jack PWB F1 defective, or
(2) Main PWB D3 defective
Replace any defective unit.
(1) of 1 , (2) of 3 : Replace main PWB.
2 : Replace switch PWB.
(2) of 1 , (1) of 3 : Replace DC jack PWB.
(1) of 1 , (2) of 3 : Replace main PWB.
2 : Replace switch PWB.
(2) of 1 , (1) of 3 : Replace DC jack PWB.
Abnormal screen
Check D-sub PWB.
Abnormal
Normal
Change the display mode and check the
screen condition.
screen condition.
Replace D-sub.
Screen remains
black.
black.
Screen remains
white
white
Screen jittering or characters
on screen flickering
on screen flickering
Abnormal color
Are PHASE, CLOCK
adjustable?
adjustable?
Yes
No
Set H-POS and V-POS so that an abnormal
area appears at the gradation part of the
pattern.
Does the abnormal area move when BRIGTH
or CONT is changed?
area appears at the gradation part of the
pattern.
Does the abnormal area move when BRIGTH
or CONT is changed?
Switch PWB defective
Main PWB defective
Replace LCD module.
2
Reset the microprocessor and check to see if the screen condition changes.
(Turn the power on, holding MENU and SELET buttons down.)
(Turn the power on, holding MENU and SELET buttons down.)
OSD adjustment PHASE,
CLOCK are normal?
(If not, adjust referring to
Instruction manual.)
CLOCK are normal?
(If not, adjust referring to
Instruction manual.)
Display the adjustment pattern
on the screen using the
adjustment FD.
Perform AUTO GAIN
CONTROL.
on the screen using the
adjustment FD.
Perform AUTO GAIN
CONTROL.
Check the following signals:
1 +12V power supply for LCD
(C91 +terminal)
2 +5V power supply for LCD
3 Clock signal
4 DE signal
For 2 3 4 , see a separate
drawing.
1 +12V power supply for LCD
(C91 +terminal)
2 +5V power supply for LCD
3 Clock signal
4 DE signal
For 2 3 4 , see a separate
drawing.
Yes
Yes
No
No
CHAPTER 5. TRIMMING LEAD WIRES
Trimming inside wiring cables
1. Lamp cable
Trim the lamp cable as shown in
in the sketch below. (Press
against the plate.)
2. Inverter cable
Use caution not to get the cable caught when installing the cover
plate. (
plate. (
)
3. Switch cables
(1) Use caution not to get the cables caught when installing the
cover plate. (
)
(2) Place the protection tube at the corner, using caution so as not
to allow the cable to slack. (
)
(3) Secure the band in the direction shown in
and do not allow
the cables to slack to prevent the cables from getting caught
when installing the rear cabinet
when installing the rear cabinet
(4) Put the slack of the cables into the hole
.
Note: In
and
, do not pull the cables too strong during trimming;
otherwise they might be disconnected from the connector.
3
4
2
clock signal
DE signal
+5V power supply for LCD
1
2
1
6
5
4
3
Cover plate
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