Sharp LL-T155A (serv.man2) Service Manual ▷ View online
CHAPTER4. TROUBLESHOOTING
1
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.
Is the unit in power save mode (No synchronizing
signal input)
signal input)
Check if personal computer is turned on?
Check if RGB cable is connected.
Check if synchronizing signal is applied.
Check if RGB cable is connected.
Check if synchronizing signal is applied.
Is voltage output to key
switch unit connector
terminal (J4)?
switch unit connector
terminal (J4)?
Key switch unit
defective
defective
+12 V/+5 V output at power
unit connector terminal
CN-JP5) ?
unit connector terminal
CN-JP5) ?
Defective
interface unit
interface unit
100 V AC input to power unit
input connector?
input connector?
Defective
power unit
power unit
Backlight comes on?
+12 V and On signal "H" at
inverter terminal (JP5)?
inverter terminal (JP5)?
Check AC
switch and cord.
switch and cord.
High voltage
*1 output to inverter PWB output
terminal?
*1 output to inverter PWB output
terminal?
Defective inverter unit
Check LCD module lamp.
Note 1: Note that up to about 1.4 kVrms is applied when the inverter is started or in normal operation.
Is LED in key switch unit normal?
(Check for disconnected cable.)
(Check for disconnected cable.)
No
Yes
Yes
No
Yes
No
No
No
Yes
Yes
No
Yes
No
Yes
No
Yes
1
Screen is not normal
Check the screen condition by changing the display modes.
Reset the microprocessor to check to see if the screen condition changes.
Screen stays in black.
Screen stays in white
Jittering screen and
flickering characters
flickering characters
Abnormal color
Is RGB setting in OSD
adjustment appropriate?
adjustment appropriate?
Check the following signals
(LCD signal input terminals):
(LCD signal input terminals):
+5V power check for LCD
Clock signal
DE signal
H sync/ V sync signal
Clock signal
DE signal
H sync/ V sync signal
Check LCD signal input terminal
corresponding to the color
condition on screen.
corresponding to the color
condition on screen.
Normal
Abnormal
Backlight system normal
LED lights in green
Brighten screen condition.
LED lights in green
Brighten screen condition.
Under the above conditions,
check LCD signal input terminal.
check LCD signal input terminal.
Defective interface unit
Defective LCD module
Are OSD adjustment PHASE,
CLOCK settings appropriate?
(If not, adjust according to
Instruction manual.)
CLOCK settings appropriate?
(If not, adjust according to
Instruction manual.)
Normal
Normal
Abnormal
Abnormal
CHAPTER5. TRIMING AND PROCESSING LEAD WIRES
Step 1
Put the CCFT cable and LCD cable into shield plate bushings to
prevent them from getting caught when installing the shield plate.
(Figs. 1 and 2)
Put the CCFT cable at the back of the LCD module to prevent it
from getting caught when installing the LCD module.
from getting caught when installing the LCD module.
Step 2
Use caution to prevent the power supply cable and switch cable
from getting caught when installing arm rear cover (Fig. 3).
Use caution to prevent the power supply and switch cable from
getting caught when installing the base metal.
CCFT cable
Inverter cable
Power supply cable
Switch cable
LCD cable
Fig. 1
Fig. 2
Power supply cable
Power supply cable
Switch cable
Fig. 3
Fig. 4
CHAPTER6. BLOCK DIAGRAM/UNIT TERMINSL
LCD UNIT
LANP
15 inch LCD
LANP
INVERTER
1
LCD SIGNAL INPUT
2
JP5
4
CN-JP5
3
J4
INTERFACE
UNIT
5
J1
RGB, H/V
IN PUT
KEY-SWITCH UNIT
POWER UNIT
AC 100V
INPUT
AC SW
AC SOKET
1
5
Connector Symbol Function
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