Sharp LL-T1803 (serv.man14) Service Manual ▷ View online
LL-T1803-E/P
TROUBLESHOOTING
5 – 1
CHAPTER 5. TROUBLESHOOTING
A
The power is not
supplied.
When the power switch is
turned,
does the LCD turn green?
Does the back light turn on?
NO
NO
NO
NO
NO
NO
YES
YES
YES
YES
YES
Check the analog cable input
and the digital cable input.
Normal
Normal
Abnormal
Abnormal
Check each pin of JP4.
Replace the analog/
digital cable(s).
Check the inverter PWB unit.
(Note) When checking the output side,
be careful of the high voltage.
(1400Vrms when starting)
Check the output circuit to JP4.
When +12V is NG, main PWB
Replace the LCD module lamp.
Replace the
inverter PWB unit.
The LED turns red.
The LED turns orange.
Check the LED for breakage.
Check the path between
JP2 (8pin) and U12 (24pin).
Check the cable for disconnection.
Check the path between
JP2 (8pin) and U12 (24pin).
Check the cable for disconnection.
Replace any abnormal part.
(Main PWB, SW PWB, cable)
Is the machine in the power save mode?
(Is the sync signal inputted?)
Is the PC power turned off ?
Is the RGB cable disconnected ?
Is the sync signal not outputted from
the RGB cable ?
Is the Input key set to the analog,
digital, input PC side ?
(Is the sync signal inputted?)
Is the PC power turned off ?
Is the RGB cable disconnected ?
Is the sync signal not outputted from
the RGB cable ?
Is the Input key set to the analog,
digital, input PC side ?
Is the sync signal inputted
to the main PWB?
Replace the analog
and the digital cables.
Check the input power system.
AC adapter
Normal?
Connected?
Is +5V (VCC) supplied to MPU (U12) ?
LED
Check the LED for breakage.
Check the path between JP2 (8pin)
and U12 (24pin).
Check the cable for disconnection.
AC adapter
Normal?
Connected?
Is +5V (VCC) supplied to MPU (U12) ?
LED
Check the LED for breakage.
Check the path between JP2 (8pin)
and U12 (24pin).
Check the cable for disconnection.
Replace any abnormal parts.
( AC adapter, Main PWB,
Switch PWB)
LL-T1803-E/P
TROUBLESHOOTING
5 – 2
A
2
Display abnormality
Check the analog cable and the digital cable.
Change the display mode and check the
display conditions.
Execute the microcomputer reset, and check that the display is changed.
(Press and hold the MENU button and the SELECT button,
and press the POWER SW.)
Normal
Normal
Abnormal
Abnormal
Normal
Abnormal
Normal
Abnormal
Replace the analog and
the digital cables.
The display
remains black.
The display
remains white.
The display flickers.
The text display flickers.
Abnormal colors
Check the following signals.
Is the module control outputted ?
Check the LCD control signal at U10, U11,
U12, U8, and U13, and the microcomputer
control circuit peripheral for any abnormality.
Is the module control outputted ?
Check the LCD control signal at U10, U11,
U12, U8, and U13, and the microcomputer
control circuit peripheral for any abnormality.
Digital
Analog
Can CLOCK and
PHASE be adjusted?
When set to H-POS and V-POS,
if the BLACK LEVEL or CONT
is changed,
dose the abnormal section move
on the display?
Switch PWB
abnormality
Main PWB abnormality
LCD panel abnormality
Cable abnormality
Display