Read Sharp LL-T1500A (serv.man21) Service Manual online
CHAPTER 4. TROUBLESHOOTING (for checking PWBs)
Make sure that the following accessory cables are connected properly.
In addition, make sure that the video mode of the personal computer is properly set to the signal timing supported by this machine.
In addition, make sure that the video mode of the personal computer is properly set to the signal timing supported by this machine.
ACCESSORY CABLES
·
Power cable
·
USB cable
Check for defective parts in the
following manner.
following manner.
Does the light of the LED change from orange
to green when pressing the power-on switch?
to green when pressing the power-on switch?
No
(1) See <An error occurs when detecting the
synchronizing signal.>
synchronizing signal.>
Remove the RGB cable. Does LED
come on in orange after for a while?
come on in orange after for a while?
(2) See <An error occurs when using the
Power Save mode>
Power Save mode>
Connect the RGB cable.
Does the backlight come on?
Does the backlight come on?
(3) See <Backlight goes out improperly>.
Does the screen display normally
in each video mode?
in each video mode?
(4) See <Screen error>
Do the USB units operate normally?
(5) See <USB error>.
Yes
No error
(1) <An error occurs when detecting the synchronizing signal>
Is DC+12V outputted from the
power supply unit?
power supply unit?
Check the power supply unit and
fuses (power supply unit).
fuses (power supply unit).
Is B13 at DC+12V?
Check the DC+12V power line (12V), and the
power supply circuit for the fuse F1.
power supply circuit for the fuse F1.
Is the signal input of the 5th pin of
the U17 at low level (0V)?
the U17 at low level (0V)?
Check the power supply circuit for the operation PWB
(operation PWB and cables) and that for the U17.
(operation PWB and cables) and that for the U17.
Is the 4th pin of the U17 at DC+15V?
Check the DC+15V power supply line (5Va)
and the power supply circuit for the U17.
and the power supply circuit for the U17.
Is the signal input of the 11th pin of
the U10 at low level (0V)?
the U10 at low level (0V)?
Check the REST circuit for the U10.
Is the signal input of the 22nd pin of the
U10 normal? (See Waveform diagram 1.)
U10 normal? (See Waveform diagram 1.)
Check the clock circuit for the U10 and X1.
Is the signal input of the 4th pin of
the U16 at low level (0 V)?
the U16 at low level (0 V)?
Check the power supply circuit for the operation PWB
(operation PWB and cables) and that for the U16.
(operation PWB and cables) and that for the U16.
Is the 8th pin of the U16 at DC+12V?
Check the DC+12V power line (12 Va) and
the power supply circuit for the U16.
the power supply circuit for the U16.
Is the signal input of the 17th pin of the U10
normal? (See Waveform diagrams 2, 3.)
normal? (See Waveform diagrams 2, 3.)
Check the signal cable and the synchronizing
signal processing circuit for the U10 and U21.
signal processing circuit for the U10 and U21.
Is the signal output of the 27th pin of
the U10 at low level (0 V)?
the U10 at low level (0 V)?
Check the microprocessor control circuit
for the U10.
for the U10.
Is the signal output of the 42nd pin of
the U10 at high level (DC+5V)?
the U10 at high level (DC+5V)?
Check the microprocessor control circuit
for the U10.
for the U10.
Check the operation PWB and related
parts (LED and cables).
parts (LED and cables).
Yes
Yes
Yes
Yes
No
No
No
No
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
No
No
No
No
No
No
No
No
Yes
Yes
Yes
Yes
Yes
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