Read Sharp LL-171ME Service Manual online
LL-171ME
TROUBLESHOOTING
4 – 1
CHAPTER 4. TROUBLESHOOTING
Go to item
(No)
(Yes)
(Yes)
LED does not come on.
Go to item
Power LED (power supply indicator)
does not come on.
does not come on.
Power LED remains in orange,
does not turn green.
does not turn green.
(No)
(Yes) Go to item
Backlight does not come on.
(No)
(Yes) Go to item
OSD is not displayed when MENU
or INPUT is pressed.
or INPUT is pressed.
Go to item
(No)
(Yes)
(Yes) Replace Fuse (F1).
12 V (L1) is not applied.
LCD defective
12 V (F1) is not output.
(No)
LED remains in orange.
(Yes) Go to item
(No)
(Yes) Go to item
Go to item
Power voltage 3.3 V (F3) is not output.
(No)
(Yes)
Power voltage 5.0 V (F2) is not output.
Check PW166 (U21) and
circuits around it.
circuits around it.
(No)
Perform "All reset" (Press and hold
down Enter and Menu buttons
while turn on power supply.)
down Enter and Menu buttons
while turn on power supply.)
HW-PW signal (Pin 1 of J3) does
not become low when power
button is pressed.
not become low when power
button is pressed.
(No)
(No)
Check U9 and circuits around it.
Reset signal is active (R32 is
high) when power supply is
turned on?
high) when power supply is
turned on?
(Yes)
(No)
Power LED control signals (R15,
R16) do not become high.
R16) do not become high.
(Yes)
(No)
PW166 operation CLK (Y1)
generates clock (14.318 MHz)?
generates clock (14.318 MHz)?
(Yes)
Check PW166 (U21) and flash
ROM (U23) peripheral circuits.
ROM (U23) peripheral circuits.
Check U5, circuits around
it, and IIC bus.
it, and IIC bus.
Check generator (Y1) and
circuits around it.
circuits around it.
(No)
Either LED control signal
conductor (R15) or power LED
red (R16) is not high.
conductor (R15) or power LED
red (R16) is not high.
(Yes)
Check power switch PWB
connector.
connector.
(No)
PW166 operation CLK (Y1)
generates clock (14.318 MHz)?
generates clock (14.318 MHz)?
(Yes)
(No)
Flash ROM (U23) is not normal?
(Yes)
Rewrite in flash ROM
(U23).
(U23).
(No)
PW166 operation CLK (Y1)
generates clock (14.318 MHz)?
generates clock (14.318 MHz)?
(Yes)
Check generator (Y1) and
circuits around it.
circuits around it.
Backlight does not come on.
(No)
Backlight power supply VDD
(Pins 1, 2 and 3 of J1) output
voltage (12 V)?
(Pins 1, 2 and 3 of J1) output
voltage (12 V)?
(Yes)
Check U2 and circuits
around them.
around them.
(No)
Backlight ON signal VEE (Pin 8
of J1) outputs signal (high)?
of J1) outputs signal (high)?
(Yes)
Check U5 and circuits
around it.
around it.
(No)
Backlight control signal VCON
(Pin 7 of J1) outputs voltage (0 -
3.3 V)?
(Pin 7 of J1) outputs voltage (0 -
3.3 V)?
(Yes)
Check U5 and circuits
around it.
around it.
Check inverter connection cable
and inverter unit.
and inverter unit.
OSD is not displayed.
(Yes)
Adapter defective
(No)
Adapter output is normal (approx.
12 V) and output voltage is stable?
12 V) and output voltage is stable?
(No)
(No)
LCD 5V (SW-LCD: L24) is
output?
output?
(Yes)
Check U10 and circuits
around it.
around it.
(No)
LCD display signal is output from
PW166 (U21)?
PW166 (U21)?
(Yes)
(Yes)
Check 12-V line for shorting.
HW-PW signal circuit is normal?
(Yes)
(No)
Power switch PWB switch
(SW9K) clicks.
(SW9K) clicks.
(Yes)
Replace power switch PWB.
(Yes)
Check PW166 (U21) and
circuits around it.
circuits around it.
(No)
Check power switch PWB
connection cable connector for
improper insertion or cable for
being caught.
connection cable connector for
improper insertion or cable for
being caught.
(Yes)
Reinsert or replace if cable
is broken due to being
caught.
is broken due to being
caught.
Replace power supply button
which is fit into power supply
switch (SW9K).
which is fit into power supply
switch (SW9K).
(No)
Check HW-PW signal
circuit and around it.
circuit and around it.
(No)
Check LCD relay PWB
connection cable for proper
connection or broken wire.
connection cable for proper
connection or broken wire.
LCD control signal is output (LCD
relay PWB)?
Check for fit between LCD unit
and LCD relay PWB.
relay PWB)?
Check for fit between LCD unit
and LCD relay PWB.
Power voltage 5V (F2) is not output?
No screen appears.
.
.
.
.
.
.
.
.
Go to item
(Yes)
Power voltage 5.0 V (Pin 3 of UP3)
is not output.
is not output.
.
Go to item
.
Check generator (Y1) and
circuits around it.
circuits around it.
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