Sharp LL-T1820 (serv.man5) Service Manual ▷ View online
PC-UM10M
LL-T1820-H/B TROUBLE SHOOTING
4 – 1
CHAPTER 4. TROUBLE SHOOTING
(Yes)
(Yes)
(Yes)
(Yes)
(Yes)
(Yes)
Green LED comes on when the power button is
pressed?
pressed?
The screen is displayed properly in each video
mode?
mode?
AC cable is connected to the power supply
unit?
unit?
Input signal port is the one to which analog
signal cable is connected?
signal cable is connected?
Test terminals LD416, LD417, and LD418 are
DC+3.3V?
DC+3.3V?
Test terminal LD628 changes its level when
POWER switch is turned on and off?
POWER switch is turned on and off?
Press INPUT key to switch over to the
correct input signal port.
correct input signal port.
Check the power supply unit and power
supply cable and their connections.
supply cable and their connections.
Check DC+5V power supply line (DV5A)
and POWER_CTL1 signal and circuits
around 0808.
and POWER_CTL1 signal and circuits
around 0808.
Check DC+5V power supply line (AV5) and
POWER_CTL1 signal and circuits around
0808.
POWER_CTL1 signal and circuits around
0808.
Check MAINPW signal and areas around
CN800.
CN800.
Remove the analog signal cable. After a short
while time, the LED color changes form green
to orange.
while time, the LED color changes form green
to orange.
(Yes)
(Yes)
(No)
(No)
(Yes)
(Yes)
(No)
(No)
(No)
(No)
(Yes)
(Yes)
(No)
(No)
(No)
(No)
(No)
(Yes)
(No)
(Yes)
(No)
(Yes)
(Yes)
(No)
(No)
(No)
Perform 1
B/L is lit?
No error.
Check AC cable connection.
Check power supply unit switch.
Check circuits around IC600.
Check circuits around IC400.
Check RESET circuit around IC602.
Check IC601 and clock circuit around X600.
Check SW100 and circuits around IC100.
The power supply unit is switched on?
SW100 is on 1st pin side?
Test terminal LD805 is DC+5V?
8th pin of 0808 is DC+5V?
4th pin of IC602 is in H level (DC+5 V)?
Test terminal LD809 is DC+5V?
C610-side terminal signal of X600 is normal?
Test terminal LD634 is DC+3.3V?
1
Perform 2
Perform 3
Perform 4
PC-UM10M
LL-T1820-H/B TROUBLE SHOOTING
4 – 2
(No)
(No)
(No)
(No)
(Yes)
(Yes)
(Yes)
(No)
(Yes)
(Yes)
(No)
(Yes)
(Yes)
(No)
(Yes)
(No)
(Yes)
(No)
(Yes)
(No)
(Yes)
(Yes)
(Yes)
(No)
(No)
The port from which the analog signal cable
was removed is the input signal port selected?
was removed is the input signal port selected?
48th pin and 49th pins of IC601 are in H level
(DC+3.3V)?
(DC+3.3V)?
LD618 and LD621 are in H level (about
DC+1.9V)?
DC+1.9V)?
LD801 is less than DC+1.0V at maximum
brightness?
brightness?
1st pin of CN2, CN3, CN4, CN5, CN6, and CN7
on inverter PWB unit is about 750 Vrms? (Use
caution not to get electric shock accident. Use
a high-voltage probe (more than 100:1) for
measuring voltage.)
on inverter PWB unit is about 750 Vrms? (Use
caution not to get electric shock accident. Use
a high-voltage probe (more than 100:1) for
measuring voltage.)
Check analog signal cable and CN100
(CN200).
(CN200).
Check SDA and SCL signals and circuits
around IC401 and IC601.
around IC401 and IC601.
Press INPUT key to switch over to the
correct input signal port.
correct input signal port.
Check the power unit and cable and their
connections, and DC+12V power supply
line.
connections, and DC+12V power supply
line.
Check BL_EN signal and circuits around
CN801.
CN801.
Check BRT_VR signal and circuits around
IC603.
IC603.
Signal waveforms of test terminals LD303,
LD304 (LD310, LD311) are normal?
LD304 (LD310, LD311) are normal?
Signal waveforms of test terminals LD305,
LD306 (LD312., LD313) are normal?
LD306 (LD312., LD313) are normal?
Signal waveforms of 31st and 32nd pins of
IC401 are normal?
IC401 are normal?
Check SW PWB and SW cable and their
connections.
connections.
48th pin of IC601 is in H level (DC+3.3V)?
continued from 1
LD618 is H in level (about DC+1.9V)?
Check SW PWB and SW cable connections.
Test terminal LD804 is DC+12V?
LD800 is in H level (DC+5V)?
Check lamp inside LCD module.
Check circuits around IC601.
Check Q600 and its surrounding circuits.
Replace inverter PWB unit with a new one.
Check circuits around IC601.
Check Q600 and its surrounding circuit.
Check circuits around IC300 and IC301.
2
3
PC-UM10M
LL-T1820-H/B TROUBLE SHOOTING
4 – 3
(No)
(No)
(No)
(Yes)
(Yes)
(No)
(No)
(Yes)
(No)
(Yes)
(Yes)
(No)
(Yes)
(No)
(Yes)
(No)
(Yes)
(Yes)
(Yes)
(No)
(No)
(No)
(Yes)
(Yes)
(Yes)
(Yes)
(No)
(Yes)
(No)
(No)
(No)
(Yes)
(No)
(No)
(Yes)
(No)
(Yes)
(Yes)
Check DC+5V power supply line (AV5) ,
POWER_CTL1 signal, and circuits around
Q808.
POWER_CTL1 signal, and circuits around
Q808.
Check DC+5V power supply line (PV5) ,
POWER_CTL3 signal, and circuits around
Q800.
POWER_CTL3 signal, and circuits around
Q800.
Check the power supply unit and cable and
their connections, and POWER_CTL1
their connections, and POWER_CTL1
Check DC+2.5V power supply line (DV25),
POWER_CTL1 signal, and circuits around
IC800.
POWER_CTL1 signal, and circuits around
IC800.
Check DC+12V power supply line (LCDV),
POWER_CTL2 signal, and circuits around
Q800.
POWER_CTL2 signal, and circuits around
Q800.
Check OSC500 and clock circuit around
IC502.
IC502.
Clock (R517) and DE (R515) signal outputs
are normal?
are normal?
ADJUSTMENT and MODE SELECT are set
properly?
properly?
Signal waveform of test terminal LD510 is
normal?
normal?
ADJUSTMENT and MODE SELECT are set
properly?
properly?
Adjust according to "screen adjustment
procedure".
procedure".
Adjust according to "screen adjustment
procedure".
procedure".
Check circuits around IC300, IC301, and
IC401.
IC401.
Check circuits around IC701, and CN700
and LCD module.
and LCD module.
Check DC+5V power supply line (DV5A),
POWER_CTL1 signal, and circuits around
Q808.
POWER_CTL1 signal, and circuits around
Q808.
Test terminals LD419, LD515, and LD700 are
DC+3.3V?
DC+3.3V?
Signal waveform of test terminal LD500 is
normal?
normal?
Test terminals LD416, LD417, and LD418 are
DC+3.3V?
DC+3.3V?
8th pin of Q808 is DC+5V?
Test terminal LD809 is DC+5V?
Test terminal LD810 is DC+5V?
Test terminal LD807 is DC+12V?
Test terminal LD509 is DC+2.5V?
TP801 is DC+12.0V?
36th pin of LC601 is in H level (DC+5V)?
The entire LCD screen is white?
The entire LCD is black?
The size of LCD screen is abnormal?
LCD screen jitters or flickers?
Check circuits around IC400.
Check circuits around IC402.
Check circuits around IC601.
Test terminal of LD701 is DC+12V?
Check circuits around X600 and IC601.
Check circuits around IC501.
Check circuits around CN700.
Check circuits around IC401.
Check circuits around IC501.
4
PC-UM10M
LL-T1820-H/B TROUBLE SHOOTING
4 – 4
(No)
(No)
(No)
(Yes)
(Yes)
(Yes)
(Yes)
(No)
(No)
(Yes)
(No)
(No)
(Yes)
(Yes)
(Yes)
(No)
(Yes)
(No)
(No)
(Yes)
(No)
(Yes)
(No)
(Yes)
(No)
(Yes)
(Yes)
(No)
(Yes)
(Yes)
(No)
(No)
(Yes)
(Yes)
GAIN CONTROL and WHITE BALANCE
are set properly?
are set properly?
Analog color signal output (C302, C304,
C306, C317, C320, and C322) is normal?
C306, C317, C320, and C322) is normal?
Digital color signal output of IC401(ID0
ID47) is normal?
ID47) is normal?
Digital color signal output of IC501 (OD0
OD47) is normal?
OD47) is normal?
Check circuits around IC701, and CN700
and LCD module.
and LCD module.
Check circuits around IC401, IC403, and
IC601.
IC601.
Digital color signal output of IC401 (ID0
ID47) is normal?
ID47) is normal?
Press INPUT key to switch over to the
correct input signal port.
correct input signal port.
Check CN100 and 200, and signal source
and digital signal cable.
and digital signal cable.
Check circuits around IC100, IC102, IC103,
IC200, and IC201.
IC200, and IC201.
Check CN100 and 200, and signal source
and digital signal cable.
and digital signal cable.
Display is normal in composite sync and sync-
on-green signal input.
on-green signal input.
AUTO function of GAIN CONTROL operates
properly?
properly?
Input signal port is the one to which digital
signal cable is connected?
signal cable is connected?
Waveforms of IC103s and 201s 5th and 6th
pins change normally when resolution is
changed?
pins change normally when resolution is
changed?
Test terminals LD100, LD101, LD200, LD201,
LD202, LD203, LD204, LD205 are DC+3.3V?
LD202, LD203, LD204, LD205 are DC+3.3V?
CN100 and 200 signals (at 1st, 2nd, 9th, 10th,
17th, 18th, 23rd, and 24th pins) are normal?
17th, 18th, 23rd, and 24th pins) are normal?
IC101 and IC203 signal output (ID0 ID47,
HIS, IVS,ICK, IACT) are normal?
HIS, IVS,ICK, IACT) are normal?
LCD screen color is abnormal?
Input is changed over properly?
No error.
Display is normal in analog input?
TP100 and 200 are in H level (DV+5V)?
Check circuits around IC501.
Adjust according to "screen adjustment
procedure".
procedure".
Check circuits around IC401.
Check circuits around IC401 and IC501.
Check circuits around IC501 and IC701.
Check circuits around IC401 and IC403.
Check circuits around IC601.
check circuits around IC601 and IC604.
Check circuits around IC401.
First, check with analog signal input.
Check circuits around IC400.
Check circuits around IC101 and IC203.
continued from 4
5
Display