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PC-UM10M

LL-T1820-H/B   DISASSEMBLY AND ASSEMBLY

3 – 1

1) Remove the four screws 

A

 and remove the display 

1

 from the stand 

2

. 

1)  Remove the seven screws 

B

 and remove the rear cabinet 

3

.

2)  Remove the seven screws 

C

 and remove the PWB shield 

4

.

3)  Remove the harnesses 

D

, 

F

. Remove the three screws 

E

 and remove the

     *** PWB 

5

.

4)  Remove the harnesses 

G

, 

H

. Remove the 18 screws and remove the main

     PWB 

6

.

5)  Remove the harness 

J

. Remove the five screws 

K

 and remove the power

     supply PWB 

7

.

6)  Remove the eight screws 

L

 and remove the angle 

8

 from the LCD unit 

9

.

7)  Remove the front cabinet 

F

.

8)  Remove the seven harnesses 

N

. Remove the three screws 

O

 and remove

      the inverter PWB 

G

.

9)  Remove the six screws 

P

, 

H

, 

Q

. Remove the angles 

H

, 

I

, 

J

 from the 

      LCD unit 

K

.

PC-UM10M

LL-T1820-H/B   DISASSEMBLY AND ASSEMBLY

3 – 2

1)

Remove the five screws 

A

 and separate the *** 

1

 from the base 

2

.

2)

Remove the cover 

3

.

3)

Remove the six screws 

B

 and remove the *** 

4

.

4)

Remove one screw 

C

 and remove the cover 

5

.

5)

Remove the two screws 

D

 and remove the *** 

6

.

6)

Remove the two screws 

E

 and remove the *** 

7

.

7)

Pull the *** 

9

 out of the *** 

8

.

8)

Remove the two screws 

F

 and remove the *** 

F

.

9)

Remove one screw 

G

 and remove the *** 

G

.

10) Remove the three screws 

H

 and remove the *** 

H

.

11) Remove the 17 screws and remove the *** 

I

, *** 

J

 and *** 

K

.

PC-UM10M

LL-T1820-H/B   TROUBLE SHOOTING

4 – 1

(Yes)

(Yes)

(Yes)

(Yes)

(Yes)

(Yes)

Green LED comes on when the power button is 
pressed?

The screen is displayed properly in each video 
mode?

AC cable is connected to the power supply 
unit?

Input signal port is the one to which analog 
signal cable is connected?

Test terminals LD416, LD417, and LD418 are 
DC+3.3V?

Test terminal LD628 changes its level when 
POWER switch is turned on and off?

Press INPUT key to switch over to the 
correct input signal port.

Check the power supply unit and power 
supply cable and their connections.

Check DC+5V power supply line (DV5A) 
and POWER_CTL1 signal and circuits  
around 0808.

Check DC+5V power supply line (AV5) and 
POWER_CTL1 signal and circuits around 
0808.

Check MAINPW signal and areas around 
CN800.

Remove the analog signal cable. After a short 
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?

48th pin and 49th pins of IC601 are in H level 
(DC+3.3V)?

LD618 and LD621 are in H level (about 
DC+1.9V)?

LD801 is less than DC+1.0V at maximum 
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.)

Check analog signal cable and CN100 
(CN200).

Check SDA and SCL signals and circuits 
around IC401 and IC601.

Press INPUT key to switch over to the 
correct input signal port.

Check the power unit and cable and their 
connections, and DC+12V power supply 
line.

Check BL_EN signal and circuits around 
CN801.

Check BRT_VR signal and circuits around 
IC603.

Signal waveforms of test terminals LD303, 
LD304 (LD310, LD311) are normal?

Signal waveforms of test terminals LD305, 
LD306 (LD312., LD313) are normal?

Signal waveforms of 31st and 32nd pins of 
IC401 are normal?

Check SW PWB and SW cable and their 
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