DOWNLOAD LG 42LY3DE-AA (CHASSIS:LB75B) Service Manual ↓ Size: 5.98 MB | Pages: 74 in PDF or view online for FREE

- 5 -

IC Remove/Replacement
Some  chassis  circuit  boards  have  slotted  holes  (oblong)  through
which  the  IC  leads  are  inserted  and  then  bent  flat  against  the
circuit foil. When holes are the slotted type, the following technique
should be used to remove and replace the IC. When working with
boards  using  the  familiar  round  hole,  use  the  standard  technique
as outlined in paragraphs 5 and 6 above.

Removal
1.  Desolder and straighten each IC lead in one operation by gently

prying  up  on  the  lead  with  the  soldering  iron  tip  as  the  solder
melts.

2.  Draw  away  the  melted  solder  with  an  anti-static  suction-type

solder removal device (or with solder braid) before removing the
IC.

Replacement
1.  Carefully insert the replacement IC in the circuit board.
2.  Carefully  bend  each  IC  lead  against  the  circuit  foil  pad  and

solder it.

3.  Clean the soldered areas with a small wire-bristle brush.

(It is not necessary to reapply acrylic coating to the areas).

"Small-Signal" Discrete Transistor
Removal/Replacement
1.  Remove the defective transistor by clipping its leads as close as

possible to the component body.

2.  Bend into a "U" shape the end of each of three leads remaining

on the circuit board.

3.  Bend into a "U" shape the replacement transistor leads.
4.  Connect  the  replacement  transistor  leads  to  the  corresponding

leads  extending  from  the  circuit  board  and  crimp  the  "U"  with
long  nose  pliers  to  insure  metal  to  metal  contact  then  solder
each connection.

Power Output, Transistor Device
Removal/Replacement
1.  Heat and remove all solder from around the transistor leads.
2. Remove the heat sink mounting screw (if so equipped).
3.  Carefully remove the transistor from the heat sink of the circuit

board.

4.  Insert new transistor in the circuit board.
5. Solder each transistor lead, and clip off excess lead.
6.  Replace heat sink.

Diode Removal/Replacement
1.  Remove  defective  diode  by  clipping  its  leads  as  close  as

possible to diode body.

2.  Bend  the  two  remaining  leads  perpendicular  y  to  the  circuit

board.

3.  Observing  diode  polarity,  wrap  each  lead  of  the  new  diode

around the corresponding lead on the circuit board.

4.  Securely crimp each connection and solder it.
5.

Inspect  (on  the  circuit  board  copper  side)  the  solder  joints  of

the two "original" leads. If they are not shiny, reheat them and if
necessary, apply additional solder.

Fuse and Conventional Resistor
Removal/Replacement
1.  Clip each fuse or resistor lead at top of the circuit board hollow

stake.

2.  Securely  crimp  the  leads  of  replacement  component  around

notch at stake top.

3.  Solder the connections.

CAUTION: Maintain  original  spacing  between  the  replaced
component  and  adjacent  components  and  the  circuit  board  to
prevent excessive component temperatures.

Circuit Board Foil Repair
Excessive  heat  applied  to  the  copper  foil  of  any  printed  circuit
board  will  weaken  the  adhesive  that  bonds  the  foil  to  the  circuit
board  causing  the  foil  to  separate  from  or  "lift-off"  the  board.  The
following  guidelines  and  procedures  should  be  followed  whenever
this condition is encountered.

At IC Connections
To  repair  a  defective  copper  pattern  at  IC  connections  use  the
following  procedure  to  install  a  jumper  wire  on  the  copper  pattern
side  of  the  circuit  board.  (Use  this  technique  only  on  IC
connections).

1.  Carefully  remove  the  damaged  copper  pattern  with  a  sharp

knife. (Remove only as much copper as absolutely necessary).

2.  carefully  scratch  away  the  solder  resist  and  acrylic  coating  (if

used) from the end of the remaining copper pattern.

3.  Bend a small "U" in one end of a small gauge jumper wire and

carefully crimp it around the IC pin. Solder the IC connection.

4.  Route  the  jumper  wire  along  the  path  of  the  out-away  copper

pattern and let it overlap the previously scraped end of the good
copper  pattern.  Solder  the  overlapped  area  and  clip  off  any
excess jumper wire.

At Other Connections
Use  the  following  technique  to  repair  the  defective  copper  pattern
at  connections  other  than  IC  Pins.  This  technique  involves  the
installation  of  a  jumper  wire  on  the  component  side  of  the  circuit
board.

1.  Remove the defective copper pattern with a sharp knife.

Remove at least 1/4 inch of copper, to ensure that a hazardous
condition will not exist if the jumper wire opens.

2.  Trace  along  the  copper  pattern  from  both  sides  of  the  pattern

break  and  locate  the  nearest  component  that  is  directly
connected to the affected copper pattern.

3.  Connect  insulated  20-gauge  jumper  wire  from  the  lead  of  the

nearest component on one side of the pattern break to the lead
of the nearest component on the other side.
Carefully crimp and solder the connections.
CAUTION: Be sure the insulated jumper wire is dressed so the
it does not touch components or sharp edges.

- 6 -

NOTE : Specifications and others are subject to change without notice for improvement.

No. 

Item 

Specification 

Remark 

1. 

Broadcasting system

PAL-B/B, DTV : DVB-T

2. 

Available Channel

1) VHF : 00 ~ 12

2) UHF : 20 ~ 75

3)  CATV : 02 ~ 44 

4) DTV : 06 ~12, 27 ~ 69 

3. 

Tuner IF

1) PAL  : 38.90MHz(Picture),

34.40MHz(Sound)

2) DVB-T : 36.125MHz

4

Input Voltage

AC 100 ~ 240 V, 50/60Hz

Mark : 240V, 50Hz

5.

Screen Size

42 inch Wide(1920 x 1080)

42LY3DE

47 inch Wide(1920 x 1080)

47LY3DE

6.

Aspect Ratio

16:9

7.

Module

LC420WU5-SLA2

42LY3DE

LC470WU6-SLA2

47LY3DE

8.

Operating Environment

1) Temp   :  0 ~ 40 deg

2) Humidity :   ~ 80 %

9.

Storage Environment

1) Temp   : -20 ~ 60 deg

2) Humidity :   ~ 85 %

This  spec  sheet  is  applied  to  the  42"/47"  LCD  TV  used  LB75B
chassis.  

Each part is tested as below without special appointment  

2.1 Temperature :  25±5°C(77±9°F), CST : 40±5°C
2.2 Relative Humidity : 65±10% 
2.3 Power Voltage :  Standard input voltage 

(100~240V@ 50/60Hz)  
• Standard Voltage of each products is marked by models 

2.4 Specification and performance of each parts are followed

each  drawing  and  specification  by  part  number  in
accordance with SBOM .  

2.5 The receiver must be operated for about 20 minutes prior

to the adjustment.

3.1 Performance : LGE TV test method followed.
3.2 Demanded other specification 

Safety : CB  specification

3.3 EMC : CISOR 13 specification

- 7 -

No

Item

Min

Typ

Max

Unit

Remark

1. 

White peak brightness

450

550

cd/m

2

42LY3DE

400

550

cd/m

2

47LY3DE

2. 

Contrast ratio

cd/m

2

N/A

3. 

Brightness uniformity

80

%

Full white

4. 

Color coordinate

RED

X

Typ.

0.638

Typ.

Y

-0.03

0.340

+0.03

GREEN

X

0.279

Y

0.611

BLUE

X

0.146

Y

0.062

WHITE

X

0.272

Y

0.278

5.

Color coordinate uniformity

N/A

6.

Contrast ratio    

600:1

800:1

42/47LY3DE

1100:1

1600:1

With A.I 42/47LY3DE

7.

Color Temperature

Cool

11,000

12,000

13,000

<Test Condition>

Medium

9,300

HDMI input,

Warm

6,500

85% Full white pattern

8.

Color Distortion, DG

10.0

%

9.

Color Distortion, DP

10.0

deg

10.

Color S/N, AM/FM

43.0

dB

11.

Color Killer Sensitivity

-80

dBm

- 8 -

Peak & average Brightness & Contrast measure standard specification
- White Peak brightness measure specification

1) In non-impressed condition, measure peak brightness displayable as much as possible LCD module.
2) Measuring instrument: CA-210 or a sort of Color Analyzer. 
3) Pattern Generator : VG-828 or a sort of digital pattern generator (displayable Full White & 1/25 White Window pattern)
4) Measure condition

-  Test pattern: in center, 1/5(H)x1/5(V) of Window Pattern (white pattern in non-impressed condition)
-  SET condition : Contrast & Brightness Level 100%
-  Environment condition : Dark room in the non outside light 
-  Video menu option condition

5) Measurement

-  Do  heat-run  LCD  module  at  30minutes  in  normal  temperature  (25°C)  by  using  full  white  pattern  of  15%  signal  level(38  gray

level).

-  Impress test pattern signal in 1/5(H)x1/5(V) White Window of 100%(255Gray Level)
-  measure 3 times brightness of central white window, and mark peak brightness in max brightness degree 
-  measure the same condition in video signal /RGB signal.

1) Impress 100%(255Gray Level) full white pattern at the same peak brightness measurement.
2) Measure average brightness in 9 points. 

1) Test display signal : 30x30 dots White Window signal & all Black Raster signal
2) Dark room measure condition : Using touch type Color analyzer CA-100 Dark room in the non outside light 
3) Bright room measure condition :  In bright room of 150Lx illumination in the panel surface, locate a source of light on the above

45°of the panel surface.

4) Measure method

- In standard test condition, impress 30x30 dots White Window Pattern signal .

Measure center peak brightness degree Lw of white window

- Impress black Raster signal as contrast ratio measurement signal.

Measure black brightness degree Lb of PDP central 
Calculate the following numerical formula.
Contrast ratio = Lw / Lb

Signal

Picture Mode

XD

Black Level

RF

PAL

USER1

On

N/A

AV

PAL

USER1

On

Low

Component

720P

USER1

On

N/A

RGB

1024x768

USER1

N/A

N/A

HDMI

DTV 720P

USER1

On

High

1                   4                     7

2                   5                     8

3                   6                     9