DOWNLOAD LG 42LF2500 / 42LF2510 (CHASSIS:LD91A) Service Manual ↓ Size: 5.78 MB | Pages: 78 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.

This specification is applied to the LCD TV used LD91A
chassis.

Each part is tested as below without special appointment.

1) Temperature :  25±5ºC (77±9ºF), CST : 40±5ºC
2) Relative Humidity :  65±10%
3) Power Voltage : Standard input voltage (100-240V@50/60Hz)

* Standard Voltage of each products is marked by models.

4) Specification and performance of each parts are followed

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

5) The receiver must be operated for about 5 minutes prior to

the adjustment.

1) Performance: LGE TV test method followed 
2) Demanded other specification 

- Safety: CE, IEC specification
- EMC:CE, IEC 

No

Item Specification 

Remark

1

Screen Device

42” wide color display module 

LCD

2

Aspect Ratio

16:9

3

LCD Module 

42” TFT LCD FHD

LGD

4

Storage Environment 

Temp. : -20 ~ 60 deg

Humidity : 10 ~ 90 %

5

Input Voltage 

AC100-240V~, 50/60Hz

6

Power Consumption

FHD

Typ : 167.5, Max : 185.28

7

Module Size

983 (H) x 576 (V) x 46 (D)

8

Pixel Pitch

0.4845 mm(D)

9

Back Light

EEFL

10

Display Colors

1.06Billion(FHD LGD),16.7M (others)

11

Coating

3H, AG

- 7 -

1) Standard Test Condition (The unit has been ‘ON’)
2) Stable for approximately 30 minutes in a dark environment at 25±2ºC
3) The values specified are at approximate distance 50Cm from the LCD surface
4) Ta=25±2ºC, VLCD=12.0V, fV=60Hz, Dclk=74.25MHz VBR_A=1.65V,ExtVBR_B=100%

No. Item Specification 

Min.

Typ.

Max.

Remark

1.

Viewing Angle<CR>10> 

Right/Left/Up/Down 

178

Degree

2.

Luminance Luminance 

(cd/m

2

)

400 500

Variation -

1.3 

MAX 

/MIN

3.

Contrast Ratio 

CR 

1000 

1400

4.

CIE Color Coordinates   

White 

WX

0.279 

WY 0.292

Typ 

RED Xr

0.638

±0.03

Yr

0.334

Green Xg

0.290

Yg

0.606

Blue Xb 

0.144

Yb  

0.064

No

Specification

Remark

Resolution

H-freq(kHz)

V-freq(Hz)

1.

720x480 15.73 

60.00 

SDTV,DVD 

480i

2.

720x480 15.63 

59.94 

SDTV,DVD 

480i

3.

720x480

31.47

59.94 480p

4.

720x480

31.50

60.00 480p

5.

720x576 

15.625 

50.00 

SDTV,DVD 625 Line

6.

720x576 31.25 

50.00

HDTV 

576p

7.

1280x720

45.00

50.00 HDTV 

720p

8.

1280x720

44.96

59.94 HDTV 

720p

9.

1280x720 45.00 

60.00 

HDTV 

720p

10.

1920x1080 31.25 

50.00 

HDTV 

1080i

11.

1920x1080

33.75

60.00 HDTV 

1080i

12.

1920x1080 33.72 

59.94 

HDTV 

1080i

13.

1920x1080 56.250 

50 

HDTV 

1080p

14.

1920x1080

67.5 60 

HDTV 

1080p

- 8 -

No

Specification

Proposed

Remark

Resolution

H-freq(kHz)

V-freq(Hz)

Pixel Clock(MHz)

1.

720*400 

31.468 

70.08

28.321 

For only DOS mode

2.

640*480 31.469 

59.94

25.17  VESA

Input 848*480 60Hz, 852*480 60Hz

-> 640*480 60Hz Display

3.

800*600

37.879

60.31

40.00 VESA 

4.

1024*768 48.363 60.00

65.00 VESA(XGA) 

5.

1280*768 47.78 59.87

79.5 

WXGA 

 

6.

1360*768 47.72

59.8

84.75 

WXGA

7.

1366*768 47.56

59.6

84.75 

WXGA 

8.

1280*1024 63.595  60.0 

108.875

SXGA

FHD 

model 

9.

1600*1200

74.07 59.98 

130.375

UXGA

FHD 

model

10.

1280*720 45

60 

74.25  720P 

DTV 

Standard

11.

1920*1080 66.647 

59.988

138.625  WUXGA

FHD 

model

No

Resolution

H-freq(kHz)

V-freq.(Hz)

Pixel clock(MHz)

Proposed

Remark

1.

720*400 31.468 

70.08 

28.321 

HDCP

2.

640*480 31.469 

59.94 

25.17

VESA  HDCP

3. 800*600

37.879

60.31 

40.00 

VESA 

HDCP

4.

1024*768

48.363

60.00 65.00 

VESA(XGA)

HDCP

5.

1280*768 47.78

59.87

79.5

WXGA  HDCP

6.

1360*768 47.72 59.8 84.75

WXGA  HDCP

7.

1366*768 47.56

59.6

84.75 

WXGA  HDCP

8.

1280*1024 63.595

60.0  108.875  SXGA

HDCP

9.

1600*1200

74.07

59.98 130.375  UXGA 

HDCP

10.

1920*1080 66.647 59.988 

138.625  WUXGA

HDCP

No

Resolution

H-freq(kHz)

V-freq.(Hz)

Pixel clock(MHz)

Proposed

Remark

1.

720*480 

15.734 /15.6 

59.94 /60

27.00 

SDTV 480I

2.

720*480 

31.469 /31.5 

59.94 /60

27.00/27.03

SDTV 480P

3.

720*576 15.625 

50

27(54)

SDTV 

576I

4.

720*576 31.25 

50

54 

SDTV 

576P

5.

1280*720 37.500 

50

74.25 

HDTV 

720P

6.

1280*720 

44.96 /45 

59.94 /60

74.17/74.25 

HDTV 720P

7.

1920*1080 

33.72 /33.75 

59.94 /60

74.17/74.25 

HDTV 1080I

8.

1920*1080 28.125 50.00

74.25 

HDTV 

1080I

9.

1920*1080 

26.97 /27 

23.97 /24

74.17/74.25 

HDTV 1080P

10.

1920*1080

33.716 /33.75

29.976 /30.00

74.25

HDTV 1080P

11.

1920*1080 56.250 50

148.5

HDTV 

1080P

12.

1920*1080 

67.43 /67.5 

59.94 /60

148.35/148.50 

HDTV 1080P