DOWNLOAD LG 32LC7D (CHASSIS:LB73A) Service Manual ↓ Size: 6.76 MB | Pages: 40 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 -

This specification is applied to LB73A chassis.

Testing for standard of each part must be followed in below
condition.

(1) Temperature : 25°C±5°C(77±9°F)
(2) Humidity : 65%±10%
(3) Power : Standard input voltage (AC 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 20 minutes prior

to the adjustment.

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

Safety : CB Specification
EMC   : CISPR 13 Specification

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

No

Item

Specification

Remark

1.

Broadcasting system

PAL-B/G, DTV : DVB-T

2.

Available Channel

1) VHF : 0~5, 5A, 6~9, 9A,10~12

2) UHF : 20 ~ 75

3) CATV: 02 ~ 44 

4) DTV : 06 ~9, 9A, 10~12, 27 ~ 69

3.

Tuner IF

1) PAL  : 38.90MHz(Picture),          

34.40MHz(Sound)

2) DVB-T : 36.125MHz

4.

Input Voltage

AC 240 V, 50Hz

Maker : LGE

5.

LCD Module

26" : T260XW03 (1366x768)

Maker : AU Optronics Corp.

32" : LC320WX4SLD2 WXGA

Maker : LG Philips LCD

6.

Aspect ratio

16:9 (wide)

7.

Operating Temperature

0

40

deg

8.

Operating Humidity

85

%

9.

Storage Temperature

-20

60

deg

10.

Storage Humidity

85

%

- 7 -

No

Item

Min

Typ

Max

Unit

Remark

1.

White peak Brightness

350

450

cd/m

2

HDMI input(255level)

300

400

cd/m

2

RF/AV/COMP/RGB input

(255 level)

2.

Contrast Ratio

600 : 1

800 : 1

HDMI input

500 : 1

700 : 1

RF/AV/COMP/RGB input

3.

Brightness uniformity

1.3

Refer to LCD spec.

4.

Color coordinate

RED

X

0.635

± 0.03

Y

0.339

± 0.03

GREEN

X

0.282

± 0.03

Y

0.606

± 0.03

BLUE

X

0.145

± 0.03

Y

0.064

± 0.03

WHITE

X

0.279

± 0.03

Y

0.292

± 0.03

5.

Viewing Angle(H/V)

178/178

CR > 10

6.

Color Temperature

Cool

11,000

12,000

13,000

Warm

5,500

6,500

7,500

Medium

8,300

9,300

10,300

No

Resolution

H-freq(kHz)

V-freq.(kHz)

Pixel clock(MHz)

Remarks

1.

720*576

15.625

50.00

13.50

SDTV576i

2.

720*576

31.25

50.00

27.00

SDTV576p

3.

720*480

15.73/15.75

59.94/60.00

13.50

SDTV 480i

4.

720*480

31.47/31.50

59.94/60.00

27.00

SDTV 480p

5.

1280*720

44.96/45.00

59.94/60.00

74.25

HDTV 720P

6.

1280*720

37.50

50.00

74.25

HDTV 720P

7.

1920*1080

33.72/33.75

59.94/60.0

74.25

HDTV 1080i

8.

1920*1080

28.125

50.00

74.25

HDTV 1080i

No

Resolution

H-freq(kHz)

V-freq.(kHz)

Pixel clock(MHz)

Remarks

1. 720*400

31.468

70.08

28.321

2. 640*480

31.469

59.94

25.17

VESA(VGA)

3. 640*480

37.500

75.00

31.50

VESA(VGA)

4. 800*600

37.879

60.31

40.00

VESA(SVGA)

5. 800*600

46.875

75.00

49.50

VESA(SVGA)

6. 1024*768

48.363

60.00

65.00

VESA(XGA)

7. 1024*768

56.476

70.06

75.00

VESA(XGA)

8. 1024*768

60.023

75.02

78.75

VESA(XGA)

9. 1280*768

47.776

59.870

79.5

CVT(WXGA)

10. 1360*768

47.720

59.799

84.750

CVT(WXGA)

11. 1366*768

47.13

59.65

72.00

12. 1920*1080

67.50

60.00

148.50

- 8 -

No

Resolution

H-freq(kHz)

V-freq.(kHz)

Pixel clock(MHz)

Remarks

DTV

1. 720*576

31.25

50.00

27.00

SDTV 

576p

2. 720*480

31.47/31.50

59.94/60.00

27.00

SDTV 

480p

3. 1280*720

44.96/45.00

59.94/60.00

74.25

HDTV 

720P

4. 1280*720

37.50

50.00

74.25

HDTV 

720P

5. 1920*1080

33.72/33.75

59.94/60.0

74.25

HDTV 

1080i

6. 1920*1080

28.125

50.00

74.25

HDTV 

1080i

7. 1920*1080

67.432/67.500

59.939/60

148.5

HDTV 

1080P

8. 1920*1080

56.25

50

148.5

HDTV 

1080P

9. 1920*1080

26.97/27.000

23.97/24.000

74.25

HDTV 

1080P

10. 1920*1080

33.71/33.75

29.97/30.000

74.25

HDTV 

1080P

PC

11. 720*400 

31.468

70.08

28.321

12.

640*480

31.469

59.94

25.17

VESAVGA)

13. 640*480

37.500

75.00

31.50

VESA(VGA)

14. 800*600

37.879

60.31

40.00

VESA(SVGA)

15. 800*600

46.875

75.00

49.50

VESA(SVGA)

16. 1024*768

48.363

60.00

65.00

VESA(XGA)

17. 1024*768

56.476

70.06

75.00

VESA(XGA)

18. 1024*768

60.023

75.02

78.75

VESA(XGA)

19. 1280*768

47.776

59.870

79.5

CVT(WXGA)

20. 1360*768

47.720

59.799

84.750

CVT(WXGA)

21. 1366*768

47.13

59.65

72.00

22. 1920*1080

67.50

60.00

148.50