LG 42LH50 (CHASSIS:LA91L) Service Manual ▷ View online
- 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.
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
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.
melts.
2. Draw away the melted solder with an anti-static suction-type
solder removal device (or with solder braid) before removing the
IC.
IC.
Replacement
1. Carefully insert the replacement IC in the circuit board.
2. Carefully bend each IC lead against the circuit foil pad and
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
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
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.
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
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.
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
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.
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.
necessary, apply additional solder.
Fuse and Conventional Resistor
Removal/Replacement
1. Clip each fuse or resistor lead at top of the circuit board hollow
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.
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.
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).
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.
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.
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.
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.
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.
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 -
SPECIFICATION
NOTE : Specifications and others are subject to change without notice for improvement.
4. Electrical specification
4.1 General Specification
1. Application range
This specification is applied to the LCD TV used LA91L
chassis.
chassis.
2. Requirement for Test
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)
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.
accordance with BOM.
5) The receiver must be operated for about 5 minutes prior to
the adjustment.
3. Test method
1) Performance: LGE TV test method followed
2) Demanded other specification
2) Demanded other specification
- Safety: UL, CSA, IEC specification, CE
- EMC: FCC, ICES, IEC specification, CE
- EMC: FCC, ICES, IEC specification, CE
4.2 EyeQ-Green Motion Characters.
Ambient
Calculative Sensor
Backlight UI
Contrast
Brightness
Sharpness
Color
Illumination Illumination
500 300 100 100 50 70
70
300
180 55
90
50
62
50
200 120 25 90 50 58
54
50 42 0 90
50 52
65
No
Item
Specification
Remark
1. Receiving System
1) ATSC / NTSC-M
2. Available Channel
1) VHF : 02~13
2) UHF : 14~69
3) DTV : 02-69
4) CATV : 01~135
5) CADTV : 01~135
2) UHF : 14~69
3) DTV : 02-69
4) CATV : 01~135
5) CADTV : 01~135
3. Input Voltage
1) AC 100 ~ 240V 60Hz
Mark : 110V, 60Hz
4. Market
NORTH AMERICA
5. Screen Size
47 inch Wide(1920 ◊ 1080)
42 inch Wide(1920 ◊ 1080)
42 inch Wide(1920 ◊ 1080)
FHD
FHD
FHD
47LH50-UC
42LH50-UC
42LH50-UC
6. Aspect Ratio
16:9
7. Tuning System
FS
LC470WUF-SBB1
LGD(V4)
47LH50-UC
8. Module
LC420WUF-SBB1
42LH50-UC
9. Operating Environment
1) Temp : 0 ~ 40 deg
2) Humidity : ~ 80 %
2) Humidity : ~ 80 %
10. Storage Environment
1) Temp : -20 ~ 60 deg
2) Humidity : ~ 85 %
2) Humidity : ~ 85 %
- 7 -
5. Chroma& Brightness
No
Item
Min
Typ
Max
Unit
Remark
module 400 500
cd/m
1.
Max Luminance
(Center 1-point /Full White
pattern)
pattern)
set
400
77
500 cd/m
2.
Luminance uniformity
%
Full
white
3.
0.638
4.
RED X
0.334
5.
0.290
6.
GREEN
0.606
7.
0.144
8.
BLUE
0.064
9.
0.279
10.
Color
coordinate
coordinate
WHITE
Y
Y
X
Y
X
X
Y
Typ.
-0.03
0.292
Typ.
+0.03
11. Color coordinate uniformity
N/A
1000:1
1400:1
NORMAL
12. Contrast
ratio
8000:1
10000:1
DCR
Cool
0.281
0.274
0.283
0.311
0.276
0.283
0.283
0.278
0.285
0.285
Medium
0.291
0.285
0.293
0.293
0.287
0.295
0.295
3 Color
Temperature
Warm
0.327
0.313
0.329
0.329
0.315
0.331
0.331
No
Resolution
H-freq(kHz)
V-freq.(kHz)
Pixel clock
Proposed
1. 720*480
15.73
60
13.5135
SDTV
,DVD
480I
2. 720*480
15.73
59.94
13.5
SDTV
,DVD
480I
3. 720*480
31.50
60
27.027
SDTV
480P
4. 720*480
31.47
59.94
27.0
SDTV
480P
5. 1280*720
45.00
60.00
74.25
HDTV
720P
6. 1280*720
44.96
59.94
74.176
HDTV
720P
7. 1920*1080
33.75
60.00
74.25
HDTV
1080I
8. 1920*1080
33.72
59.94
74.176
HDTV
1080I
9. 1920*1080
67.500
60
148.50
HDTV
1080P
10. 1920*1080
67.432
59.94
148.352
HDTV
1080P
11. 1920*1080
27.000
24.000
74.25
HDTV
1080P
12. 1920*1080
26.97
23.976
74.176
HDTV
1080P
13. 1920*1080
33.75
30.000
74.25
HDTV
1080P
14. 1920*1080
33.71
29.97
74.176
HDTV
1080P
6. Component Video Input (Y, C
B
/P
B
, C
R
/P
R
)
- 8 -
7. RGB
8. HDMI Input (PC/DTV)
No
Resolution
H-freq (kHz)
V-fre q.(Hz)
Pixel clock(MHz)
Measu red
Result Proposed
PC
DDC
1. 640*350
31.468
70.09
25.17
31
Pass EGA
X
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
2. 720*400
31.469
70.08
28.32
40
Pass DOS
3. 640*480
31.469
59.94
25.17
35
Pass VESA(VGA)
4. 800*600
35.156
56.25
36.00
44
Pass VESA(SVGA)
5. 800*600
37.879
60.31
40.00
46
Pass VESA(SVGA)
6. 1024*768
48.363
47.776
47.712
63.981
75.00
66.587
47.776
47.712
63.981
75.00
66.587
60.00
58.870
60.015
60.020
60.00
59.934
58.870
60.015
60.020
60.00
59.934
65.00
79.5
85.50
108.00
162
138.5
79.5
85.50
108.00
162
138.5
60 Pass
VESA(XGA)
7. 1280*768
62
Pass VESA(XGA)
8. 1360*768
85
Pass CVT(WXGA)
9. 1280*1024
99
Pass VESA
(SXGA)
10. 1600*1200
120
Pass
VESA
(UXGA)
11. 1920*1080
126
Pass
HDTV
1080P
No
Resolution
H-freq(kHz)
V-freq.(Hz)
Pixel clock(MHz)
Proposed
PC
DDC
1 640*350
31.468
70.09
25.17
EGA
X
2 720*400
31.469
70.08
28.32
DOS
O
3 640*480
31.469
59.94
25.17
VESA(VGA)
O
4 800*600
35.156
56.25
36.00
VESA(SVGA)
O
5 800*600
37.879
60.31
40.00
VESA(SVGA)
O
6 1024*768
48.363
60.00
65.00
VESA(XGA)
O
7 1280*768
47.776
59.870
79.5
CVT(WXGA)
O
8 1360*768
47.712
60.015
85.50
VESA (WXGA)
O
9 1280*1024
63.981
60.020
108.00
VESA
(SXGA)
O
10 1600*1200
75.00
60.00
162
VESA
(UXGA)
O
11 1920*1080
67.5
60
148.5
HDTV
1080P
O
DTV
1 720*480
31.50
60
27.027
SDTV
480P
2 720*480
31.47
59.94
27.00
SDTV
480P
3 1280*720
45.00
60.00
74.25
HDTV
720P
4 1280*720
44.96
59.94
74.176
HDTV
720P
5 1920*1080
33.75
60.00
74.25
HDTV
1080I
6 1920*1080
33.72
59.94
74.176
HDTV
1080I
7 1920*1080
67.500
60
148.50
HDTV
1080P
8 1920*1080
67.432
59.939
148.352
HDTV
1080P
9 1920*1080
27.000
24.000
74.25
HDTV
1080P
10 1920*1080
26.97
23.976
74.176
HDTV
1080P
11 1920*1080
33.75
30.000
74.25
HDTV
1080P
12 1920*1080
33.71
29.97
74.176
HDTV
1080P
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