LG 37LD840 (CHASSIS:LJ03B) Service Manual ▷ View online
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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
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.
1. Application range
This specification is applied to the LCD TV used LJ03B/D/E/F chassis.
2. Requirement for Test
Each part is tested as below without special appointment.
1) Temperature
: 25 ºC ± 5 ºC (77 ºF ± 9 ºF), CST : 40 ºC ± 5 ºC
2) Relative Humidity : 65 % ± 10 %
3) Power Voltage
3) Power Voltage
: Standard input voltage (AC 100-240 V~ 50 / 60 Hz)
* Standard Voltage of each products is marked by models.
* 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. Test method
1) Performance: LGE TV test method followed
2) Demanded other specification
2) Demanded other specification
- Safety: CE, IEC specification
- EMC:CE, IEC
- EMC:CE, IEC
- 7 -
4. Chrominance & Luminance Specification
1) LJ03B
No Item Min
Typ
Max
Unit Remark
1. Max
Luminance
Module 400
500
cd/m
2
32/42/47/55LD650
(Center 1-point / Full White Pattern)
Set 400 500
cd/m
2
32/42/47/55LD650
2.
Luminance uniformity
77
%
Full white
3. Color
coordinate
RED
X
Typ.
0.642 Typ.
32LD650
-0.03 0.636
+0.03
42LD650
0.639 47LD650
(TBD) 55LD650
Y 0.334
0.335
0.334
(TBD)
GREEN X
0.292
0.291
0.290
(TBD)
Y 0.607
0.603
0.606
(TBD)
BLUE X
0.146
0.146
0.146
(TBD)
Y 0.056
0.061
0.058
(TBD)
WHITE
X
0.279
Y
0.292
4.
Color coordinate uniformity
N/A
5.
Contrast ratio
1000:1
1400:1
32LD650
NORMAL
1100:1 1500:1
42/55LD650
1200:1 1500:1
47LD650 DCR
50,000:1
70,000:1
6.
Color Temperature
Cool
0.267
0.269
0.271
<Test Condition>
0.271
0.273
0.275
85% Full white pattern
Standard
0.283
0.285
0.287
** The W/B Tolerance is
0.291
0.293
0.295
±0.015 Adjustment
Warm 0.311
0.313
0.315
0.327
0.329
0.331
7.
Color Distortion, DG
10.0
%
8.
Color Distortion, DP
10.0
deg
9.
Color S/N, AM/FM
43.0
dB
10.
Color Killer Sensitivity
-80
dBm
- 8 -
6. Component Video Input (Y, C
B/
P
B
, C
R
/P
R
)
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
27.00
SDTV 480P
5.
720*576
15.625
50*
13.5
SDTV 576I
6.
720*576
31.25
50*
13.5
SDTV 576P
7.
1280*720
37.5
50*
74.25
HDTV 720P
8.
1280*720
45.00
60.00
74.25
HDTV 720P
9.
1280*720
44.96
59.94
74.176
HDTV 720P
10.
1929*1080
28.125
50*
74.25
HDTV 1080I
11.
1920*1080
33.75
60.00
74.25
HDTV 1080I
12.
1920*1080
33.72
59.94
74.176
HDTV 1080I
13.
1920*1080
56.25
50*
148.5
HDTV 1080P
14.
1920*1080
67.50
60
148.50
HDTV 1080P
15.
1920*1080
67.432
59.94
148.352
HDTV 1080P
16.
1920*1080
27.00
24.00
74.25
HDTV 1080P
17.
1920*1080
26.97
23.976
74.176
HDTV 1080P
18.
1920*1080
33.75
30.00
74.25
HDTV 1080P
19.
1920*1080
33.71
29.97
74.176
HDTV 1080P
8. RGB Input (PC)
No Resolution
H-freq(kHz) V-freq.(kHz) Pixel
clock
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
37.879
60.31
40.00
VESA(SVGA)
O
5.
1024*768
48.363
60.00
65.00
VESA(XGA)
O
6.
1280*768
47.776
59.87
79.50
CVT(WXGA)
O
7. 1360*768
47.712
60.015
85.50
VESA(WXGA)
O
8.
1280*1024
63.981 60.020 108.00
VESA(SXGA)
O
9.
1600*1200
75.00
60.00
162
VESA(UXGA)
O
10.
1920*1080
67.50
60
148.5
HDTV 1080P
O
• RGB PC Monitor Range Limits
Min Vertical Freq - 56 Hz
Max Vertical Freq - 62 Hz
Min Horiz. Freq - 30 kHz
Max Horiz. Freq - 80 kHz
Pixel Clock - 170 MHz
Max Vertical Freq - 62 Hz
Min Horiz. Freq - 30 kHz
Max Horiz. Freq - 80 kHz
Pixel Clock - 170 MHz
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