DOWNLOAD LG 42LY99-ZC (CHASSIS:LD75C) Service Manual ↓ Size: 4.83 MB | Pages: 28 in PDF or view online for FREE

Model
42LY99-ZC (CHASSIS:LD75C)
Pages
28
Size
4.83 MB
Type
PDF
Document
Service Manual
Brand
Device
TV / LCD
File
42ly99-zc-chassis-ld75c.pdf
Date

LG 42LY99-ZC (CHASSIS:LD75C) 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.
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 -
SPECIFICATION
NOTE : Specifications and others are subject to change without notice for improvement.
2. MODEL Gereral  Specification
No
Item
Specification
Remark
1.
Market
UK, German, Italy, France, Sweden, Finland,
Analog only
Spain, Netherlands, Belgium, Luxemburg, Greece,
Denmark, Czech, Austria, 
Rumania, Poland,
Portugal, Norway, Rumania, Hungary, Bulgaria,
Croatia, Serbia, Swiss, Slovenia, Russia
2.
Broadcasting system
1)  PAL-BG / I /I’/DK
2)  SECAM L/L’
3)  DVB-T
3.
Receiving system
Analog : Upper Heterodyne
Digital : COFDM
4.
Scart Jack (2EA)
PAL, SECAM
Scart 2 Jack : MNT / DTV output
5.
Video Input (1EA)
PAL, SECAM, NTSC
4 System : PAL, SECAM, NTSC, PAL60
6.
S-Video Input (1EA)
PAL, SECAM, NTSC
4 System : PAL, SECAM, NTSC, PAL60
7.
Component Input (1EA)
Y/Cb/Cr, Y/Pb/Pr
8.
RGB Input (1EA)
RGB-PC
9.
HDMI Input (3 EA)
HDMI-DTV & SOUND
10.
Audio Input (3 EA)
PC Audio, Component, AV
L/R Input
1. General Specification (LCD MODULE)
No
Item
Specification
Remark
1. 
Display Screen Device
42inch Full-HD 100Hz(WCG)
LCD
2. Aspect 
Ratio
16:9
3. LCD 
Module
42LY99(LC420WU4-SLA2)
4. 
Operating Environment
1) Temp.   : 0 ~ 40 deg
2) Humidity : 10 ~ 90%
LGE SPEC
5. 
Storage Environment
3) Temp.   : -20 ~ 50 deg
4) Humidity : 10 ~ 90 %
6. 
Input Voltage
100 - 240V~, 50/60Hz
- 7 -
3. Chroma & Brightness (LCD Module)
4. Component Video Input (Y, P
B
, P
R
)
No
Resolution
H-freq(kHz)
V-freq(Hz)
Pixel clock(MHz)
Proposed
720*480
15.73
59.94
13.500
SDTV, DVD 480I(525I)
720*480
15.75
60.00
13.514
SDTV, DVD 480I(525I)
720*576
15.625
50.00
13.500
SDTV, DVD 576I(625I)
4 720*480
31.47
59.94
27.000
SDTV 
480P
5 720*480
31.50
60.00
27.027
SDTV 
480P
6 720*576
31.25
50.00
27.000
SDTV 
576P
7 1280*720
44.96
59.94
74.176
HDTV 
720P
8 1280*720
45.00
60.00
74.250
HDTV 
720P
9 1280*720
37.50
50.00
74.25
HDTV 
720P
10 1920*1080
33.72
59.94
74.176
HDTV 
1080I
11 1920*1080
33.75
60.00
74.250
HDTV 
1080I
12
1920*1080
28.125
50.00
74.250
HDTV 1080I
13
1920*1080
67.50
60.00
148.50
HDTV 1080P
No
Item
Min.
Typ.
Max
Unit
Remark
1
Viewing Angle<CR>10>
R/L
178
U/D
178
2.
White average brightness
400
500
-
cd/m
- 100IRE Full White Pattern (255 gray)
- Picture : Dynamic (Cool)
3.
Brightness uniformity
1.3
cd/m
- 100IRE Full White Pattern (255 gray)
- Picture : Dynamic (Cool)
4.
Color Coordinate
White
X
Typ
0.279
Typ
- 85IRE Full White Pattern (216 gray)
Y
-0.03
0.292
+0.03
- Picture : Dynamic (Cool)
Red
X
0.663
Y
0.324
Green
X
0.194
Y
0.659
Blue
X
0.141
Y
0.082
5.
Color coordinate uniformity
-0.03
Average
+0.03
- 85IRE Full White Pattern (216 gray)
- Picture : Dynamic (Cool)
6.
Contrast Ratio
CR with
7000 : 1
10000 :1
- Full white(100IRE)
at dark room
PWM-Dimming
- Full black(0IRE) pattern
CR without
7000 : 1
10000 :1
- Picture : Dynamic (Cool)
PWM-Dimming
- Input : TV/DTV/AV1,2,3/Comp/HDMI1,2
-> CR with PWM-Dimming
RGB/HDMI-PC 
-> CR without PWM-Dimming
- 8 -
5. RGB PC INPUT (PC)
No
Resolution
H-freq(kHz)
V-freq.(Hz)
Pixel clock(MHz)
Proposed
Remarks
1.
720*400
31.468
70.08
28.32
2.
640*480
31.469
59.94
25.17
VESA
848*480 60Hz, 852*480 60Hz
37.500
75.00
31.50
-> Display 640*480 60H 
3
800*600
37.879
60.31
40.00
VESA
46.875
75.00
49.50
4.
832*624
49.725
74.55
57.283
Macintosh
5
1024*768
48.363
60.00
65.00
VESA(XGA)
56.476
70.00
75.00
60.023
75.03
78.75
6
1280*768
47.693
59.99
80.125
WXGA
7
1360*768
47.649
59.94
84.625
WXGA
8
1366*768
47.649
59.94
84.625
WXGA
9
1280*1024
63.595
60.0
108.875
SXGA
10
1400*1050
65.160
60.0
122.50
SXGA
11
1920*1080
66.647
59.988
138.625
WUXGA
Reduced Blanking Timing
6. HDMI input (DTV)
No
Resolution
H-freq(kHz)
V-freq.(Hz)
Pixel clock(MHz)
Proposed
Remarks
1.
720*480
31.47
59.94
27.00
SDTV 480P(4:3)
PC mode -> Display 640*480
2.
720*480
31.50
60
27.027
SDTV 480P(4:3)
3.
640*480
31.469
59.94
25.175
SDTV 480P(4:3)
4.
640*480
31.469
60.00
25.20
SDTV 480P(4:3)
5.
720*480
31.47
59.94
27.000
SDTV 480P(16:9)
6.
720*480
31.50
60.00
27.027
SDTV 480P(16:9)
7.
720*576
31.25
50.00
27.000
SDTV 576P
8.
1280*720
37.50
50.00
74.176
HDTV 720P
9.
1280*720
44.96
59.94
74.176
HDTV 720P
PC mode ->
10.
1280*720
45.00
60.00
74.250
HDTV 720P
Display 1280*768 60Hz
11
1920*1080
33.72
59.94
74.176
HDTV 1080I
12
1920*1080
33.75
60.00
74.250
HDTV 1080I
13
1920*1080
28.125
50.00
74.250
HDTV 1080I 50Hz
14
1920*1080
27.000
24.00
74.250
HDTV 1080P 24Hz
15
1920*1080
56.250
50
148.500
HDTV 1080P 50Hz
16
1920*1080
67.433
59.94
148.352
HDTV 1080P
PC mode ->
17
1920*1080
67.500
60
148.500
HDTV 1080P
Display 1920*1080 60Hz
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