LG 42LT760H-SA (CHASSIS:LJ3AZ) 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 cir-
cuit 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 pos-
sible 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 connec-
tions).
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 con-
nected 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.
1. Application range
This spec sheet is applied to the LED TV used LJ3AZ chassis
2. Test condition
Each part is tested as below without special notice.
1) Temperature : 25 ºC ± 5 ºC, CST : 40 ºC±5 ºC
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 20 minutes prior to
the adjustment.
3. Test method
1) Performance: LGE TV test method followed
2) Demanded other specification
- Safety : CE, IEC specification
- EMC: CE, IEC
4. General Specification
No
Item
Specification
Measurement
Remark
1.
Display Screen Device
32 wide Color Display Module
32”
Edge LED
42 wide Color Display Module
42”
2.
Aspect Ratio
16:9
3
LCD Module
32” TFT LCD Slim Edge LED HD 50Hz (LC320EXN-SEA2)
32” : LGD (HD)
42” : LGD (FHD)
42” TFT LCD Slim Edge LED FHD 50Hz (LC420EUE-SEM1)
4
Operating Environment
Temp. : 0 ~ 50 deg
Humidity : 20 ~ 90 %
5.
Storage Environment
Temp. : -20 ~ 60 deg
Humidity : 10 ~ 90 %
6.
Input Voltage
AC100 ~ 240V, 50/60Hz
7.
Power Consumption
(power On : white)
32” Module
Typ. 45[W] 80[W] Max.
42” Module
Typ. 89[W] 100[W] Max.
Pixel Pitch
32” Module
170.25 um x 510.75 um x RGB
42” Module
0.4845 mm x 0.4845 mm
- 7 -
5. RGB Input (PC)
No
Resolution
H-freq(kHz)
V-freq.(kHz)
Pixel clock
Proposed
Remarks
1.
720*400
31.469
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
54.348
60.053
74.00
VESA
6
1360*768
47.712
60.015
84.75
WXGA
7
1280*1024
63.981
60.02
108.875
SXGA
FHD model
8
1920*1080
66.587
59.93
138.625
WUXGA
FHD model
6. HDMI input
6.1. DTV mode
No
Resolution
H-freq(kHz)
V-freq.(kHz)
Pixel clock
Proposed
Remarks
1.
720*480
31.469/31.50
59.94/60
27.00/27.03
SDTV 480P
2.
720*576
31.25
50
54
SDTV 576P
3
1280*720
37.500
50
74.25
HDTV 720P
4
1280*720
44.96/45
59.94/60
74.17/74.25
HDTV 720P
5
1920*1080
33.72/33.75
59.94/60
74.17/74.25
HDTV 1080I
6
1920*1080
28.125
50.00
74.25
HDTV 1080I
7
1920*1080
26.97/27
23.97/24
74.17/74.25
HDTV 1080P
FHD model
8
1920*1080
33.716/33.75
29.976 / 30.00
74.25
HDTV 1080P
FHD model
9
1920*1080
56.250
50
148.5
HDTV 1080P
FHD model
10
1920*1080
67.43/67.5
59.94/60
148.35/148.50
HDTV 1080P
FHD model
No
Resolution
H-freq(kHz)
V-freq.(kHz)
Pixel clock
Proposed
Remarks
1.
720*400
31.469
70.08
28.321
DOS
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
74.12
VESA
HDCP
6
1360*768
47.712
60.015
84.75
WXGA
HDCP
7
1280*1024
63.981
60.020
108.875
SXGA
HDCP / FHD model
8
1920*1080
67.5
60.00
138.625
WUXGA
HDCP / FHD model
6.2. PC mode
- 8 -
ADJUSTMENT INSTRUCTION
1. Application Range
This spec. sheet applies to LJ3AZ Chassis applied LED TV all
models manufactured in TV factory
2. Specification
(1) Because this is not a hot chassis, it is not necessary to use
an isolation transformer. However, the use of isolation
transformer will help protect test instrument
(2) Adjustment must be done in the correct order
(3) The adjustment must be performed in the circumstance of
25 ±5ºC of temperature and 65±10% of relative humidity if
there is no specific designation.
(4) The input voltage of the receiver must keep 100~240V,
50/60Hz.
(5) The receiver must be operated for about 5 minutes prior to
the adjustment when module is in the circumstance of over
15
▪ In case of keeping module is in the circumstance of 0°C, it
should be placed in the circumstance of above 15°C for 2
hours
▪ In case of keeping module is in the circumstance of below
-20°C, it should be placed in the circumstance of above 15°C
for 3 hours,
*Caution) When still image is displayed for a period of 20
minutes or longer (especially where W/B scale is
strong. Digital pattern 13ch and/or Cross hatch
pattern 09ch), there can some afterimage in the
black level area
3. Adjustment items
3.1. Main PCB Check Process
(1) MAC Address Download
(2) CI+ Key Download
(3) Adjust 1920*1080 RGB
(4) EDID downloads for HDMI and RGB-PC
● Remark
- Above adjustment items can be also performed in Final
Assembly if needed. Adjustment items in both PCBA and
final assembly stages can be checked by using the INSTART
Menu -> 1.ADJUST CHECK
3.2. Final Assembly adjustment
(1) White Balance adjustment
(2) Adjust ADC (OPT)
(3) RS-232C functionality check
(4) PING Test
(5) Factory Option setting per destination
(6) Ship-out mode setting (IN-STOP)
(7) GND and HI-POT test
3.3. Appendix
(1) Tool option menu, USB Download (S/W Update, Option and
Service only)
(2) Manual adjustment for ADC calibration and White balance.
(3) Shipment conditions, Channel pre-set
4. MAIN PCBA Adjustments
4.1. ADC Calibration
4.1.1. Overview
ADC adjustment is needed to find the optimum black level and
gain in Analog-to-Digital device and to compensate RGB
deviation
4.1.2. Equipment & Condition
1) USB to RS-232C Jig
2) MSPG-925 Series Pattern Generator(MSPG-925FA, pattern
-65)
- Resolution : 1080P Comp1
1920*1080P RGB
- Pattern : Horizontal 100% Color Bar Pattern
- Pattern level : 0.7±0.1 Vp-p
- Image
4.1.3. Adjustment method
▪ Don’t need to adjust ADC because there is data in OTP and
adjusted initially
4.2. MAC Address D/L and CI+ D/L (Widevine
and ESN : Spec Out)
4.2.1. Equipment & Condition
1) Play file: keydownload.exe
4.2.2. Communication Port connection
1) Key Write: Com 1,2,3,4 and 115200 (Baudrate)
2) Barcode: Com 1,2,3,4 and 9600 (Baudrate)
4.2.3. Download process
1) Select the download items.
2) Mode check: Online Only
3) Check the test process
- DETECT -> MAC -> CI+
4) Play: START
5) Check of result: Ready, Test, OK or NG
6) Printer Out (MAC Address Label)
4.2.4. Communication Port connection
1) Connect: PCBA Jig->RS-232C Port == PC->RS-232C Port
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