LG 42LA790V / 42LA790W (CHASSIS:LD34D) Service Manual ▷ View online
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4. Changed BOM
Changed Item
: Separate HDCP check box.
- HDCP 2.0 Tx
- HDCP 2.0 Rx
- HDCP 1.4 Rx
As-Was
Current
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Contents of LCD TV Standard Repair Process
No.
Error symptom (High category)
Error symptom (Mid category)
Page
Remarks
1
A. Video error
No video/Normal audio
37
2
No video/No audio
38
3
Tuning fail, Picture broken/ Freezing
39, 40
4
Color error
41
5
Vertical/Horizontal bar, residual image, light
spot, external device color error
spot, external device color error
42
6
B. Power error
No power
43
7
Off when on, off while viewing, power auto
on/off
on/off
44
8
C. Audio error
No audio/Normal video
45
9
Wrecked audio/discontinuation/noise
46
10
D. Function error
Remote control & Local switch checking
47
11
External device recognition error
48
12
E. Noise
Circuit noise, mechanical noise
49
13
F. Exterior error
Exterior defect
50
14
G. Network error
Exterior defect
51, 52
First of all, Check whether there is SVC Bulletin in GCSC System for these model.
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Contents of LCD TV Standard Repair Process Detail Technical Manual
No.
Error symptom
Content
Page
Remarks
1
A. Video error_ No video/Normal audio
Check LCD back light with naked eye
A1
2
LED driver B+ 24V measuring method
3
Check White Balance value
A4
4
Power Board voltage measuring method
A5
6
A. Video error_ No video/Video lag/stop
TUNER input signal strength checking method
A6
7
LCD-TV Version checking method
A7
9
A. Video error_Color error
LCD TV connection diagram
A8
10
Tuner Checking Part
A9
11
Check Link Cable (LVDS) reconnection
condition
condition
12
Adjustment Test pattern - ADJ Key
A12
13
A. Video error_Vertical/Horizontal bar,
residual image, light spot
residual image, light spot
LCD TV connection diagram
A8
14
Check Link Cable (LVDS) reconnection
condition
condition
15
Adjustment Test pattern - ADJ Key
A12
16
<Appendix>
Defected Type caused by T-Con/
Inverter/ Module
Defected Type caused by T-Con/
Inverter/ Module
Exchange T-Con Board (1)
A-1/5
17
Exchange T-Con Board (2)
A-2/5
18
Exchange LED driver Board (PSU)
A-3/5
55
” : driver board
Other : PSU
19
Exchange Module itself (1)
A-4/5
20
Exchange Module itself (2)
A-5/5
Continue to the next page
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Contents of LCD TV Standard Repair Process Detail Technical Manual
No.
Error symptom
Content
Page
Remarks
21
B. Power error_No power
Check front display LED
A17
22
Check power input Voltage & ST-BY 3.5V
A18
23
Checking method when power is ON
A19
24
POWER BOARD voltage measuring method
A5
25
26
B. Power error_Off when on, off while
viewing
viewing
POWER OFF MODE checking method
A22
27
B. Power error_Off when on, off while
viewing
viewing
POWER BOARD PIN voltage checking method
A19
28
C. Audio error_No audio/Normal video
Checking method in menu when there is no
audio
audio
A24
29
Voltage and speaker checking method when
there is no audio
there is no audio
A25
30
C. Audio error_Wrecked
audio/discontinuation
audio/discontinuation
Voltage and speaker checking method in
case of audio error
case of audio error
A25
31
D. Function error_ No response in
remote controller, key error
remote controller, key error
Remote controller operation checking method
A27
32
D. VCOM Adjustment
Sequence of the Vcom adjustment
A28
Continued from previous page
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