LG 42LC7R (CHASSIS:LP78A) Service Manual ▷ View online
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8. In case of becomes unusual display from SCART 1 mode.
Is video input
of the A/V jack normal?
(Check R172)
Yes
Sam as Block A
Check the input source.
No
9. In case of becomes unusual display from SCART 1_RGB mode.
Is
video input of
the A/V jack normal?(Check
R110,R170, R171,
R173)
Yes
Sam as Block A
Check the input source.
No
10. In case of becomes unusual display from SCART 2 mode.
Is video input of
the A/V jack normal?
(Check R174)
Yes
Sam as Block A
Check the input source.
No
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11. In case of becomes unusual display from component 1 mode.
Is video
input of the A/V jack
normal? (Check R248,
R249,R250)
Yes
Change IC(IC500)
Check the input source.
No
12. In case of becomes unusual display from component 2 mode.
Yes
Change IC(IC500)
Check the input source.
No
Is video
input of the A/V jack
normal? (Check R241,
R242, R243)
13. In case of becomes unusual display from RGB mode.
Yes
Change IC(IC500)
Check the input source.
No
Is
R, G, B input
and H, V sync of the
JK201 normal?(Check R220,
R221, R253, R254,
R255)
14. No Sound
(1) Symptom
1) LED is green.
2) Screen display but sound is not output.
2) Screen display but sound is not output.
(2) Check following
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All input(mode)
is no sound.
Is the speaker
on it men?
Yes
Yes
Is the speaker
cable normal?
cable normal?
Yes
Yes
Only HDMI is
no sound.
Yes
Only AV
/COM2/PC input is
no sound.
Is the output
of IC600(R607, R608)
normal?
Yes
Only RF is no sound.
No
No
No
No
Download the EDID data.
Set on speaker
in menu.
in menu.
No
Replace IC600
No
Check the Speaker
cable
cable
No
IC500 operae
nor mall?
Replace IC500
No
Yes
IC601 operae
nor mall?
Replace IC601
Replace VSC BD
Yes
Check the signal after
IC600 refer to circuit
diagrma.
IC600 refer to circuit
diagrma.
Check the Tuner In/Out.
No
15. HDMI mode
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In only video
normal?
In only audio
normal?
No
Yes
Download EDID data each port.
Check TMDS line wave.
(R312~E3273)
(R312~E3273)
1. Check HDMI receiver’s status register. (0x60, offset 0x66)
- If the value is 0xf or 0x8, it is normal.
2. Check HDCP register. (0x6, offset 0x32)
- Enable bit 6 : HDCP key loaded
- Enable bit 5 : HDCP decryption active
- Enable bit 4 : HDCP authen. attempted
- Enable bit 5 : HDCP decryption active
- Enable bit 4 : HDCP authen. attempted
Reset TMDS power down/ on register.
- 0x60, offset 0x3f => 0xff
- 0x60, offset 0x3f => 0xff
Check HDMI source.
Change another source or cable.
Change another source or cable.
Yes
Is wave
continuous?
Normal video,
Normal audio?
No
Yes
Replace IC303.
No
1. Check TV input mode.
(HDMI 1 port support HDMI and DVI.
So if you input DVI signal and PC audio from
phone jack, You can hear PC audio.)
So if you input DVI signal and PC audio from
phone jack, You can hear PC audio.)
2. Uuplug and plug HDMI cable.
(sometimes ESD surge occurred at HDMI
port.)
port.)
3. Check HDMI Mute registe. (0x68, offset 0x37)
4. Check Audio-out channel mute register (0x68,
4. Check Audio-out channel mute register (0x68,
offset 0x32) is appropriately enabled.
Yes
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