LG 42PC51-ZB (CHASSIS:PP78A) Service Manual ▷ View online
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8. In the case of an unusual display in SCART 1 mode.
Is the video input
of the A/V jack normal?
(Check R172)
Yes
Sam as Block A
Check the input source.
No
9. In the case of an unusual display in SCART 1_RGB mode.
Is the
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 the case of an unusual display in SCART 2 mode.
Is the 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 the case of an unusual display in component 1 mode.
Is the video
input of the A/V jack
normal? (Check R248,
R249,R250)
Yes
Change the IC(IC500)
Check the input source.
No
12. In the case of an unusual display in component 2 mode.
Yes
Change the IC(IC500)
Check the input source.
No
Is the video
input of the A/V Jk202
normal? (Check R241,
R242, R243)
13. In the case of an unusual display in RGB mode.
Yes
Change the IC(IC500)
Check the input source.
No
Is the
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) There is a picture but no sound.
2) There is a picture but no sound.
(2) Follow check
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Is there sound in any
mode?
Is the speaker
on?
Yes
Yes
Is the speaker
cable normal?
cable normal?
Yes
Yes
Is there no sound
only for HDMI?
Yes
Is there no
sound only AV
/COM2/PC?
Is the output
of IC600(R607, R608)
normal?
Yes
Is there no sound
only for RF?
No
No
No
No
Download the EDID data.
Set speaker on
in the menu.
in the menu.
No
Replace the
IC600
No
Check the Speaker
cable
cable
No
Is the IC500
operating normal?
Replace the IC500
No
Yes
Is the IC601
operating normal?
Replace the IC601
Replace the VSC BD
Yes
Check the signal after IC600.
refer to circuit diagram.
refer to circuit diagram.
Check the Tuner In/Out.
No
15. HDMI mode
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Is only video
normal?
Is only audio
normal?
No
Yes
Download EDID data each port.
Check the TMDS line wave.
(R312~E3273)
(R312~E3273)
1. Check the HDMI receiver’s status register. (0x60, offset 0x66)
- If the value is 0xf or 0x8, it is normal.
2. Check the HDCP register. (0x6, offset 0x32)
- Enable bit 6 : HDCP key loaded
- Enable bit 5 : HDCP decryption active
- Enable bit 4 : HDCP authentication attempted
- Enable bit 5 : HDCP decryption active
- Enable bit 4 : HDCP authentication attempted
Reset TMDS power down/ on register.
- 0x60, offset 0x3f => 0xff
- 0x60, offset 0x3f => 0xff
Check HDMI source.
Change to another source or cable.
Change to another source or cable.
Yes
Is the wave
continuous?
Normal video,
Normal audio?
No
Yes
Replace the 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. Unplug and plug in the HDMI cable.
(sometimes ESD surge occurred at HDMI port.)
3. Check the HDMI Mute register. (0x68, offset 0x37)
4. Check the Audio-out channel mute register (0x68,
4. Check the Audio-out channel mute register (0x68,
offset 0x32) is appropriately enabled.
Yes
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