LG 50PC52-ZD (CHASSIS:PP78A) Service Manual ▷ View online
- 21 -
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
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
- 22 -
15. HDMI mode
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
- 23 -
BLOCK DIAGRAM
SIDE_Y/C
PC_Audio
RF
PC_Audio_L/R
TUNER
TV_V
S I F
AV_RCA
MNT_OUT MNT_OUT
COMP1
COMP2
COMP_Y/Pb/Pr
TDA3107D2 TDA3107D2
AmpAmp
Tx0/1/2/3/4/C
12V Panel /DISP_EN
R_SPK_OUT
#1 RX 0/1/2/CLK
DDC_SCL/SDA1/2
HDMI
(PC/DTV)
SCART1
SCART2
SCARTSCART
RGBRGB
COMP1_Y/Pb/Pr
TV_OUT TV_OUT
SCART1,2_R/L
R/L_Audio
(Analog_out)
RGB
(PC/DTV)
PC_RGB
A V S-A V
SIDE_V
PC_SCL/SDA
I
2
C
L_SPK_OUT
RT-OPTION
RGB_HS/VS
HDMI_HS/VS
30P_LVDS
HEAD_OUT
L/R
HEAD_OUTHEAD_OUT
L/R L/R
COMP2_R/L
HS/VS
PIP OPTION
ANX9021ANX9021
(TMDS RECIEVER)(TMDS RECIEVER)
TEA6420TEA6420
Sound switch Sound switch
#2 RX 0/1/2/CLK
SIDE_R/L
SCART1,2_V (RCA1,2_V)
EEPROMEEPROM
SUB-TUNER
VIDEO_DECODERVIDEO_DECODER
TW9909TW9909
EEPROMEEPROM
VCT-ProVCT-Pro
(Lip-sync)(Lip-sync)
SCART_FB
AV_AUDIO R/L
AM_AUDIO
COMP1_R/L
I
2
C
RX 0/1/2/CLK
TV_OUTTV_OUT
MNT_OUTMNT_OUT
PIP_VPIP_V
ITU-656_IN
SCART1,2_I D
HDMI_Y/
Pb
/Pr(1080P
)
SCART_RGB
STMAV335
(MUX)
RT- OPTION
COMP1_R/L
RCA1,2_V(OPTION)
COMP2_Y/Pb/Pr
(OPTION)
COMP2_R/L
MC74HC4066MC74HC4066
DOWNLOAD_SW
I
2
C
I
2
C
I
2
C
COMP1_Y/Pb/PrCOMP1_Y/Pb/Pr
COMP2_Y/Pb/PrCOMP2_Y/Pb/Pr
(OPTION)(OPTION)
74ACT25374ACT253
(MUX)(MUX)
TV_SUBTV_SUB
- 24 -
EXPLODED VIEW
300
306
600
400
900
501
590
520
502
303
207
302
101
301
570
204
250
208
203
580
205
200
560
120
202
304
201
240
901
206
603
601
602
A2
A21
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