LG NS9550F Service Manual

3-16
ONE POINT REPAIR GUIDE
6. NO SOUND
There is no sound output in the USB FUNCTION, repair the set according to the following
guide.
6-1. IN THE USB FUNCTION
6-1-1. Solution
Please check and replace IC501 on MAIN board & IC300 on USB board.
6-1-2. How to troubleshoot (Countermeasure)
1) Check +5VU to USB board.
 If +5.6 VA to pin2 of IC300(LDO) doesn’t come out, check pin4, 5 of CN304.
 If +5.6 VA is normal & +5VU of IC300 pin3 doesn’t come out, then replace IC300.
2) Check if “Digital audio AMP block”.
6-1-3. Service hint (Any picture / Remark)
D+
D-
< Waveform of USB D± signal >
USB D+ / D- (CN502 Pin1, 2 & 9, 10)
< USB function signal fl ow >
LC78615ERF+ SERVO
USB_HUB_DP/DN
CS5346
MLC3730
MCS LOGIC
E
N
ADC_DATA
DAC_MCLK
/BCK/LRCK
PT_L/R
AUX_L/R
AUX
USB1
Portable
CD_DIN_DOUT
CD_R/W,
BUSY,CD_16 M,
SUBSYQ,
CD_RST
CD_MCK/BCK
/LRCK/DATA
TUNER_L/R
USB2
TUNER
TAS5548
PWM
FL
±
RL±
DRIVER
IRS2092
(x 4 EA)
Front : 470 W X 2 ea
Woofer : 460 W X 2 ea
Front1 : 470 W X 2 ea
16.9344 MHz
C
S/MCU_RST
X
/RX
MIC_O_DATA0
(+3.3 V)
(+3.3 V_CD, VCC 1.2)
(+3.3 V_USB)
(+5 V,
+3.3 V_ADC)
(+3.3 V)
12.288 MHz
FR
±
RR±
SW
DAC IC
AZ4580
DAC IC
AZ4580
DAC IC
AZ4580
FL
RL
FR
RR
SW
FET
IRF6775
(x 12EA)
FL
RL
FR
RR
SW1
SW2
FL
RL
SW1
SW2
I2C/EXT_MUTE/RST
PWM_MCK/BCK/
LRCK
SPENA
AGL_F/R
AGL_SW
PROTEC /
SD/DCP
OTW
TH
FAN_CTL
AMP_OSC
MCS Interface
CLK/DAT/CE/RST/GPO2
S4308
MIC
MIC_SIG0
MIC_SIG
(+5_MIC)
MIC_DET
MIC CODEC
ADC CODEC
BT
BT_RX, BT_CTS
24 MHz
FL1
FL2

LG NS9550F Specifications

General

Brand	LG
Model	NS9550F
Category	Stereo System
Language	English