LG OM7550 - Page 40

3-19
ONE POINT REPAIR GUIDE
10. NO SOUND
There is no sound output in the USB function, repair the set according to the following guide.
10-1. USB FUNCTION
10-1-1. Solution
Replace IC501 on MAIN board, ICA201 on TOP board.
10-1-2. How to troubleshoot (Countermeasure)
1) Check +5 VU to USB board.
 if +5.6 VA to pin1 of ICA201(LDO) doesn’t come out, check pin8 & 9 of CN106.
 if +5.6 VA is normal & +5 VU of ICA201 pin2 doesn’t come out, then replace ICA201.
2) Check “Digital audio AMP block”.
10-1-3. Service hint (Any picture / Remark)
D
D+
D-
D-
(±5 V )
(±66.5 V)
DRIVER
IRS2092
OP AMP
AZ4580
FET
IRF6775
X2
DRIVER
IRS2092
OP AMP
AZ4580
FET
IRF6775
X2
MLC3730
Main DSP
(+3.3V_CD, VCC1.2)
USB1
USB2
IC201
ADC
CS5346
PRE, AMP
S4308
DAC
PCM5101
PS9860
PWM
DRM_WEN/CAS/
RAS/SEL/CLK/CKE
AMP_OSC
ADC_DATA
MCS_BCK/LRCK/MCLK
FRONT(SE)
SW(SE)
IR_IN_FL
FL_OUT_P/N
SW1_OUT_P/N
M00_15
A00_16
SF_DI/DO
SF_CS/SCK
500 W
MOT_MUTE,CLOSE,OPEN
D2S+/ -
IR_IN_SW
PWM_LRCK/BCK/DATA
DSP_O_DATA
AUX_DATA
EXP_DATA
MCS_BCK/LRCK, MCLK
C
CD_RW/MCLK/LRCK/BCK,
CD_DAT
CD_RST
UART_RX/TX
For AUX
For MIC
PGPC08
1.1 2.0
IC101
Micom
PCM1808
SCRATCH A/B,
M_VOL_A/B,
FAN_CTRL /2,
DJ Effect Scratch/Level
DRV632
DRIVER
IRS2092
OP AMP
AZ4580
FET
IRF6775
X2
SW(BTL)
IR_IN_SW
SW2_OUT_P/N
500 W
1000 W
SF_DI/DO
SF2_CS/SCK
AUX OUT
AUX IN
TUNER
(FM/AM)
PTB
MIC 1
MIC 2
BT_TX/RX
BT_PCM_BUFFER
D1+/-
USB D+/D- (CN502 pin5, 6 & 8, 9)
< Waveform of USB D± signal >
< USB function signal fl ow >