LG CK57 Service Manual page 50

NO SOUND
There is no sound output in the USB FUNCTION, repair the set according to the following guide.
5-3. IN THE USB FUNCTION
5-3-1. Solution
Please check and replace IC500 and IC104 on MAIN board.
5-3-2. How to troubleshoot (Countermeasure)
1) Check +USB_5V to Front USB board.
2) Check USB D1± or USB D2± from MAIN board to Front USB board.
a. Check 2.0_D1±signals(pin U7, U8 ) or 1.1_D1± signals(pin A7, A8 ) to IC500.
b. Check USB± signals to CN502(pin1, 2, 4, 5).
3) If there is any trouble, check the power for each IC. The power is normal but , if the signal waveform to
the IC is distorted or no signal, replace it with a new one.
5-3-3. Service hint (Any picture / Remark)
A, B, C , D , E, F, PD
( VC C 50)
LD
P/ U P
SPD O / SLD O
/ FO D / TR D
M
LO AD ± , SLED ± ,
SPI N ± , TR ± , F±
D EC K
O P_SW , C L_SW , U P_SW , D N _SW , D _SEN SE
M EC H AN I SM
M D
Bl ock
< USB function signal fl ow >
ONE POINT REPAIR GUIDE
2. 0 1. 1
U SB2
U SB1
C D _R ST
SER VO
I C 401
( 4 X)
C D _R W / M C LK/ LR C K/ BC K,
C D _D AT
D 1+/ -
M O T_M U TE, C LO SE, O PEN
I C 400
M ot or D r i ve
D 2S+/ -
( +3. 3V_C D , VC C 1. 2)
I I C 501
M ai n D SP
LPF
FR O N T( BTL)
PW M
AM P
I C 700
I C 702
FR O N T( BTL)
CK57 Only
LPF
SW(PBTL)
AM P
I c701
PW M + AM P Bl ock
[CK57 : Total 2.1ch 1100W
350+350+400]
[CK56 : Total 2ch 700W]
D- to pin 1&4 of CN502
D+ to pin 2&5 of CN502
< Waveform of USB D± signal >
3-13
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