
3-12
Copyright © 2018 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
ONE POINT REPAIR GUIDE
NO SOUND
There is no sound output by DIGITAL AUDIO AMP DAMAGE, repair the set according to the following
guide.
5-2. BY DIGITAL AUDIO AMP DAMAGE (IN ALL FUNCTIONS)
5-2-1. Solution
Please check and replace IC701, IC702 on MAIN board.
5-2-2. How to troubleshoot (Countermeasure)
1) Check PWM_FL±, PWM_FR± & PWM_SW± signals from IC700 to IC701, IC702 each input function.
If no signal, check if I2S audio signals are entered to IC700.
Refer to “I2S audio signal interface” on Item 5-1.
2) Check PVDD.
If PVDD is abnormal, check the SMPS.
3) Check +12 V for driving the gate of AMP IC.
a. All the powers are normal, but if +12 V is low, there is possible for AMP IC to be damaged.
b. Remove L702, L703(FRONT), L701 and L704(WOOFER) one by one.
When removed a inductance, if +12 V is recovered, the IC connected to it was damaged.
c. Replace the IC with a new one.
4) Check the impedance between IC701/IC702_OUT_A/OUT_B/OUT_C/OUT_D & GND.
a. If the impedance is 0
Ω
, the IC must be damaged.
b. After removing the heat sink, replace it with a new one.
5-2-3. Service hint (Any picture / Remark)
< MAIN board top view >
IC702
IC702
L703
L703
OUT_A
OUT_A
OUT_A
OUT_A
OUT_D
OUT_D
OUT_D
OUT_D
OUT_B
OUT_B
OUT_B
OUT_B
OUT_C
OUT_C
OUT_C
OUT_C
L702
L702
L704
L704
L701
L701
IC701
IC701
Содержание CK57
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