LG LAC2900N, Service Manual

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2-5
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CAUTION - Tip for repair
Before exchange power amp IC(TB2946) for no audio problem, you have to check
below list.
1. Check VCC (pin 20,6) & GND
2. Check input pin 11,12,14,15
3. Check Standby, pin 4
: Follow the below list.
4. Check Mute function, pin 22
: Follow the below list.
5. Check Ripple pin 10.
: Normally it is high (about 10V)
6. Re-soldering all the pin of IC.
: Prevent crack of solder line.
* Keep changed IC, We request that you send it to HQ.
Stand-by Power Sound Voltage
ON OFF OFF 0 to 1.5
OFF ON ON 3.5 to 6V
Mute Sound Voltage
ON OFF 0 to 1.5
OFF ON 3.5 to 6V
R
L
R
L
R
L
11
9
8
7
5
2
3
17
18
19
21
24
23
12
15
14
1 20 6
R
L
IN1
IN2
IN3
IN4
13
C
1
C
1
C
1
C
1
PRE-GND
10 25 22
OUT1 +
+
+
+
-
-
-
-
( )
PW-GND1
OUT1 ( )
OUT2 ( )
PW-GND2
OUT2 ( )
OUT3 ( )
PW-GND3
OUT3 ( )
OUT4 ( )
PW-GND4
OUT4 ( )
TAB V
CC1
V
CC2
C
3
C
4
C
2
: PRE-GND
: PW-GND
STBY RIP MUTE
C
5
16
C
6
4
OFF-SET
DET
MUTE
PLAY
5 V
R
1
AC-GND
Picture 1) Power IC desc.