LG LAC2900N Service Manual page 12

■ 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.
Stand-by Power
ON OFF
OFF ON
5. Check Ripple pin 10.
: Normally it is high (about 10V)
Mute Sound
ON OFF
OFF ON
6. Re-soldering all the pin of IC.
: Prevent crack of solder line.
* Keep changed IC, We request that you send it to HQ.
Sound Voltage
OFF 0 to 1.5
ON 3.5 to 6V
Voltage
0 to 1.5
3.5 to 6V
IN1
11
C
1
IN2
12
C
1
AC-GND
16
C
6
IN3
15
C
1
IN4
14
C
1
PRE-GND
13
Picture 1) Power IC desc.
2-5
1 20 6
TAB V V
CC1 CC2
OUT1 + ( )
9
PW-GND1 8
OUT1 ( )
-
7
OUT2 ( ) +
5
PW-GND2 2
OUT2 ( ) -
3
OUT3 ( )
+
17
PW-GND3 18
OUT3 ( ) -
19
OUT4 ( ) +
21
PW-GND4 24
OUT4 ( ) -
23
OFF-SET
RIP STBY MUTE
DET
10 4 25 22
R
1
R
L
R
L
R
L
R
L
5 V
PLAY
MUTE
: PRE-GND
: PW-GND