LG MAX221UB Service Manual

2-6
CAUTION - Tip for repair
Before exchange power amp IC(TB2931) 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 10 V)
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 1.0
OFF ON ON 2.2 to VCC
Mute Sound Voltage
ON OFF 0 to 1.0
OFF ON 2.2 to VCC
Picture 1) Power IC desc.
5 V
110 6 20
V
CC1
V
CC2
TABRipple
C2
+B
C3
C5
9
Out1 (+)
11
C1
8
7
PW-GND1
Out1 (−)
IN1
5
Out2 (+)
12
C1
2
3
PW-GND2
Out2 (−)
IN2
17
Out3 (+)
15
18
19
PW-GND3
Out3 (−)
IN3
21
Out4 (+)
14
C1
24
23
PW-GND4
Out4 (−)
IN4
13
16
C1
C6
4
Stby
25
22
Mute
C4
R1
Play
Mute
R
L
R
L
R
L
R
L
Pre-GND
AC-GND
Offset/short

LG MAX221UB Specifications

General

Brand	LG
Model	MAX221UB
Category	Receiver
Language	English