LG 42LA790V / 42LA790W (CHASSIS:LD34D) Service Manual ▷ View online
69 / 90
Entry method
1. Press the IN-START button of the remote controller for adjustment
2. Check the entry into adjustment item 3
Standard Repair Process Detail Technical Manual
POWER OFF MODE checking method
B. Power error
_Off when on, off whiling viewing
<ALL MODELS>
A22
Established
date
Revised
date
Error
symptom
Content
LCD TV
2012. 12 .06
70 / 90
Checking method
1. Press the MENU button on the remote controller
2. Select the SOUND function of the Menu
3. Change TV Sound Out to TV Speaker
Standard Repair Process Detail Technical Manual
Checking method in menu when there is no audio
C. Audio error_No audio/Normal video
<ALL MODELS>
A24
Established
date
Revised
date
Error
symptom
Content
LCD TV
2012. 12 .06
71 / 90
24 Pin
(Power Board ↔ Main Board)
SMAW200-H24S
1
Power on
2
Inverter On/off
3
3.5V
4
PWM Dim #1
5
3.5V
6
PWM Dim #2
7
GND
8
GND
9
24V
10
24V
11
GND
12
GND
13
12V
14
12V
15
12V
16
24V
17
GND
18
GND
19
GND
20
GND
21
GND
22
L/DIMO_VS
23
L/DIM0_MOSI
24
L/DIM0_SCLK
Checking order when there is no audio
①
Check the contact condition of or 24V connector of Main Board
②
Measure the 24V input voltage supplied from Power Board
(If there is no input voltage, remove and check the connector)
③
Connect the tester RX1 to the speaker terminal and if you hear the Chik Chik sound when you touch the GND
and output terminal, the speaker is normal.
Standard Repair Process Detail Technical Manual
Voltage and speaker checking method
when there is no audio
when there is no audio
C. Audio error_No audio/Normal video
<ALL MODELS>
A25
Established
date
Revised
date
Error
symptom
Content
LCD TV
②
2012. 12 .06
②
①
③
72 / 90
Checking order
1, 2. Check IR cable condition between IR & Main board.
3. Check the st-by 3.5V on the terminal 4.
4. When checking the Pre-Amp when the power is in ON condition, it is normal when the Analog
Tester needle moves slowly, and defective when it does not move at all.
Standard Repair Process Detail Technical Manual
Remote controller operation checking method
D. Function error_ No response in remote controller,
key error
key error
<ALL MODELS>
A27
Established
date
Revised
date
Error
symptom
Content
LCD TV
P4101
1
GND
2
KEY1
3
KEY2
4
+3.5V_ST
5
GND
6
LOGO/LED_R
7
IR
8
GND
①
②
③
④
2012. 12 .06
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