LG 42LG60 Manual page 73

LD1 Blue LED TFT Drive PWB Check
SET 0FF
LED OFF
Anode
Cathode
The appearance of LD1 when the set is on appears to be lit dimly.
However there is a small hole in the back panel frame and the
T-CON PWB that allows the backlight to make it appear lit.
P2 "SMPS" to P801 "Main PWB"
Odd Pins
Pin Label STBY Run
1 16V 0V 16V
3 Gnd Gnd Gnd
5 12V 0V 11.8V
7 Gnd Gnd Gnd
9 5V 5V 5.15V
11 5V 5V 5.15V
13 Gnd Gnd Gnd
15 Gnd Gnd Gnd
Left
17 ERR 3.19V 3.3V
Backlight 19 PWR 0V 2.86V
Plug 21 ADIM 0.1V 1.68V
23 SEL 0V 3.2V
PDIM Pin 22 can vary according to OSD Backlight
setting. 0.9V 0% to 3.3V 100%
P2
st
1 " short either pin 9, 10, 11 or 12 (5V) to Pin 19 (PWR) using a 10K resistor.
2 1
This turns on the power supply.
4 3
nd
2 : To test the Backlights, jump Pin 20 (INV) to Pin 19 (PWR)
6 5
Observe the Backlights.
8 7
If normal, the backlights should turn on and off 4 times. Then they go off.
10 9 If only ½ the backlights light, (Right side or Left Side), confirm connectors are OK.
If yes, panel defective.
12 11
If no backlight activity, confirm the Fuse F700 has approx. 300V on both sides.
14 13
If on one side, check fuse for open.
16 15 10K
If no 300V, replace Power Supply.
18 17
If 300V present, observe the center leg on the left hand side of ballast transformer
20 19
T701. Look for 45Khz pulse at 8.7V p/p.
22 21
If yes, confirm connectors to backlight OK, if OK, then panel defective.
24 23
If no pulse, replace the Power Supply.
Scope
Backlight pulse over
test point
1000V p/p (45KhZ)
POWER SUPPY
P402
F700
Ballast
5A 250V
Section
335V
P401
F700 90V in Stand-By
Side Control Keys
P100
42LG60 CIRCUIT INTERCONNECT DIAGRAM
BOOT OK SET ON
LED ON LED OFF
0V Anode 11.6V Anode 11.6V
CN5
0V Cathode 0V Cathode 9.5V
Pin Label STBY Run
2 16V 0V 16V
4 Gnd Gnd Gnd
6 12V 0V 11.8V
8 Gnd Gnd Gnd
Pins 17, 23 and 24
10 5V 5.15V 5.15V
Not Used
12 5V 5.15V 5.15V
Pin 21 is a
14 Gnd Gnd Gnd
Fixed Voltage
16 Gnd Gnd Gnd
18 ACD 4V 4.57V
20 INV 0V 3.29V
22 *PDIM 0V 3.38V
24 SYNC 0V 0V
IC108 IC109 IC110
IC108
5 (1.2V)
4 (1.3V)
3 (0V)
2 (3.37V)
1 (3.29V)
Pin 24
Pin 23
P2
Tweeter
Spk
F101
8A 250V
AC J3
AC In
TFT PANEL
US1
0V
1.8V
3.2V
CN4
5V Switching Regulator
U15 LD1
Function
UC1
In from IC806
On/Off
U16
Out (+5V-TU)
TFT-Drive (T-CON)
n/c
Gnd
CN1 CN2
F1
9V Regulator
3A 125V Function
In (+12V)
11.6V
Gnd
Out
LVDS 3.3V Regulator
Function
Gnd
Out
In
P103 P104
X101
P101
20.25Mhz LVDS
IC103
IC101
IC102
P102
TRU-MOTION
IC109 IC110
5 (0V) 5 (2.5V)
4 (1.79V) 4 (0V)
3 (0V) 3 (0V)
2 (3.36V) 2 (3.3V)
1 (3.29V) 1 (3.37V)
Tweeter
Ft. PWB
Assy.
J1
Spk
LG
J2
TUNER
5V Pin 3
J1
Video Pin 16
Ft. TOUCH
Audio SIF Pin 14
LED/Push Sw
FRONT SIDE OF MAIN PWB
IC800 IC807 IC802 (On Back)
2.6V Switching Regulator A2.6V-BCM 3.3V Regulator
Pin Volts Function Pin Volts Name Function Pin
1 8.95V In 6,7,8,10 5V Gnd 1 0V
2 3.3V Out 1,2,3,4,5 2.6V Out 2
3 5.0V On/Off 17 Power Control In 3 5V
4 0.0V Use L801 left side to test output IC805 (On Back)
5 0.0V Use any top pin of IC807 to test input 3.3V Switching Regulator A3.3V-BCM
IC806 IC820 Function Pin
1.2V Switching Regulator A1.2V-BCM In 2 5V
Pin Volts Function Pin Volts Name Out 4
1 11.6V In 6,7,8,10 5V On/Off 1
2 0.0V Out 1,2,3,4,5 1.2V IC810 (On Back)
3 9V On/Off 17 Power Control 1.8V Switching Regulator +1.8V-NTP
IC404 Use L014 left side to test output Function Pin
In 3
Use any top pin of IC820 to test input
Pin Volts IC404 uP 3.3V Out 2
1 0V 3.3VST-MICOM Gnd 1
2 3.3V Function Pin Volts Name Q802 (On Back)
3 5V In 3 5V ST_+5V 5V Switch control to Q801
Out 2 3.3V Reset Function Pin
Gnd 1 0V Gnd In C ST-5V
Control B
Gnd E
Tuner Pin 16 SMTE Color bar In
MAIN PWB
P800
IC600
IC820
*Q901
*Q902
P801
LD803
*IC400
IC503
3.3V BCM
Reset
IC805
BCM
OK LED
IC701
IC500
IC402
*IC805
Pin 1 ~ 16
*IC802
X200 (54Mhz)
1 16
IC900
IC806
TUNER
*IC810
IC800
ATSC/QAM/
IC501
NTSC P501
BACK SIDE OF MAIN PWB
Q801 (On Back)
5V Switch
Volts Function Pin Volts
Source C ST-5V
3.3V Control B RL-ON (PWR)
Gnd E 0V
IC405 uP Reset (On Back)
Reset by Charge of C431
Volts Function Pin Volts
In 1 3.3VST-MICOM
3.3V (A3.3V-BCM) Gnd 2 0.0V
Power Control-3.3V Out 3 Low to High to B Q400
Q902 (On Back)
12V LVDS control to Q901
Volts Function Pin Volts
3.3V from IC802 Source C 12V
1.8V (+1.8V-NTP) Control B LVDS-Panel-Control
0V Gnd E 0V
Q901 (On Back)
12V LVDS On control to P900 Pins 1~4
Volts Function Pin Volts
Source 1, 3 12V
RL-ON (PWR) Control 2, 4 Low from Q902
0V Output 5~8 12V
Right
Backlight
Plug
See back side of page for Waveforms for
P900 using SMTE Color bar as the Input.
IC807
IC1201
P900
IC302 IC304
IC300
IC100 IC1200
BCM
IC202
IC303
IC301
IC404
24Mhz
X400
Q400
IC1000
E B
P200
uP
P401
Not Used
IC407
*IC405
*Grayed out components on the back