LG 42LH20 Service Manual page 70

P201 Odd "SMPS" to P700 "Main PWB" P201 Even "SMPS" to P700 "Main PWB"
Pin Label
Pin Label STBY Run Diode Check
24
*PWM-DIM
23 n/c n/c n/c n/c
22
Err Out
21 A.DIM 0V 1.7V Open
20
n/c INV-On/Off
19 n/c n/c n/c
0V 21.4V 18
17 24V 0.71V 24V
16 Gnd
Gnd Gnd Gnd Gnd
15
13 12V 0V 12.3V 0.96V 14 12V
12
11 Gnd Gnd Gnd Gnd Gnd
1.67 V 10
9 STBY 5V 5.1V 5.14V STBY 5V
STBY 5V 5.1V 5.14V 1.67 V 8
7 STBY 5V
6 Gnd
5 Gnd Gnd Gnd Gnd
3 Gnd Gnd Gnd Gnd 4 Gnd
1 n/c n/c n/c n/c 2 PWR_ON
Power Supply
3.15A / 250V Rating
Right Side
335V Actual Reading
From Rear
To
SMPS TEST 1: To Force Power Supply On.
Backlights
Disconnect P800 on Main PWB.
Jump pin 9,10,11 or 12 (5V) to pin 19 using a 10K
resistor. (Test Voltage Outputs 12V, 16V, and 24V).
Left Side
From Rear
SMPS TEST 2: Jump pin 19 to pin 20 (INV-ON).
(Ballast and all voltages should turn on).
P402
P401
Master Power Switch
Bottom Left
Back From rear
P3 "Front IR/LED" P3000 "Side Key"
Pin Label STBY Run
KEY 1 3.3V 3.3V
1
Gnd Gnd Gnd
2
3 KEY 2 3.3V 3.3V
4 Gnd Gnd Gnd
42LH20 INTERCONNECT DIAGRAM
T-Con PWB under shield. Be sure to reinsert screws
before operating set with shield removed.
TO TFT MODULE
CN4
Gnd
Protect
FL3
3.3V D13
L1
STBY Run Diode Check
0V .6V ~ 3.3V 1.68V
0V 0V Open
0V 3.8V 1.6V
0V 21.4V 0.71V
Gnd Gnd Gnd
0V 12.3V 0.96V
Gnd Gnd Gnd
5.14V 5.14V 1.67 V
5.14V 5.14V 1.67 V
Gnd Gnd Gnd
Gnd Gnd Gnd
0V 4.98V 0.886V
P201
*PWM DIM
st nd
1 2
Pin 22 will vary
Test Test
according to OSD
P201 P201
Backlight setting. 0.3V
23 24 23 24
0% to 3.4V 100%
INV
F501
21 22 21 22
ON
20
19 20 19
17 18 17 18
15 16 15 16
13 14 13 14
11 12 11 12
9 10 9 10
5V 5V
7 8 7 8
5 6 5 6
3 4 3 4
2 2
1 1
PWR PWR
Use P700 Side to
insert resistors
6.3A / 250V
AC IN
A/C Fuse
F100
SK102 SK101
N
L
Front PWB Assembly
P3 P3000
Diode Check Diode Check
1.1V Open
P3000
Gnd Gnd
1.1V Open
Gnd Gnd
Warning:
TO TFT MODULE
CN3
16.9V
Gnd
LED1
D14
L2 Protect
T-CON PWB
UC1
FL3
(TFT Driver)
U9
1) 0V
2) 1.8V
3) 3.3V
F1 (12V)
CN5
63V/1.5A
Set In Stby: LD1 Off
Anode 0V Cathode 0V
Power On: LD1 Lit
12V to T-CON Pins
Anode 3.3V Cathode 0V
2, 3, 4 and 5.
Set On: LD1 Off
LVDS
Anode 3.3V Cathode 1.3V
Far left pins 2, 3, 4 AND 5 for CN5 are
12V from Main PWB LVDS 12V Switch.
P700 "Main" to P201 "SMPS"
Pin Label Diode Check Pin Label
1 n/c n/c 2 PWR_ON
3 Gnd Gnd 4
5 Gnd Gnd 6
For Stand-By
7 STBY 5V 1.1 V 8
STBY 5V
and Run
STBY 5V 1.1 V
9 10 STBY 5V
voltages, see
11 Gnd Gnd 12
P201 Chart
13 12V 2.1V 14
15 Gnd Gnd 16
17 Open 18
24V
n/c n/c
19 20 INV-On/Off
21 A.DIM 2V 22 Err Out
23 n/c *PWM-DIM
n/c 24
P1204 "Main" to P1
"Front IR/LED"
Pin Pin Label
SCL
1
SDA
2
Gnd
3
4 KEY 1
(Interface)
KEY 2
5
P3 5V STBY
6
Gnd
7
IR Receiver
Gnd
8
P1
Power Button
IR
9
Gnd
10
3.3V STBY
11
Power On/Off
12
P801 "Main" to CN5 "T-CON"
Pin LABEL SBY Run
1 Gnd Gnd Gnd
2 Gnd Gnd Gnd
3 *PWM-DIM 0V 3.1V
4 OPC-OUT 0V 3.3V
5 Gnd Gnd Gnd
See LVDS Video
6 TXA3+ 0V 1.2V
Waveforms
7 TXA3- 0V 1.2V
On Back of page.
8 Gnd Gnd Gnd
9 TXAC+ 0V 1.2V
10 TXAC- 0V 1.1V
11 Gnd Gnd Gnd
12 TXA2+ 0V 1.1V
LED1
13 TXA2- 0V 1.2V
14 Gnd Gnd Gnd
15 TXA1+ Gnd 1.1V
*Pin 3 PWM-DIM 3.15V (Max 100%) to 0.6V (Min 0%) Customer's Menu Backlight setting.
However, this is not used on the T-CON PWB
IC704
L726
Q706
Q701
PWR On L710
IC705
Q706 Switch
(12V LVDS)
IC107
(5V General)
IC601 IC701
IC105
P700
IC601 (1.8V_Amp)
IC702 (3.3V_ST)
IC702
Diode Check
IC100
Reset BCM
1.87V
Video
IC600 Processor
Gnd Gnd
X100
Q702
Mstar
Audio
Gnd Gnd
Inv-On 12.00Mhz
1.1 V
Control
1.1 V
Gnd Gnd
Main (Digital) Board
12V 2.1V
Gnd Gnd
24V Open
1.9V
Grayed Out ICs are located on Back of the PWB
Open
Open
To Speakers
To Front
P600 P1204
Control
IC101
P1204 "Main" P1 "IR/LED"
C
(Flash Memory)
STBY Run Diode Check Diode Check
1-2 (0V)
3.3V Gnd 3.3V 1.14V 2.4V
3-4 (0V)
B E
5-6 (0V)
3.3V 3.3V 1.14V 2.4V
n/c
KEY 7-8 (3.2V)
Gnd Gnd n/c Gnd Gnd
3.3V 3.3V IC105
0.13V 1.1V Open
(HDCP EEPROM)
3.3V 3.3V 0V 1.1V Open
1-2 (Gnd)
5.1V 5.1V 0V 1.13V 1.5V
3 (5V)
5-6 (0V)
Gnd Gnd Gnd Gnd
4-7 (Gnd)
Gnd Gnd Gnd Gnd
6 (1.2V)
7 (0.8V)
4.8V 4.8V 0V Open 2V
8 (5V)
Gnd Gnd n/c Gnd Gnd
3.29V 3.29V 1V 1.0V Open IC107
(Power Det)
0V 3.29V 1V 1.0V 2V
1 (3.28V)
2 (Reset) .3V
3 (Gnd)
Diode Diode
Pin LABEL SBY Run
Check Check
Gnd 16 TXA1- 0V 1.2V 1.1V
Gnd 17 Gnd Gnd Gnd Gnd
1.1V 18 TXA0+ 0V 1.1V 0.8V
Open
19 TXA0- 0V 1.2V 1.1V
Gnd 20 Gnd Gnd Gnd Gnd
1.1V 21 OPC-EN 0V 0V 1.1V
1.1V 22 LVDS-SEL 0V 0V Open
Gnd 23 Gnd Gnd Gnd Gnd
1.1V 24 Gnd Gnd Gnd Gnd
1.1V 25 Gnd Gnd Gnd Gnd
Gnd 26 Gnd Gnd Gnd Gnd
27 LVDS 12V 0V 12.1V 1.6V
1.1V
1.1V 28 LVDS 12V 0V 12.1V 1.6V
Gnd 29 LVDS 12V 0V 12.1V 1.6V
30 LVDS 12V 0V 12.1V 1.6V
1.1V
IC1003
P801
IC1000
IC1002
*
LD1000 Illuminates
indicating Tuner PLL
IC503
is locked.
IC100
LD1000
IC101
IC1004
X1005
8vsb/QAM
24 Mhz
19 Video
16 SIF
15 (5V)
13 DIF -
12 DIF +
4 (5V)
1
TUNER
IC601 IC702 IC705 IC1000
(1.8V Amp) (3.3V_ST) (1.26V_VDDC) (1.2V_PVSB)
1 (3.2V) 1 (5V) 1 (0.78V) 1 (N/C)
2 (1.8V) 2 (3.3V) 2 (Gnd) 2 (3.2)
3 (0V) 3 (0V) 3 (5V) 3 (3.2V)
4 (5.9V) 4-5 (N/C)
IC704 5 (5V) 6 (1.2V)
Q701
(3.3V-FE) 6 (1.3V) 7 (0.8V)
(PWR ON)
1 (0V) 1 (0.78V) 7 (1.3V) 8 (Gnd)
2 (Gnd)
2 (5V) 8 (3.16V)
3 (5V) IC1003
3 (5V)
4 (7.4V) Q706 Switch (5V-Tuner
5 (2.12V) (12V LVDS) source)
IC701
6 (3.28V) (5V General) 1 (12V)
1.8V_DDR
1 (5V) 2 (Gnd)
7 (3.28)
1 (N/C)
8 (5V) 2 (0.48V) 3 (8.94V)
2 (3.18V)
3 (0.48V)
3 (3.18V)
Q702
4 (6V)
4-5 (N/C)
(INV ON)
5-6 (12.3V)
6 (1.87V)
1 (0.6V) 7-8 (5V)
7 (0.8V)
2 (3.82V)
8 (Gnd)
3 (Gnd)