LG 42LH20 Service Manual page 36

42LH20 P700 Main Board to Power Supply P201 Ballast Turn On Circuit
42LH20 P700 Main Board to Power Supply P201 Ballast Turn On Circuit
POWER SUPPLY
BALLAST
SECTION
To Backlights
1.2Kv
P402
P401
Hot Gnd
Ballast
Power
380V
160V
Ballast Control IC
Drive Control On Back of PWB
The Error Line will: Pulse high when the backlights 1
backights attempt to fire again and it pulses high. This happens 4 times, on the 5
P201
7 8
Stand By 5V
Reg
9 10
20
On Back of PWB
IC301
Controller
2
380V
Reg
12V
13
Reg
160V
14
Reg
24V
17
Reg
18
22
IC600
24
21
VBR-A (Analog Dimming)
VBR-B (PWM Dimming) Manipulates the Backlight Brightness via Customer's OSD.
This line is not used.
Manipulates the Backlight Brightness via the BCM Chip. Darker Picture, Darker Backlights to facilitate
improved Contrast Ratio. 0.6V ~ 3.3V Range
st
P700
7 8
STBY5V
R714
9 10
100Ω
20
3.8V INV On/Off
PWR
2
4.89V
R704 4.7KΩ
13
12V
14
17
STBY5V
24V
18
ERROR-OUT
22
0V
L733
PWM-DIM
24
0.3V~3.3V
L700
A-DIM
21
1.67V
attempt to fire, if they do it goes back low. If the do not, it goes low, then the
th
attempt it goes high and shut off the television
36
MAIN PWB
R717
3.3KΩ
+5V General
R719 R759
1KΩ 0Ω
Q702
Q701
R706 R703
Q700
R201 100Ω
Active 5V
R189 100Ω
R743 100Ω
R185 1.2KΩ
R704 4.7KΩ
IC100
BCM
R244
100Ω
G5 INV-On/Off
GPIO 136
R237
GPIO 134
100Ω
E5 RL-ON
GPIO 197
E8
ERROR-OUT
AB13
PWM-2
AB12
PWB-0