Read LG 42LN5200 (CHASSIS:LT36M) Service Manual online
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4.5. V-COM Adjust (Only CDMS Module)
■ Why need Vcom adjustment?
The Vcom (Common Voltage) is a Reference Voltage of
Liquid Crystal Driving.
→ Liquid Crystal need for Polarity Change with every frame.
- Adjust sequence
■ Press “P-only” key, enter to power only mode. And Press
“yellow” key to enter module inspection mode. After then,
Press “number 0” key, Flicker Pattern is displayed.
(Or After enter Service Mode by pushing “ADJ” key, then
Enter V-Com Adjust mode by pushing “►” key at “13.
V-Com”)
■ As pushing the right or the left button on the remote
controller, And find the V-COM value Which is no or
minimized the Flicker.
(If there is no flicker at default value, Press “P-only” key and
finish the VCOM adjustment.)
■ Push the OK key to store value. Then the message “Saving
OK” is pop.
■ Press the “P-only” key to finish VCOM adjustment.
4.6. Outgoing condition Configuration
■ When pressing IN-STOP key by SVC remocon, Red LED
are blinked alternatively. And then automatically turn off.
(Must not AC power OFF during blinking)
4.7. GND & Hi-pot test
4.7.1. GND & HI-POT auto-check preparation
(1) Check the POWER CABLE and SIGNAL CABE insertion
condition
4.7.2. GND & HI-POT auto-check
(1) Pallet moves in the station. (POWER CORD / AV CORD is
tightly inserted)
(2) Connect the AV JACK Tester.
(3) Controller (GWS103-4) on.
(4) GND Test (Auto)
- If Test is failed, Buzzer operates.
- If Test is passed, execute next process (Hi-pot test).
(Remove A/V CORD from A/V JACK BOX)
(5) HI-POT test (Auto)
- If Test is failed, Buzzer operates.
- If Test is passed, GOOD Lamp on and move to next
process automatically.
4.7.3. Checkpoint
(1) Test voltage
①
①
3 Poles
- GND: 1.5KV/min at 100mA
- SIGNAL: 3KV/min at 100mA
②
②
2 Poles
- SIGNAL: 3KV/min at 100mA
(2) TEST time: 1 second
(3) TEST POINT
①
①
3 Poles
- GND Test = POWER CORD GND and SIGNAL CABLE
GND.
- Hi-pot Test = POWER CORD GND and LIVE & NEUTRAL.
②
②
2 Poles
- Hi-pot Test = Accessible Metal and LIVE & NEUTRAL.
(4) LEAKAGE CURRENT: At 0.5mArms
5. Local Dimming Function Check
Step1) Turn on TV.
Step2) Press “P-only” key, enter to power only mode and
escape the “P-only” Mode by pressing “Exit” key
Step3) Press “Tilt” key, entrance to Local Dimming mode.
Step4) At the Local Dimming mode, module Edge Backlight
moving Top to bottom Back light of module moving
Step5) confirm the Local Dimming mode
Step6) Press “Exit” key
Row Line
Column Line
C
LC
C
ST
Panel
S
Y
S
T
E
Y
S
T
E
M
Gate Dri
ve
I
I
C
Source Drive IC
Circuit Block
Timing
Controller
Power
Block
V
COM
Gamma
Reference Voltage
Gamma Reference
Voltage
Data(R,G,B) & Control signal
Control signal
Data(R,G,B) &
Control signal
Interfac
e
TFT
Power Input
Power Input
Data Input
Data Input
V
COM
Liquid
Crystal
V
COM
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