Hi Nzdong
Check the fuse in the Tcon PCB and the lead to it
(the fuse will be a solid state one)
if ok make shore you have voltage to the t con pcb
I got this LG 32" LCD TV from a friend and it does not work. The fault symptom is, after plugging in the power cable, the front status LED will turn GREEN and after a few seconds the backlight of the LCD will automatically be turned on (without any button press). Then, it will stay in this state without anything being displayed. Pressing the buttons on the TV does not make any difference. I tried to connect a DVD player to its AV port and playing the DVD. No video being displayed. No audio can be heard.
I downloaded the service manual for this TV from the internet, but still doesn't have a clue what can be wrong. The power supply PCB in the TV looks okay to me (no bad caps) and all the voltage rails seem to be working. The service manual contains the block diagram and schematics for the main board, which is multiple microprocessors design with a CPLDs.
Does anyone have any experiences repairing this TV? What should I start looking?
The service manual can be downloaded from
Last edited by nzdong; 13-06-12 at 04:22 PM.
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Hi Nzdong
Check the fuse in the Tcon PCB and the lead to it
(the fuse will be a solid state one)
if ok make shore you have voltage to the t con pcb
Oh chriss, you should adv if that SMD Fuse is gone it prob the pwm control IC and they're very hard to find
Just kidding, it's prob fine just replace the fuse
When I explained to the guy what avatar I wanted, that wasn't what I meant!
CHRISS (14-06-12)
Hi Chriss, thank you for your information. The tcon PCB is the bottom PCB with all the AV connectors? There are four main PCBs in the TV (1) Power Supply (on the left) (2) Main processor PCB (in the middle) (3) AV connector PCB (at the bottom) (4) Tuner PCB (on the right). Does this fuse connect between the power supply PCB and the AV connector PCB?
The Tcon board drives the pixels of the LCD panel and is located normally at the top middle of panel and under a metal plate
look for flat lead or cable with lots of terminals on the main pcb then follow it up to the tcon pcb,
the will be a long skinny plug with about 30 or so connecters (may even be a flat lead but think set to old for that)
PS dont think you will find it in service manual as the tcon is part of the panel,
Hi Chriss, I know which board you are talking now. If the t-con board is faulty, it will cause this behaviour with un-responsive button press? For example, once the TV is on, I cannot turn off the TV with the ON/OFF button.
Hi nzdong
the tcon communicates with the main pcb i have had it lock up the processor before with A blown fuse,
This is just a starting point,
The common fault is the power supply caps but you say that all voltages are ok and no bad electro caps ?
so next step if tcon fuse and voltage ok is to look for caps on main pcb if look ok i would use a hair dryer and heat it up see if get a response
if you have a oscilloscope i would check all the clock frequency (look for the crystals had them stop oscillating before and locking set up) to see if all oscillating
if all seem ok get a price on a new main
chriss
My issue is somewhat different. TV turns on and has sound, backlight flashes briefly and then fails. If retried a few times it always comes on.
I've fully recapped power supply. Is the backlight supplied from power supply or is there a separate inverter board board. Obviously I'm working without a circuit diagram.
regards,
Glenn
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