View Full Version : Trash Find: TCL L40FHDM12


Solid_State
02-16-2014, 10:29 AM
A friend of mine found a TCL L40FHDM12 sitting along side of the road in a box for a newer model TV

and of course it does not work :boring:

anyway the TV displays the TCL "splash" screen as soon as it is plugged in and it will then turn off. So I thought the power board was bad but with another board that I bought off of eBay the TV still does the same thing :tears:

The TV will turn on if the power button is pressed (either by a remote or the buttons on the side of the TV) but it just does the above

can a bad inverter board cause the above symptoms?


PS: I hate fixing flat panel Televisions

CoogarXR
02-16-2014, 05:30 PM
Are you sure it actually turned off, and it didn't just turn the backlight off? Turn it on, when the screen goes blank, hit the 'menu' button and point a bright flashlight at the screen and see if you can see the menu. If you can, it's the inverter or a bad CCFL tube.

Solid_State
02-16-2014, 09:05 PM
Are you sure it actually turned off, and it didn't just turn the backlight off? Turn it on, when the screen goes blank, hit the 'menu' button and point a bright flashlight at the screen and see if you can see the menu. If you can, it's the inverter or a bad CCFL tube.

I just tried that and yes when the screen goes blank it is off pressing menu or input or channel shows nothing on the screen so I am sure it is turning off

dr.ido
02-16-2014, 10:02 PM
Does the standy LED change color when the backlight goes off?

If not - seconding the inverter/backlight. It can be difficult to see with some panels and has caught me before.

Check the voltages at the inverter board (the pins are usually marked). If the 24V supply is present and there is 5V at the on/off pin the backlight should be on.

If you've ruled out the inverter check the voltages at the various voltage regulators on the main board. There are usually 1.8V, 2.5V and 3.3V regulators supplying various ICs. On 1117 type regulators the tab is output.

Pictures of the boards may help narrow it down if it's a set if seen a few of. These sets are rebadged/relabelled so often and the casings are so generic that I don't recognise them by model number.

Solid_State
02-17-2014, 12:23 AM
When the TV turns off the standby LED will go out (Its a blue LED unsure if is a dual or single color) but I can press the power button again and the LED will turn back on but then go out when the set turns back off

dr.ido
02-17-2014, 04:13 AM
In many sets it's is dual color (or 2 seperate LEDs behind a common diffuser), often red for standby and blue/green when on. If it is dual color watching it carefully can provide clues - the difference between the power supply itself shutting down and the set shutting down because of failed self test or a microcontroller problem.

Measure each supply rail at the power supply. Something may be loading a rail down causing it to shutdown. First guess would be the 12V rail (seeing as you have backlight and a splash screen you have 24V and 5V at least momentarily). I've had a shorted audio amp IC do this, but there are other possibilities. On some sets power for the audio amp is conveniently on a separate connector, so it's easy to pull it and see if it stays up (or at least stays up longer).

Solid_State
02-25-2014, 02:19 AM
It WAS the inverter board

I sent the power supply back so I now have a $25 40" 1080P Television :thmbsp:

Thanks