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i have a tv that doesnt light the backlights, how should i go about fixing it? Answered

its a 40" Haier LCD TV, me and my dad picked it up at a disposal place, when we brought it home and tested it we figured the tv had some issues with th screen, we feared it might be like the 26" tv we got that just turns on and shuts off.

luckily, it does not have such a issue, i checked and it is just the backlight that has a problem.
and, from further investigation, it appears the ccfl's are not getting any power from the inverter board.
the inverter is split into two parts it seems, there is a lrge inverter looking component on the power board which has two wires that connect to the board the ccfls connect to, which has numerous smaller inverters on it. a interesting discovery was that the to wires from the larger inverter piece get bridged when they reach the sub-board.

im assuming its the board with several smaller inverters, because it is getting -12v of power, im not sure if thats normal but ive never seen a inverter setup like this before so its hard to tell. my camera battery is dead at the time of this post but i wil get pictures put up so people can see what im dealing with.
the tv was made april 27th 2009.
it has 8 CCFL's in it, which seems like a lot but im not exactly sure.

so i was wondering what the most efficient way of repairing it would be:
-replace possibly damaged inverter board with a new one
-replace CCFL's with a LED light strip (im leaning toward this)
-replace bad inverter board with a set of replacement inverters (8 in this case)

what do you guys think?


i called around and..
no inverter board available.
but the power board is....
$306 PLUS shipping and handling.
same goes for the main processing board.
i think this TV might return to the curb.

Most commonly -- look for blown capacitors on the inverter board(s)...that might just fix your problem - otherwise, you need to find some sort of on-sense wire that tells the inverters to power up - and use that signal to power an array of leds. There are literally hundreds of led projects on ibles and I'm not going to beat a dead horse explaining how to wire leds.

yes theres a LED backlighting ible rght in the related column.

the capacitors are all in operative condition, and there are 4 lines going from the power board to the inverter board, with connectons labeled LD, GND, FB, and VCC, on the power boards connector it says VCC is 12v", so im not sure what it means by that but when i test it with a multimeter i get -12v. same with FB, but i get 0.010V on the LD line, im guessing thats the problem but like i said, not knowing the power architecture of the TV makes it a bit more difficult.

if worse comes to worse i am probably going to buy some white LED stripping from dealextreme.

My thought is that .1v is actually a data line with a pulsed serial signal...

if thats the case then LD would mean light data? but if its not being sent the right info then the bulbs wouldnt turn on right?

I wouldn't say light data...but without knowing exactly it could be anything.


6 years ago

You might want to Google the numbers on the units. Very often you will get at least a source of replacement parts. Sometimes you will find articles related to a problem such as what you have.
Personally I would not plan on changing the configuration with something else but rather just fix what is broken. When they designed it I am sure they tried to get the best balance of light that they could. A darker area of screen would be a guaranteed consumer return. So anything you try to replace the backlight with would probably not work correctly.

the inverter pieces on the sub board dont appear to have any sort of number on them, but the larger inverter does have some sort of number on it. unfortunately after googling the tv model, i found absolutely no results about anyone having backlight issues with this tv, just links on amazon and other online stores, i found out its a $750 TV.
but im not too keen on replacing a part that failed after just maybe 2 years of operation, so long as i can get the right balance it would certainly be feasible to use LED light stripping, but while i agree the CCFLs would probably be better for the TV, i dont see why a set of replacement inverters wouldnt work, just so long as i can find out what the output voltage is on the original inverters.