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Crumbtrail TV Forums: TV Equipment: TV Repair Forum:
Vizio M470NV LED LCD Help Needed!

 

 


70JUDGE
New User

Oct 14, 2011, 5:31 AM

Post #1 of 5 (2683 views)
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Vizio M470NV LED LCD Help Needed! Can't Post

I have a Vizio M470NV LED LCD TV that turns on,shows the Vizio logo,then the screen goes dark with sound,and a picture if you shine a light on the screen.I know on a traditional LCD TV there is either an inverter,or a set of them that light up the screen,and can go bad,but what about an LED LCD TV?What lights up the LED bulbs?Does the whole screen need to be replaced?Any help is greatly appreciated.Thank You very much!
Tyler



jts1957
Veteran


Oct 14, 2011, 6:15 AM

Post #2 of 5 (2682 views)
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Re: [70JUDGE] Vizio M470NV LED LCD Help Needed! [In reply to] Can't Post


Quote
What lights up the LED bulbs?


I'll bet it's a voltage. Crazy


-------------------------
Location: Far, Far Away


70JUDGE
New User

Oct 15, 2011, 3:55 AM

Post #3 of 5 (2666 views)
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Re: [jts1957] Vizio M470NV LED LCD Help Needed! [In reply to] Can't Post

Somehow that wasn't the answer I was looking for.
Does the TV have,or need an inverter to light the LED bulbs?Is the inverter built into the power supply?
Can the LEDs be replaced?Are they inside the screen like the CCFLs are?
What are the odds of a bad LED bulb versus a bad power supply?
The fact that the TV shows the Vizio logo before going dark,does this mean the LCD screen,T-Con,and Mainboard are alright?
Is there a Service Manual somewhere,or is it too new of a TV?
@
Thank You very much!
Tyler



t0nito
User

Oct 15, 2011, 11:02 AM

Post #4 of 5 (2663 views)
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Re: [70JUDGE] Vizio M470NV LED LCD Help Needed! [In reply to] Can't Post

Well, though I'm not familiar with LED tvs I do work on laptops and on them the LED screens don't have any seperate power supply. Power to the LEDs come from the motherboard through the screen connector. Obviously the bulbs aren't burned out because you can see the logo before they blackout. Also LEDs rarely burn out unless for some reason they are being fed with a higher than its rating voltage.

I would try looking for a firmware update for that tv and install it first. Just make sure you download the correct one for your tv and follow the instructions thoroughly or else you can brick your tv.

If that won't solve it only then I'd look for hardware faults.


70JUDGE
New User

Nov 24, 2011, 7:04 AM

Post #5 of 5 (2606 views)
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Re: [t0nito] Vizio M470NV LED LCD Help Needed! [In reply to] Can't Post

I can't update the TV,because I really can't see much on the screen when it goes dim.
Does anyone know where I might find a set of replacement LEDs?The numbers on them are 3660L-0348A Housing(L),and 3660L-0349A Housing(R).They also say LG on the LED strips themselves.I need two of each.
I tried a different power supply,and it did the same thing.Next I tried a set of LEDs from a broken panel that someone had online.Before taking the panel apart,I plugged the new LEDs into the new power supply with LEDs outside the TV,and they lit up,and stayed on.
When I took the panel apart,and replaced the LEDs,I put the old power supply in the TV instead of the new power supply I used to test the new LEDs with thinking there was nothing wrong with old one because it didn't fix the problem,and it did the same thing again.
I tried using the new power supply after,and it didn't make any difference.The only thing I can think of is by using the old power supply first instead of the new one,I burned out the new LEDs,and by the time I put the new power supply in,the damage was already done.
I even tried to set the original set of LEDs up outside the TV like I did with the new ones,and all of them light up,but when they go out,one strip is completly out,and the other three strips have a few lit up here,and there,and they are real dim.It also does this for a split second as soon as I press the power button before they come on full brightness for a few seconds,and then go off.This happens with bothe power supplies.
The funny thing is the backlight on wire still has 3VDC,on it as well as 115VDC to each of the LED strips.There are also three other wires to each LED strip that have anywhere between a little over 10VDC,to a little over 12VDC.This is with both power supplies,so I don't know what in the original power supply would be burning out the LEDs,or what is turning the LEDs off.If the main board is,shouldn't the voltage on the backlight on wire go away?If the LEDs,or one of them are bad,why are they all lighting up?Also,what is the 10 to 12 volts for on the other three wires for each of the LED strips?Shouldn't the 115V be enough?
There are two LEDs strips on the top,and two on the bottom.Each strip has 66 LEDs,and has a trace that runs the length of the strip.There are three other traces that each go a third of the way down the strip.On the power supply the connections are marked VLED 1-1 1-2 1-3,VLED 2-1 2-2 2-3 ETC. for each of the four LED strips.With the LEDs plugged in,I get 115VDC on each of the VLED,and anywhere between a little over 10VDC,to a little over 12VDC on the numbered wires.I would unplug the connectors,and test the power supply,but I don't want to take a chance on the power jumping to another pin like it did on me with the Proscan 40LD45Q.Maybe that was because it was a higher voltage.
The only thing I can think of to do is to get another set of LEDs,and try them outside the TV with the new power supply like I did before,and if they work,put them in with the new power supply.
Any help is greatly appreciated.Thank You very much!
Tyler


 
 
 


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