Vizio E500I-AB No Backlight has sound

[MisterD]

I posted this earlier but can not find it on here. not sure why..here we go again with more information..TV Screen went black while watching it. turned the tv off and back on..has a picture again for awhile..went black again.now does not have Backlights...has 123 volts DC at CN301 on LED1+ and LED2+ when tv is first turned on...leaving the volt meter hooked up the voltage starts dropping until it reaches about 67 volts DC, this occurs on both LED 1 and LED 2 pin connector CN301 as seen in picture....I remove the connector at CN301 and have the same results as far as voltage checks go...Thanks in advance.

[MisterD]

Re: Vizio E500I-AB No Backlight has sound

I tried doing the flashlight test with the menu screen brought up but could not see any image, later on I hooked up a Dvd player and pushed the input select on the remote control until I went through all HDMI inputs and finally found the right one..had sound but had the TV laying on it's face so forgot to do the flashlight test this time.

[CapLeaker]

Re: Vizio E500I-AB No Backlight has sound

your pictures are too blurry for me to read anything off the PSU. Also recheck the model number of the TV. So far I couldn't find an "AB". It should be some thing like "A1" or "B1". Sounds like a backlight LED problem to me. Does the LEDs turn on for a second when you turn the TV on?

[MisterD]

Re: Vizio E500I-AB No Backlight has sound

Sorry for the blurry pictures, this camera will not do good close up shots like it used to...I do Not see the LEDs turn on at all..I'm thinking one of the LED strings is open since the voltage drop at CN301 is the same whether the LEDS are connected or not.

[MisterD]

Re: Vizio E500I-AB No Backlight has sound

Model number is supposed to be E500I-A0 these are all zeros.......I CAN NOT edit the Model Number on this thread, how do I change it? anyone

[MisterD]

Re: Vizio E500I-AB No Backlight has sound

Posting this link for my own reference or for anyone else that has the backlight problem...https://www.youtube.com/watch?v=UxR8-xztdGs

[CapLeaker]

Re: Vizio E500I-AB No Backlight has sound

Hmm... well... it tells me that you have 2 open LED strings. So either there is something wrong with the wires and jumpers that go from the PSU to each LED strip, or a bunch of bad LED's. So that panel has to come unfortunately apart. It's not a replace some board fix.

[MisterD]

Re: Vizio E500I-AB No Backlight has sound

Probably open LED Strings, it belongs to a friend of mine and he leaves the TV on almost all day long every day. it is now 5 1/2 years old...Is it necessary to do the flashlight test to see if there is video on the screen?as we know there is No Backlight and the voltage to LED 1 & 2 is normal but drops due to no load as if the LED Strings are open...I would think the video is ok, it did have sound with a dvd player running to HDMI port 1 and it had a great picture before the backlights went out.

[budm]

Re: Vizio E500I-AB No Backlight has sound

That power supply board has two boost converters, one for each LED string, so if you put the LED connector back in place and then leave the black probe on the chassis and red probe on one of the two LED 1 + then turn on the TV while watching the meter to see how high it goes up to and then back down to, record the value then turn off the TV and the repeat 3 more times on the other 3 pins of the LED connector, report the result.

[MisterD]

Re: Vizio E500I-AB No Backlight has sound

Voltage Readings at CN301 on the Power Supply Bd.

LED1- 19.5 V when tv first powered on then it dropped to 0.1V

LED1+ 128 V when tv first powered on then it dropped to 66.9 V



LED2- 12.1 V when tv first powered on then it dropped to 0.4 V

LED2+ 128 V when tv first powered on then it dropped to 66.9 V

Reply for budm

[budm]

Re: Vizio E500I-AB No Backlight has sound

So the feeding Voltage to the boost converter is 66.9V.
It may have shorted out LEDs on the LED 1 - because the Vdrops on the PWM control is higher than the LED 2 -.

[MisterD]

Re: Vizio E500I-AB No Backlight has sound

If I unplug the connector at CN301 the voltage at both LED1+ and LED2+ starts out at about 67 volts and maintains that same voltage without any drop. I did not test the LED1- and LED2- with the connector unplugged...I'm not sure if this information helps...Is there a was to test the LED strips without the LED Tester like Shopjimmy sells? Thanks.

[MisterD]

Re: Vizio E500I-AB No Backlight has sound

also I tried doing a flashlight test with the Menu and could not see anything..should I try the DVD Player again and this time do the flashlight test while I hear sound? ...what if I don't have a picture would that indicate something else wrong and not the LED Strips being the problem?

[Andrew F. Ali]

Re: Vizio E500I-AB No Backlight has sound

Voltage Readings at CN301 on the Power Supply Bd.

LED1- 19.5 V when tv first powered on then it dropped to 0.1V

LED1+ 128 V when tv first powered on then it dropped to 66.9 V



LED2- 12.1 V when tv first powered on then it dropped to 0.4 V

LED2+ 128 V when tv first powered on then it dropped to 66.9 V

Reply for budm

From the voltage reading seen here it is definitely a LED backlights problem and not any other fault/s. You would have to strip the Panel down to reach the backlights and take a note of the filter sheets order of which goes first to the last and where the plexi-sheet is placed.

[MisterD]

Re: Vizio E500I-AB No Backlight has sound

So you are saying it's the backlight LED's themselves causing the problem, and not the power supply or anything else and that I will need to disassemble the TV to access the LED Strips by removing the panel/screen keeping everything in order so it all is placed back correctly.

[CapLeaker]

Re: Vizio E500I-AB No Backlight has sound

that is correct. You have to take the panel apart.

[Andrew F. Ali]

Re: Vizio E500I-AB No Backlight has sound

That is correct.

[MisterD]

Re: Vizio E500I-AB No Backlight has sound

Okay, I will get to that sometime soon, could be next week. too many things going on right now. I know I will be very careful during disassemble and reassemble. will disconnect ribbon cables from screen and keep everything in the same order, it's my friends TV so I will get him to help with the fragile screen since this is a 50". don't want to crack it...I saw a youtube video where a guy used 3 9 volt batteries hooked in series to get 27 Volts. he used this to test each strip of 10 LED's..I might try that since I don't have the LED Tester. Thanks, will post what I find later.

[MisterD]

Re: Vizio E500I-AB No Backlight has sound

My friend and I disassembled the TV Today, I took three 9 volt batteries wired in series by plugging them into each other, then ran two leads for positive and negative off the batteries..this gave me 27 volts. I hooked up the leads with the correct polarity to test each LED Strip of 10 each LED. 4 of the strips lit up all the way across and two of them did not light at all. so my friend ordered a full set of replacement LED strips from Shopjimmy. once these come in we will replace them and reassemble the TV..Thanks to all for the help. will post results.

[MisterD]

Re: Vizio E500I-AB No Backlight has sound

Watching a video from Shopjimmy shows using double sided tape on the led strips, my friend did Not order any of this tape. is this necessary? I thought the new replacement Led strips already had double sided tape..I want to make sure we have everything we need..where can I get the tape..what is the correct width of the tape for this Vizio Model E500I-A0 with Panel type LG Display LC500DUG JFR1 budm please advise