Vizio E470i-AO - Backlight LED Problem

[grimacelord]

Hello. After reading this forum some and some searching online, I came to the conclusion that my Vizio had some problems with it's backlight LED's.

I was getting 130DCV when reading the pins for the backlight on the power board. The shopjimmy YouTube video I was watching, coupled with some previous threads on this model I read here, lead me to replacing the LED strips.

I ordered them online and they came today. I very carefully disassembled the display panel and was quickly disappointed to realize that although I had ordered the LED strips for the correct model, it wasn't quite the exact part number this particular model used for its LED strips. So the ones I purchased were useless to me. I should have disassembled it first and get the part numbers directly off of the LED strips themselves rather than rely on the part number of the TV. I suppose it really doesn't matter. When I later looked up the actual part numbers, the prices for the LED strips are astronomical. I'd never pay it.

So, not wanting to give up, I connected the original LED strips back up and saw that (from top down) #2, #3, and #4 was all out while the rest were fully illuminated. So I needed just 3 sets of LED strips it looked like, not a full replacement of 6 sets.

Troubleshooting further, I removed one of the single LEDs from the useless LED strip I purchased and replaced it with one of the "bad" LEDs on strip #2. No difference.

But then, I swapped a fully working LED strip (set #6) with one that was not working (#2) and now the roles have reversed. The strip that WAS working in its original position is now not and the one that was NOT working in its original position now IS (including the replacement LED I soldered in place).

So what am I looking at now? Are the connectors "#2, #3, and #4" on the LED interface board marked (6637L-0024A) bad? How do I verify this? Is it something else?

I've attached some pictures for you guys to look at to see what I mean. Thanks in advance for any help!

[dskall]

Re: Vizio E470i-AO - Backlight LED Problem

So if you are saying the connectors that the strips plug into are bad you can jumper around them

[budm]

Re: Vizio E470i-AO - Backlight LED Problem

You have two LED strings (LED 1 (Cathode return), VOUT 1 (Anode where boosted Voltage is applied to the LED string, same for LED 2 and Vout 2) that is why you have 4 wires to the power supply board), each string contains 3 LED strips which are connected in series.
I can see partial picture of the green termination board and I can see the connectors are connected in series but I need to see the whole long green board to see which LED strips are connected in series with the other two strip to form one LED string.
As you can see the connectors are connected in series so you can easily check to see if all the connections are OK or not using Ohm meter.

[dick_barton]

Re: Vizio E470i-AO - Backlight LED Problem

What voltages do you have at D9102, D9102A, D9202, D9202A, R9110, R9210

[grimacelord]

Re: Vizio E470i-AO - Backlight LED Problem

You have two LED strings (LED 1 (Cathode return), VOUT 1 (Anode where boosted Voltage is applied to the LED string, same for LED 2 and Vout 2) that is why you have 4 wires to the power supply board), each string contains 3 LED strips which are connected in series.
I can see partial picture of the green termination board and I can see the connectors are connected in series but I need to see the whole long green board to see which LED strips are connected in series with the other two strip to form one LED string.
As you can see the connectors are connected in series so you can easily check to see if all the connections are OK or not using Ohm meter.

I hope the attached image is not an absolute atrocity. I see exactly what it is you meant and followed your lead, taking readings of each series. Between almost every point, my meter would read 0.0 or OL, but would give the steady beeping tone. It was only the two marked in the picture that deviated from that. I hope you can make sense of the picture. I figured it might be the easiest way to show you the data. Let me know if you want exact readings of certain spots and I will get them to you.

What voltages do you have at D9102, D9102A, D9202, D9202A, R9110, R9210

D9102: 0.468
D9102A: 0.468
D9202: 0.467
D9202A: 0.468
R9110: 1.5
R9210: 1.6

Thanks guys!

[dick_barton]

Re: Vizio E470i-AO - Backlight LED Problem

The diodes look as though they feed C9102 & C9202. Looks like two identical circuits that would then feed the two led strings. One string of 3 strips working and the second string of 3 strips not working. I would have expected some of the voltages to be close to the DC voltage given on those capacitor. Unfortunately the picture in post #1 does not show their working voltages.

[budm]

Re: Vizio E470i-AO - Backlight LED Problem

I hope the attached image is not an absolute atrocity. I see exactly what it is you meant and followed your lead, taking readings of each series. Between almost every point, my meter would read 0.0 or OL, but would give the steady beeping tone. It was only the two marked in the picture that deviated from that. I hope you can make sense of the picture. I figured it might be the easiest way to show you the data. Let me know if you want exact readings of certain spots and I will get them to you.



D9102: 0.468
D9102A: 0.468
D9202: 0.467
D9202A: 0.468
R9110: 1.5
R9210: 1.6

Thanks guys!

The picture is too low resolution for me to zoom in and see the trace, Please up date with a new picture without any red lines.

[grimacelord]

Re: Vizio E470i-AO - Backlight LED Problem

The diodes look as though they feed C9102 & C9202. Looks like two identical circuits that would then feed the two led strings. One string of 3 strips working and the second string of 3 strips not working. I would have expected some of the voltages to be close to the DC voltage given on those capacitor. Unfortunately the picture in post #1 does not show their working voltages.

They read:

NFK
200V
47 uF

The picture is too low resolution for me to zoom in and see the trace, Please up date with a new picture without any red lines.

Got it! Attached!

[budm]

Re: Vizio E470i-AO - Backlight LED Problem

https://www.badcaps.net/forum/attach...7&d=1501773189

OK the 1 strip on the far left is connected in series with the two strips on the far right that is why you see those three strip light up as you are seeing right now in the picture in post 1. https://www.badcaps.net/forum/attach...0&d=1501714409
The other three thatare not on are connected in series to form a second set of LED string.

[grimacelord]

Re: Vizio E470i-AO - Backlight LED Problem

https://www.badcaps.net/forum/attach...7&d=1501773189

OK the 1 strip on the far left is connected in series with the two strips on the far right that is why you see those three strip light up as you are seeing right now in the picture in post 1. https://www.badcaps.net/forum/attach...0&d=1501714409
The other three thatare not on are connected in series to form a second set of LED string.

Ahhh! I understand now!

So what do I need to do from here?

[grimacelord]

Re: Vizio E470i-AO - Backlight LED Problem

Do I need to replace the green termination board or is this something that we can further troubleshoot and perhaps replace components to ultimately fix? Thanks

[budm]

Re: Vizio E470i-AO - Backlight LED Problem

So those 3 strips that are not lighting up are showing the series connection continuity between all 3 connectors?

[grimacelord]

Re: Vizio E470i-AO - Backlight LED Problem

So those 3 strips that are not lighting up are showing the series connection continuity between all 3 connectors?

I just measured again and the three that are not lighting up have an initial reading that seems to spike high. It's too quick for me to catch on some. On one of them it looked like 175, but on others, 1.8, but they all fall to ~0.3 or 0.4 eventually where they maintain and my meter gives off the audible "beep" that it's supposed to when continuity is there when I measure.

[budm]

Re: Vizio E470i-AO - Backlight LED Problem

I just measured again and the three that are not lighting up have an initial reading that seems to spike high. It's too quick for me to catch on some. On one of them it looked like 175, but on others, 1.8, but they all fall to ~0.3 or 0.4 eventually where they maintain and my meter gives off the audible "beep" that it's supposed to when continuity is there when I measure.

Are you testing them in Ohm mode? All the connection should show <1 Ohm depend on the probe's leads resistance.

[budm]

Re: Vizio E470i-AO - Backlight LED Problem

LED connectors wiring. As you can see how the connections are made, you should be able to check all the connection all the way to the the LED connect on the power supply board. All the connection should show <1 Ohm depend on the probe's leads resistance.

[grimacelord]

Re: Vizio E470i-AO - Backlight LED Problem

Are you testing them in Ohm mode?

Yep.

[budm]

Re: Vizio E470i-AO - Backlight LED Problem

See post 15.

[grimacelord]

Re: Vizio E470i-AO - Backlight LED Problem

LED connectors wiring. As you can see how the connections are made, you should be able to check all the connection all the way to the the LED connect on the power supply board. All the connection should show <1 Ohm depend on the probe's leads resistance.

See post 15.

Ok. Went back and followed your pic there with all of those test points and yes, you're right. All connections were <1 Ohm.

[budm]

Re: Vizio E470i-AO - Backlight LED Problem

If you swab ALL three of the strips that do not light up to the three location of the working strips, what do you get?
I have a feeling one or more LED strip has open circuit, that is why you should move ALL 3 non working strips to the location of the working strips.

[grimacelord]

Re: Vizio E470i-AO - Backlight LED Problem

If you swab ALL three of the strips that do not light up to the three location of the working strips, what do you get?
I have a feeling one or more LED strip has open circuit, that is why you should move ALL 3 non working strips to the location of the working strips.

Hey! A change!