Vizio E470i-A0 LED Strips

[NeedsMoreFlux]

Re: Vizio E470i-A0 LED Strips

I modify power supply to limit current because I resale. Vizio overdrives the leds. Probably to make them fail after warranty

How do you do that?!?!??!?!!?!

[NeedsMoreFlux]

Re: Vizio E470i-A0 LED Strips

OP, You are missing a few steps.

I'd get the T.V. apart and test that you are actually getting voltage-probably 20-30 volts D.C. on each strip. Divide the voltage your meter says by the number of LEDs on the strip. Yours could be 3, 3.3, or 6 volts.

Then pop off one of the lenses covering the led. warm up the underside of the board with a hair dryer or hot air station first. I set mine at 180F for this.

Then use a caliper to measure the dimensions of the LED. Could be 3528, could be 3030.

Do you know what those numbers mean?

This guy sells them on ebay in 10pcs for $9. he probably also sells them in 20pcs. They look like 3030's, probably 3-3.3 volts:

https://www.ebay.com/itm/10x-LEDs-fo...gAAOSwwzhZWr0X

[NeedsMoreFlux]

Re: Vizio E470i-A0 LED Strips

You can scrape the coating and expose the copper. The solder job looks bad so maybe resolder.

Yes, exactly!


The led is the positive rail, there is a gap in the copper trace under that lense/LED. if you pop off one of the lenses you can see the copper stops just under the legs on either side of the LED.

You can scrape off a tiny bit of solder mask on either side of the LED and test the LED.

The jumper wire is the negative trace.

I really need to make a youtube video and just-copy paste!

[karthur]

Re: Vizio E470i-A0 LED Strips

OP, You are missing a few steps.

I'd get the T.V. apart and test that you are actually getting voltage-probably 20-30 volts D.C. on each strip. Divide the voltage your meter says by the number of LEDs on the strip. Yours could be 3, 3.3, or 6 volts.

Then pop off one of the lenses covering the led. warm up the underside of the board with a hair dryer or hot air station first. I set mine at 180F for this.

Then use a caliper to measure the dimensions of the LED. Could be 3528, could be 3030.

Do you know what those numbers mean?

This guy sells them on ebay in 10pcs for $9. he probably also sells them in 20pcs. They look like 3030's, probably 3-3.3 volts:

https://www.ebay.com/itm/10x-LEDs-fo...gAAOSwwzhZWr0X

I measured the LEDs and they are 2.8 x 3.5 mm. I guess that means they are the 2835 variety. I checked the voltage earlier and found the Vout1 and Vout2 to be 130 volts. 54 total leds, so that works out to be 2.4 volts/LED. Is that the voltage you are asking about?

I have these LEDs on order. https://www.ebay.com/itm/322611404018

[budm]

Re: Vizio E470i-A0 LED Strips

I measured the LEDs and they are 2.8 x 3.5 mm. I guess that means they are the 2835 variety. I checked the voltage earlier and found the Vout1 and Vout2 to be 130 volts. 54 total leds, so that works out to be 2.4 volts/LED. Is that the voltage you are asking about?

I have these LEDs on order. https://www.ebay.com/itm/322611404018

The 130V reading is ref to GND with working LED or without LED?
You cannot just divide the supply Voltage by the Vf of the LED because the Cathode return of the LED string is not directly connected to GND, it is connected to the PWM Controlled MOSFET and the current sensing resistor to maintain the constant current through the LED string so you will also have the Vdrops on the MOSFET and the current sensing resistor.
The Vf of each LED is affected y the amount of current flowing through the LED, at 50mA the Vf will be 2.7~2.8V but at full 400mA the Vf will be about 3V.
You have two LED string with 27 LED each based on your pictures, so 27 x 3 = 81 V vF +20V on the MOSFET, so the output Voltage with load will be around 100V or so.

[karthur]

Re: Vizio E470i-A0 LED Strips

Here is what I did to fix the repair. There are 4 places where they cut the board rather than doing the piggy-back method.

I was finally able to see the trace that should go to the "-" side of the LED.... and continues on to the "+" side of the next one on the strip. The large wire on the LH side is connected to that trace.



I put electrical tape under them so they would not short.

Kirk

[dskall]

Re: Vizio E470i-A0 LED Strips

How do you do that?!?!??!?!!?!

Here: https://www.badcaps.net/forum/showthread.php?t=65978

[karthur]

Re: Vizio E470i-A0 LED Strips

The 130V reading is ref to GND with working LED or without LED?...

The 130 Vdc is ref to GND with NON-working LEDs.

[budm]

Re: Vizio E470i-A0 LED Strips

That is what to expected when there is no load, it is the constant current circuit.

[karthur]

Re: Vizio E470i-A0 LED Strips

Just ordered a set of those from ebay. Also watched a YT video on how to make a tip for my soldering iron to remove the LED.

If I was doing a bunch of these repairs, the hotplate would be the way to go.... but for just this one panel, not really worth the $40.

Hopefully this will work out.

Thanks for all the help. This site is great!!

I got the replacement LEDs and got the bad ones replaced last night. Only had 7 in the set that were bad.

A few things I learned. The YT video that shows how to make a foot to go on the soldering iron does not work to remove the old LED. I used a heat gun to take off the old ones. I tried to use the heat gun to put the new ones on, but hard to hold the gun and hold down the LED so the air does not blow it off.... and see what I was doing. Ended up using a soldering iron to put them back on. I would hold the soldering iron on the "+" side of the LED and it would solder on both + and - side to the trace.

When I was re-soldering in the new ones, the new LED would just break in half. I wasn't pushing on it or anything. I may have been getting it too hot, but as soon as the solder started to flow under it, I would take off the soldering iron.

This is my first time to solder LEDs to a trace, so I did learn a few tricks. Was I doing something wrong to cause them to break?

Thanks

[dskall]

Re: Vizio E470i-A0 LED Strips

With soldering iron probably only one side was molten. You need both sides molten to not stress led. You can turn airflow down to keep from blowing led off or heat strip from bottom.

[SLK001]

Re: Vizio E470i-A0 LED Strips

I use two soldering irons to place LEDs by hand - one on each side. I find it beneficial to preheat the area where I am going to place the LED with a heatgun. I heat the area to around 180 F, the use the irons to finish the placement. I imagine that you overheated the LEDs that you place with only one iron. One side got seriously overheated, thus causing the part to fall apart. The LEDs are just high-temp plastic and are not super tough.

[karthur]

Re: Vizio E470i-A0 LED Strips

I use two soldering irons to place LEDs by hand - one on each side. I find it beneficial to preheat the area where I am going to place the LED with a heatgun. I heat the area to around 180 F, the use the irons to finish the placement. I imagine that you overheated the LEDs that you place with only one iron. One side got seriously overheated, thus causing the part to fall apart. The LEDs are just high-temp plastic and are not super tough.

Before I placed the led on the trace, I put a tiny amount of solder on the "+" and "-" trace. Then I placed the LED on there and heated the "+" side. When the solder melted under the "+" side, I removed the iron. The stress from the raised up area on the "-" side is probably what caused it to break like dskall said. Sounds like two irons is the ticket.

I did get it all back together last night and it now works. There is one bright spot where I think the diffuser lens is not centered on the LED. I am going to fix that today. In all it was a pretty easy fix, just takes a little time, but I am happy with it.

A big THANK YOU to everyone for the help.

[augiedoggy]

Re: Vizio E470i-A0 LED Strips

I have a Vizio E470i-A0. Classic symptoms no picture but good sound. I did the "flashlight" test and do have a picture playing in there. I pulled off the back and tested the power supply board /LED board voltages. I checked Vout1 and Vout2. Both of these show voltages of around 130VDC. From what I have been reading the LEDs are bad.

What is a good source to purchase these LED strips?

Any tutorials on how to go about replacing them? I have the back off, but that is as far as I went (dont want to damage it futher).

I have read to replace ALL of the strips, but is it ok to find the bad one/ones and just replace them? Why do all of them if they are not bad?

Thanks,
Kirk

I use the led from the many failed LG strips I have laying around but ive bought new ones on ebay too.. makes no difference. once one fails the chances of more being stressed by the voltage change are high and others will likely fail in the near future.. I have this same model set Ive repaired twice so far... best way to fix it is replace all the strips.

I recommend if your not going to do that , that you buy extra leds since youll be likely replacing them a couple at a time over and over. these use the 3v 250ma leds , same as the lg versions (this vizio like many is made by LG's manufacturer) I bought 100 leds for $8 on ebay myself,