Vizio E65-E3 Dead after backlight replacement

[Diah]

Re: Vizio E65-E3 Dead after backlight replacement

EDit: because you cant refund them i guess, you can try this theory which i didn't try it before... but the principle of it make sense.

you add DO-35 type glass zener diode ( signal switching diode ) with specification such Maximum Reverse Voltage 100V, and Maximum Forward Current 400mA. they are very cheap round 5 cents each.. and solder them on each diode where the points you have on the strips as you made test before.

give it a try.

[RDC55]

Re: Vizio E65-E3 Dead after backlight replacement

this is wrong references you linked.. you should read the threat to the end, where the OP put in led with zener then it work. i dont need to argue any more about this all up to yours mind. Last words...

ALL TV brands Type LED BACKLIGHT should had zener.

the zener not only for protection. its much important as you think.

Diah first of all I appreciate your contribution to this forum and you have much to offer. And, I don't think anyone is disputing that TV LED's will for the most part, maybe even all have a built in zener. And, since the set was working before the LED's were replaced, it is not a bad assumption that the replacement LED's are causing an issue.

But, since we are all here to learn and help each other please explain why missing zeners would cause the LED's not to illuminate. Telling me or others "its much important as you think" does not give a constructive explanation as to its purpose and why being missing would cause a shutdown.

The AS3820 controller can shutdown if:

1. It detects an open in the string
2. It detects a short in the string
3. It exceeds a predetermined thermal limit

So, if the LED's illuminate with the LED tester then one of the above still has to be occurring. Now we all know that LED testers are not as robust as the actual circuit, so it is conceivable that LED's could open or short with full current applied resulting in a shutdown. That said, a zener that is not there is in no way a contributor to one of those conditions. So, once again, can you please explain why the missing zener causes the LED's not to illuminate?

[Diah]

Re: Vizio E65-E3 Dead after backlight replacement

can you please explain why the missing zener causes the LED's not to illuminate?

first i want to admit as all of you noticed my poor English because i am not a native English speaker. if i could write the whole explanation of TV LEDs circuit design with another language will be better. so i used only to put FACTS sentences which cant be change by any TV brand used LEDs.

however let me explain it in points the reset each can search with his own language. also to avoiding any mistake by typo.

You can read my post #51 when i suggest theory of adding signal switching diode with specification to OP. (however i dont know if it works or not but let take this adding zener in focus of the words ( Signal switching ) and compare this to RGB LED, which can illuminated different color such as in mobile or TV indicator. they all work in simple words regard to script ( signal /Freq and currents )

back to the TV backlights, we can see always if the BL direct type or edge the amount of LEDs unit at each group same amount except full array LED at new design of TVs.

with zener as there reserve V & reserve Am there will be total resistances pre calculated at LED design circuit, any change of this R (if low only) the circuit will shutdown. from this point we can always if the there OPEN = R low if we add any resistor end to end on this low LINE after the circuit, it will work again ( TEST IT SELF at time you have OPEN LED ) this for 1 example

2 example the way the backlight controlled by SW to decrease or increase. its SCRIPT (signal / Freq ) only this zener will communicated with it when the circuit send it out.. at this time fc will reduced or increased depending on the booster signal.

at the end, this zener not only protection.. its the hearts of the LED. if there no circuit will be blind nothings go on. also NO NO TV with LED backlight will work with out units build in zener. any one write some TV or not all he is wrong.

there are another mathematics calculation not good place over here to listed them as its for circuit designer.

[nomoresonys]

Re: Vizio E65-E3 Dead after backlight replacement

Some good info about backlight circuitry and potential fixes:

https://masterelectronicsrepair.blog...msung-and.html

[alfatv]

Re: Vizio E65-E3 Dead after backlight replacement

Some good info about backlight circuitry and potential fixes:

https://masterelectronicsrepair.blog...msung-and.html

Nice article, here are some links about zener diodes:
https://cdn.badcaps-static.com/pdfs/...2fe2cd513d.pdf
https://cdn.badcaps-static.com/pdfs/...e6dc79de40.pdf

Bottom line, they are used for protection and to keep the rest of LEDs working in case of single LED burnout.

[alfatv]

Re: Vizio E65-E3 Dead after backlight replacement

there are another mathematics calculation not good place over here to listed them as its for circuit designer.

I am a circuit designer, please list it here.
Also please share links supporting your theory.

[Diah]

Re: Vizio E65-E3 Dead after backlight replacement

I am a circuit designer, please list it here.
Also please share links supporting your theory.

look here an example which make me avoid going deep in explanation when you against the info that TV LED backlight should contained zener.. .. between now you call it theory. and the theory only was what i wrote as suggestion to OP, not the info i answered RDC55 ... so No need to add any info or comment.. just ignore my post and remain on yours believe please. as you are electronic circuit designer.

[alfatv]

Re: Vizio E65-E3 Dead after backlight replacement

just ignore my post and remain on yours believe.

We are talking about science here, not religion.
You are making strong statements, would you mind to share article, datasheet, application note?

[RDC55]

Re: Vizio E65-E3 Dead after backlight replacement

Do you think there is a workaround soultion? adding diodes in line maybe? If i tell the seller they work when i test them but when they are installed they do not.......they are going to tell me to kick rocks. Wish i still had the old ones.....to be 100% sure.. i also tested a samsung and a lg led strip i had laying around and they both tested with a zener.

Wondering if you had a plan or had gone any further. I will likely pull the panel from the 60 inch E60-E3 this coming weekend. I should have LED's arriving by Friday (from Ebay) that I can check.

I was also curious if you are seeing the LED's turn on ever so briefly when power is applied, or if you monitor LED power on the Power Supply does it go high for just an instance? And, do you currently have the panel out?

And, does anyone know the function of the pin labeled "VSNS" on the power supply? This is the only pin that could possibly shut down the Power Supply other than the PS-On pin or AC-DET, both of which are at the correct level per your measurments.

[RDC55]

Re: Vizio E65-E3 Dead after backlight replacement

OK, so I think the VSNS signal on the Power Supply is tied to the FB1 / FB2 Power Supply Feedback on the AS3820 LED controller on the Main CCA. Per the AS3820 datasheet this pin is an analog output used to dynamically control the output of the Power Supply.

I disconnected that wire at the input to my Power Supply on the E60-E3 and the backlights operated normally, and the voltage at the VSNS was still 2.4 volts in that open state, so it read the same with or without the wire??

The best I could do to support this is to look at prints for the E60-C3, which uses the same LED controller. The E60-C3 also has a power supply schematic, but unfortunately a very blurry version.

[a460guy]

Re: Vizio E65-E3 Dead after backlight replacement

No i havnt gone any further yet. When i monitor the voltage at the led connector at power on..it does not go up at all. just starts at 0 and drops to -.007. and i put the panel all back together...3 kids running around the house ..that is not safe(for the panel)

[RDC55]

Re: Vizio E65-E3 Dead after backlight replacement

OK, so I tested the Power Supply as a stand alone unit. It is a bit more difficult since the standby voltage is 16 volts.

I created a resistor divider from standby 16 volts to gnd so that the center would be near 5 volts and could be used to simulate the PS-ON signal. I used a 1K and 2.7K resistor, but a variety of values could be used keeping the objective of a 5 volt PS-ON signal - up in value would be better if you don't have these values.

With PS-ON active at near 5 volts the PFC voltage rises to the 360 volts expected value and the LED voltage is activated, in my case it is 16.2 volts. So this verifies that externally only the PS-ON signal is needed to activate the LED supply.

So, since your PS-ON signal is behaving you should have PFC boost voltage and LED voltage. The only other thought which I can't really test (I am a bit reluctant to short the supply) is if the LED voltage output is driving a short, such as a pinched wire or such to chassis ground.

You could do the test with the resistors to check the stand alone power supply.

Or, before doing that check the LED power pins out of the Power Supply for a short to chassis.

And, one other thought if you don't want to do the resistor check you could remove the 4 LED power wires from the Power Supply connector while leaving everything else connected - maybe the VSNS wire too just to leave no doubt. Turn the TV on and check the voltage at the LED pins on the Power Supply, and also check PFC boost voltage.

[Diah]

Re: Vizio E65-E3 Dead after backlight replacement

RDC55
please read the threat complete and take look on the photos he posted at post'27, he had full function TV except the BL because he bought from Ebay cheating strips. hope your order will be not from same seller which they mounted LEDs on the strip belong to swimming pool not for TV.

[budm]

Re: Vizio E65-E3 Dead after backlight replacement

I guess I don't quite get the purpose of the zener. I agree, most all TV LED's will have a zener, but it is never conducting unless the LED fails open. Therefore, its purpose is to keep the string active in the event that an LED does fail open, or prevent an overvoltage condition if somehow the string is connected with the wrong polarity - which might be destructive without resistive current limiting.

@budm is quite the reliable source of information on this site, and in this thread he comments that not all LED's have the zener.

https://www.badcaps.net/forum/showthread.php?p=806674

The other issue is what is causing no boost voltage. Yes, perhaps LED issues could cause a shutdown (and good troubleshooting always asks what was the last thing I did), but when I disconnected 5 rows the circuit did not function that way, and boost voltage was normal.

And, just in case anyone is interested the numbers on the Power Supply IC's on the bottom:

U101 PFC Controller - FAN7930BG
U1 guessing standby SMPS Controller - EA18363 - KZ60921 - TXD6241
U301 guessing LLC controller for LED voltage - MSP1626 - HR1001 - G483801.8

LED Controller on the Main

U400 - AS3820E - 1618XAC
Mosfet Driver - 09N10 - 6HGE

I only fixed a couple thousand LCD TV's and monitors with LED light source, as you can see my picture, the pile on the left of the LED strips from broken TV screens DO NOT have have Zener protection diodes, the pile on the right has LEDs with Zener protection diode. The purpose of the Zener is for ESD protection and reverse polarity protection as shown in the Mouser link. Zener is not needed for the backlight LED to work.

[Diah]

Re: Vizio E65-E3 Dead after backlight replacement

the document above related to the publisher Kevin Tseng was in year 2004 at that time, there are no LED TV in production at all, search after the history of LED TV after LCD.

innoteck LED year 2010.

[budm]

Re: Vizio E65-E3 Dead after backlight replacement

The first commercial full-array LED-backlit LCD TV was the Sony Qualia 005 (introduced in 2004).
A first dynamic “local dimming” LED backlight was public demonstrated by BrightSide Technologies in 2003, and later commercially introduced for professional markets (such as video post-production). Edge LED lighting was first introduced by Sony in September 2008 on the 40-inch (1,000 mm) BRAVIA KLV-40ZX1M (known as the ZX1 in Europe). Edge-LED lighting for LCDs allows thinner housing; the Sony BRAVIA KLV-40ZX1M is 1 cm thick, and others are also extremely thin.
The company I work for deals with commercial markets (higher price) long before they are implemented in consumer market (lower price), it is great for me to get to work and see the stuff for the commercial market before the general public people get to see them.
White LED history: 1995
https://www.led-professional.com/bus...-80th-birthday

[a460guy]

Re: Vizio E65-E3 Dead after backlight replacement

Removed the 4 led power wires and turned on. still same result.. then i checked them for short to chassis and no short. but i started poking around and found this guy shorted to ground on pin #3...none of the other 4 on the board are....did i find something?! or is this normal.

[nomoresonys]

Re: Vizio E65-E3 Dead after backlight replacement

Optocoupler, look up the datasheet for specs, simple testing video there: https://www.youtube.com/watch?v=Jax7BIr7SMU

[Diah]

Re: Vizio E65-E3 Dead after backlight replacement

a460guy:

with out headache. and you could damage parts.....
you wrote before you have strips for LG samsung, make diy one from tested working LEDs of samsung strip (Not LG ) with same amount of LEDs of 2 groups LED- share 1 LED+ to pass on the socket you have and test one line... see how the circuit will feed currents to the tested line.

[RDC55]

Re: Vizio E65-E3 Dead after backlight replacement

Removed the 4 led power wires and turned on. still same result.. then i checked them for short to chassis and no short. but i started poking around and found this guy shorted to ground on pin #3...none of the other 4 on the board are....did i find something?! or is this normal.

That is normal as that pin ties to DC rtn. However, with the four wires removed and you verified 5V PS-ON was there at near 5V then I can't see how it can be anything but a defective Power Supply. The test I did (hopefully the 60 inch is the same) as a stand alone supply confirmed that to get PFC boost and LED voltage all that is needed is PS-ON high - no LED's need to be connected.

You can add in your case of testing the AC-Det also needs to be valid as the Main needs to send the PS-ON command.

Did you also disconnect the VSNS pin with the other four just to be sure?