Test LED TV strip

[Lord of the Strings]

I have a sharp TV model LC-60LE810UN, I already change all the boards and still have the same problem- flashing the logo one short one long -so the only thing missing before I quit from this TV is check the LED strip (I already remove one from the TV. The strip have a set of 30 LED's and a two wire connector I would like if anybody know how I can check this LED strip?
Some history, when I replaced the power board, I access the service code and the screen was on, then I turn off the TV, and from that day I can't get anymore the service code or the screen lite.

[budm]

Re: Test LED TV strip

You will need constant current source (to limit the max current to about 20mA) for testing power supply that can put out >102V (3.4V x 30 White) to test the whole string or you can test each LED by utself.
http://www.maximintegrated.com/app-n...ex.mvp/id/3256

[ecking767]

Re: Test LED TV strip

I have a sharp TV model LC-60LE810UN, I already change all the boards and still have the same problem- flashing the logo one short one long -so the only thing missing before I quit from this TV is check the LED strip (I already remove one from the TV. The strip have a set of 30 LED's and a two wire connector I would like if anybody know how I can check this LED strip?
Some history, when I replaced the power board, I access the service code and the screen was on, then I turn off the TV, and from that day I can't get anymore the service code or the screen lite.

Have you check your T-CON board? I had a Sharp that didn't power on but I had the power LED flashes some code. Changing the T-CON board fix the problem.

[Lord of the Strings]

Re: Test LED TV strip

How can I tested by myself, can I use a voltmeter, or can I connect a ten 9v batteries and connect the strip?

[Lord of the Strings]

Re: Test LED TV strip

Ecking 767,
I just change the 3 PCBoards, first vthe power supply, next the T-con and last week the main board. All the PCBoards with a warranty to work.
The flashing error code is "Inverter/Lamp system failure". Any advice will be of a lot of help, I'm working in this TV more than a month.

[ecking767]

Re: Test LED TV strip

Ecking 767,
I just change the 3 PCBoards, first vthe power supply, next the T-con and last week the main board. All the PCBoards with a warranty to work.
The flashing error code is "Inverter/Lamp system failure". Any advice will be of a lot of help, I'm working in this TV more than a month.

to test you LED'S you can buy this C-DC 600W 10-60V to 12-80V Boost Converter.

search for this on eBay. But before you buy you need to know the working voltage for those strings of LEDs. I have this DC-DC 600W 10-60V to 12-80V Boost Converter and capable of output a little over 80 volts. Also I saw a seller on eBay selling LED lights for your LED TV

[tom66]

Re: Test LED TV strip

As a side note, no way that thing can do 600W.

[ecking767]

Re: Test LED TV strip

As a side note, no way that thing can do 600W.

well its work great for testing LED string. The main MOSFET is capable of handling 85 amps. SUP85N10 along with a UC3843A Current Mode PWM Controller. The output voltage always hold steady under any load of LEDs I'm testing.

[tom66]

Re: Test LED TV strip

well its work great for testing LED string. The main MOSFET is capable of handling 85 amps. SUP85N10 along with a UC3843A Current Mode PWM Controller. The output voltage always hold steady under any load of LEDs I'm testing.

85 amp with a heatsink and fan cooling.
Max temp 125C above ambient (25C), 40C/W, max power = 3.12W.
Max current therefore (I^2 * R) = ~17.5 amps without heatsink. Excluding switching, reverse breakdown and pulse losses.

The inductor is too small to handle 600W anyway, efficiency will plummet once magnetic saturation occurs, which will result in destruction of the MOSFET. The glass fuse will then explode, sending flying glass everywhere (a ceramic fuse is required in this application.)

[ecking767]

Re: Test LED TV strip

85 amp with a heatsink and fan cooling.
Max temp 125C above ambient (25C), 40C/W, max power = 3.12W.
Max current therefore (I^2 * R) = ~17.5 amps without heatsink. Excluding switching, reverse breakdown and pulse losses.

The inductor is too small to handle 600W anyway, efficiency will plummet once magnetic saturation occurs, which will result in destruction of the MOSFET. The glass fuse will then explode, sending flying glass everywhere (a ceramic fuse is required in this application.)

Well you are probably right lol, But I don't plan on going to the max. Most LED string draw about 250ma to 1amp. This board can handle that without breaking a sweat !

[Lord of the Strings]

Re: Test LED TV strip

I am going to order the test device, but it came from China and will be arrive until the end of July.It's possible to test the LED's when the strips are inside the tv?

[ijohannessen]

Re: Test LED TV strip

I am interested to know if you were able to test the LED strips with this boost converter without taking apart the TV. Where did you take the input voltage from?

[tibimakai]

Re: Test LED TV strip

I had a 40" with two long and five short error code and I couldn't fix it. I have just gave up. Sold it for parts.

[jbblackbird]

Re: Test LED TV strip

Did this get sorted out? I also have the LC-60LE810UN with the dreaded one long one short code. When I try the volume- and ch+ combo it doesnt do anything for me. I have the service manual and it doesnt say anything about how to reset error codes. Do I need to get this:
http://www.ebay.com/itm/600W-DC-Boos...item2c73195d6c

so that I may continue on trying to repair this set?

[electronicsurplus]

Re: Test LED TV strip

Many times the Lightstrips do run in series and have signal return lines which do report back to the main board to let the main board. IF one of the leds have failed the signal will advise the main board that there is a problem or failure causing a high or low to the protection IC, which results in the various failure codes

You can check each individual Led using 3.5 volts or the entire strip using 3.5 V DC times whatever number of leds in the particular strip. for example if there are 10 leds then 35v DC would be required

However, in some cases the led's in various TVs are run in sets. meaning they have individual circuits that run a small number of leds to keep the voltage requirements low and,

in some cases they also use a sort of loop back system

[R_J]

Re: Test LED TV strip

I've just checked a couple led strips, you can usually light the individual led's (although it will be dim) with the diode test on a meter.
If the led shorts the string usually still works except for that led, if the led goes open the the whole string (and most likely the whole panel) will not light.
Also you can usually scrape a bit of the white paint away on either side of the led on the strip so you don't even have to remove the lens to check the individual leds.

[electronicsurplus]

Re: Test LED TV strip

Does anyone know of a way to disable or disconnect the protect circuit to allow the strip to light in order to test to determine where the problem(s) is/are regardless?

[stj]

Re: Test LED TV strip

that's a bad idea, you could damage the remaining good led's

kjust connect a 3v lithium battery across each led in turn to test them.

[electronicsurplus]

Re: Test LED TV strip

We currently use multiple 9Volt Batteries connected - to + to multiply the voltage considering how many individual leds are in a particular strip.

For example if we have 30 led's in a strip then, for safety sake we consider that circuit to need 90 volts

So, we will connect 10 9 Volt Batteries together to obtain the needed 90 volts (Most Sharp LED TVs require 94 Volts. So 90 volts is safe

Take a look at the attached you tube video to see

https://www.youtube.com/watch?v=ZSJ4ETkLTF4

We have however, on occasion could not determine the exact amount of Led's in a particular strip (In this case we try 2 different methods) 1st we try locating the led strips either on eBay or Google and simply look at the picture and simply count them OR, we begin using lower voltages until one of the strips light. Usually starting at 27 volts and going up from there Or, we look at the LED Driver voltages when the LED Strip is unplugged and power the set on to determine the highest voltage and go from there

We have had some success by simply jumping the return wire from known working strip, while disconnecting or clipping the defective strip + & return wire to make sure the TV will work properly without

Although some technicians do not agree we have found that many TVs will operate satisfactory even missing one led (especially edge lit screens) without much notice at all. Just will not be as bright and vibrant as it was when new but, yet, still view-able.

At least this method does save many of these TVs from otherwise ending up in some landfill and, may allow someone the opportunity to enjoy a LED TV that could not otherwise afford such

Hope this helps someone or many people viewing this forum

[ENERGYSAVINGS]

Re: Test LED TV strip

Using a 3 volt source across each led is the safest, providing you have a current limiting resistor in series across it.