Our company is manufacturing backlight signs for restaurants, and our current process involves keeping the original TV power board to light the backpane.
We think the TV powerboard is "overkill" to just run the lights and also has more value sold for another TV.
Does anyone have experience with Universal power boards like these ones (sold on Alibaba)?
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Finally, what's the best vocabulary word when the OLED crystal sheet is removed and you have only the frame and compact fluorescent / LEDs?
On Thursday, September 28, 2017 at 11:56:53 AM UTC-4, Robin Ingenthron wrot e:
rent process involves keeping the original TV power board to light the back pane.
has more value sold for another TV.
sold on Alibaba)?
emoved and you have only the frame and compact fluorescent / LEDs?
Yikes. Do you mean that you use discarded TVs, remove the LCD, and use the back light as a basis for a sign?
If that's what you're doing and don't want to use the existing power/LED dr ive board, take a current measurement of the existing LED array with the TV running. Build/buy a current regulated supply that will supply the LED ar ray with about 30% less current than the TV did (those are overdriven and h ave a very short life as installed). The voltage required can be up to 300 volts depending on how many LEDs are used and if they're all arranged in s eries, so every application is different.
Using the original supply can be easier, but you will have to externally en able the back light on command line and most of these power supply boards w on't turn on the LEDs unless they receive a PWM signal from the main for th e brightness feature. You'll either need to keep the TV main board functio ning or build a pwm signal generator.
If you get the run current wrong on the LEDs, they won't last.
Not sure what you're trying to say about OLEDs, but we refer to the screen assy sans LCD display as a light box, although there's no standard definiti on that I'm aware of.
I think a far easier plan would be discard the TV components entirely from inside the light box and buy LED strip lighting and a control box (Alibaba, ebay). This way you can be sure you won't over drive the LEDs.
Thanks John-Del. That is similar to the instructions we got from the Ghana Africa guy who makes these. I was hoping that the Alibaba link ( finder.com.cn/Products/Details/LCDPower.htm ) will work.
Here is a link to a Powerpoint done in Ghana by the USA apprentices we sent to work under Master Technician Karim Zakaria.
na Africa guy who makes these. I was hoping that the Alibaba link ( finder .com.cn/Products/Details/LCDPower.htm ) will work.
nt to work under Master Technician Karim Zakaria.
This is a lot more complicated than sourcing an LED supply and connecting i t to the existing LED array inside the screen.
If you want to source a universal supply to run existing LEDs, you must be sure that it can run independently from the donor's original main board. V ery few power supplies will turn on the back lights without a pwm adj/brigh tness signal from the main board to set LED drive current.
One that I can think of that will run independently from a TV main board is this power supply included in recent certain RCA and ProScan TVs (possibly others):
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This supply will run and output LED drive with only AC supplied. The on co mmand can be enabled by using a 470 ohm resistor between the power supply's standby line (pin 8) and the on/off line (pin 9) of CON2 to turn the power supply on. You'll need to do the same between pin 8 of CON2 and pin 3 of CON4 to power up the LEDs. This will enable the backlights with no input to the "adj" line although the output of the supply will be reduced (which is a good thing to ensure LED longevity).
The first problem is that this supply needs a balanced load on the LED outp uts, so you'll need to divide the LED strips into equal pairs. If the dono r TV has an odd amount of LED strips, this may trigger LED shutdown (some d o, some don't). You may have to rewire the strips in order to present two identical loads to the two output terminals of the LED output on the power supply (CON5) Another problem is that TV power supplies adjust it's LED vol tage output in order to regulate to a specific current, and so some LED str ings might require more voltage to reach the required run current than this particular supply is capable of.
The point I'm trying to make is that you aren't going to be able to teach t rained monkeys to do this job if you intend to make these signs in quantity . The workers will need to possess a working understanding of electronics and basic design. Almost every job will be a custom one as there is an alm ost infinite number of LED TV designs in the market. If the assembler mana ges to get it running but doesn't monitor run current, the sign may fail wi thin minutes or hours.
It would be far easier to buy LEDs on flexible ribbons, buy the controller that is used with these types of LED ribbons, and install these inside the screen. You can even program color changes and brightness as well as remot e control of on/off with these:
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If the LEDs you install have an uneven appearance on the TV screen, you can pop the lens' off the donor LED strips and carefully glue them over the de ad center of the new LED.
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