What is the voltage for led backlight from the power supply board/led inverter


You may be able to repair the board instead of buying a replacement board. If you are up to a little soldering it may save you a good bit of money for the repair. If you are interested just take a few pictures of the boards and email them to us at [email protected] We will check them out and give you some pointers on what to do. Most power supply issues with the blinking power lights are caused by blow capacitors on the power board. These are fairly easy to replace and the replacements are less than $20 usually. To get an idea what capacitors are and what will need to be do to repair you unit check out our pages at :http://www.ccl-la.com/blog/index.php/capacitors/ You may want to look over the repair guides for other units we have posted too. If you need parts we can also supply them for you. If you have any additional questions just contact us at: [email protected]

I hope this helps, If so please rate our solution.

Corporate Computer

You forgot one very important piece of information in your question, the make and model...without it its just a general answer and that is from 40 to 280VDC

If you can feed 3.3v to BL_ON line (but you have to disconnect the line from the main board first) and the backlights doe come on then you inverter is OK. What you can do is not connecting the BL_ON line to the inverter board, and feed the 3.3v to it so the backlights will come on and see if you get the pictures OK, I have a feeling you have bad main board that is not sending 3.3v to the inverter board and more likely you will not see the pciture on the screen either. I have seen this symptom before and it is the main board problem.

What is the make a nd model of the TV? You can look here for SCH. WWW.ELEKTROTANYA.COM

Basic LCD monitor and TV troubleshooting guide:




Failed TV and Monitors pictures: http://s807.photobucket.com/albums/yy352/budm

Learn about bad caps: http://en.wikipedia.org/wiki/Capacitor_plague

Parts: www.shopjimmy.com

Capacitors kit: http://lcdalternatives.auctivacommerce.com/Default.aspx he can make you a set of caps.

Or www.digikey.com, just make sure to use caps with low ESR, 105c, high ripple current and long life rating such as PANASONIC FM or FC series.

just replace what failed.

I replace the surface mount FETs on the inverters.

check if their is a signal on voltages around 3.3v at the inverter board if none their is a problem in the board which is in the processor.


Above is a link for a service manual.

Hi, well I applaud you for starting in the right place, The power supply, as, if, that isn't right nothing else can be. But you simply cannot do anything without a Service Manual. In this it has everything one needs to repair the set. OK if it is shutting down, after that amount of time, of working and then faulting, then it is most definitely a "Thermal" problem, the way we "Find" problems such as this is "Freeze Spray" you use this on each component that is suspected of being the "Culprit" and you will soon,find that errant component. Now also not every fault is a Capacitor, I see many, many people that think, that Capacitors are always the "Culprit" now while that may be true in a few cases, a faulty Electrolytic Cap, or ordinary, Cap goes faulty, this is only a SYMPTOM, something has damaged those caps causing them to "Fail". One MUST always find the root "Cause", otherwise if you just treat, the SYMPTOM, the "Cause" will just make the "Symptom" come back, in short order, as the prime cause still, hasn't been fixed., Now Capacitors hate AC ripple, or Over Voltage. Thats it. Oh.. and Heat, if these Capacitors, are too close to a Heat Source, then thats a prime cause of failure. Resistors, hardly ever go faulty,and if they do, it is generally obvious. However it doesn't hurt to check values with our Multimeter. Remember though resistors are made, with up to 20% tolerance from stated value, as such, are not too critical, unless in Timing circuits etc. Always check, the Values, of resistors, as with any other component, with the power OFF. Now Diodes especially "Zener Diode", are another thing to check, those and ordinary "Signal Diode" should always be suspect. next we have Transistors and IC's. The Transistors MUST ALL be checked to see if they have a good, "Junction" this is done, with our meter set to "Diode Test" and usually are about 0.6 to 0.7. With IC's you must check, voltage levels, or Logic Levels, going in and out, have a look at the circuit diagram, and it will tell you what they should be. It is a good idea to always measure the Power Supply voltages, see if a "Rail" is Low, that will be because some component has gone somewhat or all short circuit, to Earth, now, if the "Rail" is Higher, suspect an "Open Circuit" component, like a Diode, or Transistor. The voltages expressed in the manual are spot on, ANY variation MUST be investigated. I have been doing all this for over 30 years now, and I do indeed wish, we could have a set of "Symptoms" and be ables to say.. "Oh that;s the so-in-so and replace this" however unfortunately this although does happen, most "Symptoms" can have literally tens, of "Causes" all often "Interlinked" One simply has to do a methodical troubleshooting procedure, and always think, "are my Voltages Correct" as this is how, you Fix the problem, by making them so. Keep up the good work. If that link above doesn't furnish a Service manual, it is imperative you get one, even if you must pay for it. It will pay for itself in about 2 mins.

Gee it seems that you have replaced just about the entire "Guts" of the set, in the industry we call this the "Shot gun" method, however it seldom works in reality. One really needs to isolate the Cause, of the "Fault" and repair that and also any damage done by that. As if one doesn't remove the "Cause"
it will simply fault again when the "New" bit is connected up. One needs to get the unit going section by section, testing and proving the prior section before connecting up to the next, which also must be tested to make sure that what you are going to connect will NOT damage what you are connecting it to.

Also unfortunately, these LED's Blinks, are NOT an error code in actual fact.

What you need to do is use the service manual, and follow through the troubleshooting steps, to isolate and hopefully repair your problem.

Basically it is all about voltages and if they are correct, a Higher voltage than stated usually means a component is Open circuit or a very high resistance, whereas a Lower than stated voltage usually indicates a Short Circuit, or low value resistance component, is "Faulty". These are all in the SM, as are the waveforms that must be checked, it is indeed very difficult to repair electronics these days without specialised equipment and even though I have over 30 years experience i find it difficult, so good luck.

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