I am looking for a way to check the LEDs and also how to get the white reflector off. It looks to be glued down and I don't want to harm it. Anyone know how I can check to see which LED bar is bad?
Back - light problem. Check and replace damaged component/s at its back-light inverter board, or replace this board as card basis. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts. It will be best to replace the inverter board as card basis.
http://electronicshelponline.blogspot.com/
SOURCE: I got a Sony Bravia
http://www.smpcshop.com/KDL-40WL135-KDL-46WL135-p-8895.html
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.
Im having similar problem and with my limited knowledge of lcd tvs and the voltages ALL being good except the pwr on or sw on voltage from the main board to the power supply which tells it to switch everything on Im guessing that something is going wrong on the main board. In the condition where it freezes it (the power on V) which switches everything on i get varied voltages such as 2.5 or 3 or (the normal 5v) and then when nothing powers up (blank screen) i read 0v on pwr on voltage but all my other voltages are corect (24v to inverter, 12 v to main board, 5v, etc.) Im guessing from researching this is that there is in improper voltage somewhere in the main board circuit. I have been unable to find it so i may order another board and post back.
SOURCE: When testin a power supply or led board on tv do i test dc or ac with multimeter?
Your power supply board is working if you get audio and imgaes.
You test AC only the AC side of the transformer before the Rectifier Diodes. Everything after the Diodes will be in DC.
did you get to see any spec of backlight as shown in
LCD LED TV Repair No Image Blank Black Screen Flashlight Test How to Fix...
the t-con board would be the problem if there is sound and back light working then is more likely to be this board.
SOURCE: LG TV 39LN5300 - What is normal voltage at LED connection to power supply?
ok so the problem is not with the power suppkly it is with the leds inside the panel they are in strings and usually only a few of them are your problem see the link for led prices http://www.shopjimmy.com/auo-t390hvn02-2-led-strips-8-strips.htm
Testimonial: "Had thought that it was the LEDs but with only minimal knowledge was not sure. I don't know why the voltate would be over 200 volts. As for ordering LED strips I have heard that they were panel specific, and have heard that they weren't. The link you provided is out of stock, unfortunately. Is basically any 39" strip useable or does it need to be matched to the panel? Thanks again."
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