LCD TV Repair made easy #4
Monday, February 8th, 2010 at
11:41 am
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Filed under: 55-Inch Video Reviews
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I learnt lot of tips from your videos, thank you very much for shearing
The new bulbs worked and my tv problem is solved.
This inspired my to attempt to fix another samsung LCD with a slightly different problem. This tv has normal backlight and sound, but no picture. After powering on, the LCD is a dark grey color and slowly begins to fade to an all white screen. When i change the input source, the screen flashes and the transformer on the PCB starts humming. Also the led on the front is constantly blinking. Any ideas on this one?
the best you tube site I ever found?
keep up the good work… you happen to have block diagram how lcd-plasma tv works?
Sounds like your making great progress.
I reassembled the TV without the LCD panel, so I could see the lamps fire up. It turns out that one bulb is not lighting. I should have done this from the beginning. I have a nice picture of it, if you’d like to see.
Also I reassembled the tv without the lcd panel, so I could see exactly which bulb wasnt firing. Turns out it is the 3rd bulb from the top. I got a nice picture of it too if you’d like to see it. I should have done this before I bought the inverter. I think Ill just buy 2-3 bulbs and replace the ones that look like they’ll burnout next. I got a quote from ccflwarehouse for $12.95 a bulb. which was lower than $19.99 i found at 2 other sites. Ill follow up with the results
I bought a replacement inverter on ebay, but I got the same results, 1 second of backlight. I was able to return it, so I will buy some new ccfls and see if that fixes it.
Yeah he’s right. One bulb can throw off the inverter, remove the CCFL’s and one… maybe two will probably be really black on the ends. But, if you’re in there and replacing lamps you should probably do all of them
I would start by testing them on while they are soldered on the inverter board to see if its open or has real high resistance
Can I test them while they are still in the board?
Yes there is. Using your volt ohm meter you can put it on the resistance scale, and measure across the primary and secondary side to see it its open and or has any shorts. Since you may not know what the resistance should be, try measuring some of the other inverter transformers, and see how they read in comparison.
If you had what’s know as a ring tester that
is there a test I can try on the inverter transformers?
One additional thought. It could also be that just one of the inverter transformers has gone bad, and or the related circuitry which drives them. but they might not sell you a single transformer anyway. I have not repaired enough LCD sets to tell you which is more likely to be bad between the inverter board and the lights.
I can’t speak for every design, but I was told many of them have feedback circuits which turn off the whole set when one of the lights has a problem.
Also, if it is the CCFLs, do they all go bad at once? or could one bulb be the cause for the other 11 not to power on? Is it a series or parallel circuit? would I need to buy 12 new ones or just a few of them?
In your experience with samsung lcds, what part is more likely to be the faulty part? the inverter or the CCFLs?
Ive found both parts online, but I dont know which part I should pursue. CCFLs – $10 to 12 a piece. Inverter board $70. I got the bad TV from my dad, who was going to throw it out, so if I can spend about $100 and a few hours to get it running again, Id say its worth it.
Thanks
That trick with the hair dryer will not work if the capacitors are to far gone. Since you may not be able to get parts on your TV any way, it might be fun to see what kind of back light you can come up with on your own such as LEDs. I recently saw a youtube video on this. Perhaps more work than the TV is worth, but if your the experimental type it might make a fun project.
I’ve verified that the LCD is working after that one second of backlight using the flashlight trick. Im getting normal audio as well. After watching the video on capacitors, I tried the hairdryer trick on the 4 caps on the inverter board. I heated them up before turning the tv on, but the heated caps didnt do the trick. Also I tested the voltage to the inverter board and its reading 24.4V. According to a samsung troubleshooting guide on this model, its needs to be 24V. Thanks for the quick post
You can shine a light of your own behind the screen and see if your picture is there. That will at least confirm if there are additional problems other than the light circuit, but because of the way the feedback circuit works sometimes its hard to draw the dotted lines between the symptom and the cause.
I would start with the power supply capacitors and move on to the inverter board to see if your transformers are open or the lights themselves are bad. From what I’m hearing on the new LED sets they have a feedback circuit which can shut down the power supply if it senses a problem in your lights or the associated output transformers which often go open.
I have a Samsung LNT3242HX/XXA same problem as the 32″ westinghouse as described above. Im getting about 1 second of backlight when the TV is first powered on. Is that an inverter problem or a bad ccfl?
Thanks
Great videos! Keep them coming!
Here is a video where the gentleman modified his LCD back light to work with an LED.
watch?v=BExEo-d1qkc
I have almost the same problem. Westinghouse 32″ LCD TV Monitor almost 4 years old (picture is there but not viewable – you can see what’s on the display by shining a flashlight on the screen, audio is fine, no burnt wire smell). I’ve found lots of posts online pointing to replacing the backlight lamp; your suggestion that it might be a bad inverter board. Appreciate the insight and the videos – very helpful stuff and I especially appreciate the pop-ups you have added – nice job!
yes the tv is an lcd. The tv also smells like burned wires . It turns on but the picture is black. There is sound coming out of the tv. And thank you for the fast response!!!!!!!!!
A real common cause for the kind of problem you described, is that the back lights on the TV are not operating due to a bad inverter board, but it’s difficult to guess at problems like this with out seeing the set. I’m assuming this is an LCD TV.