I'm in the process of repairing a Haier L30CV6 flat panel TV. I thought there was a problem with the inverter board, as the unit remains powered on but the CCFL tubes only flash on for a second, then remain off. However, having replaced the inverter with a known working one, I still have the original problem.
Can anyone tell me if all the CCFL tubes light if only briefly, then can I presume none are faulty? Also, should the 24v rail be 24v, as it's currently reading 25.3v?
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Hello, the most common problem on this set is a backlight problem. about 85% of the time it's the backlight inverter board that fails, but sometimes the CCFL tubes in the LCD panel can fail, if anyone of the 8 to 20 CCFL tubes depending on screen size fail, the set shuts down. you can find the inverter boards on ebay or shopjimmy if want to try that for under $50,,,,,thanks, Terry
As you said when there is no backlight the problem is either inverter or power board. In some case the main controller board may be responsible. You need to test the parts to find out what part is responsible. Testing is done tracking voltage from PSU to inverter. Voltage to inverter is usually supplied by the higher VDC line from PSU. Here broad description of how to test the three
parts: Before proceeding... The TV can be repaired at component level or replacing boards, depending on your skills and experience. If you want to repair at component level, after diagnosing the faulty board you test components and circuits individually. In that case to test inverter in full you will need an oscilloscope to read the phase of inverter AC section (oscillators or IC must be tested).
Note: If Inverter has voltage out to CCF lamps, then the parts mentioned above are OK, in that case you have a faulty LCD panel. The TV is usually not worth repair as the LCD panel is expensive. LCD panel faults are not common.
Here replacement parts for most flat panel TV models:ShopJimmy.
hi, You have to check the back light section of your lcd tv. All lcd tvs have back light to illuminate the pixels. Two types of back lighting are there CCFL (cold cathode fluorescent Lamp) and LED. In your tv its CCFL. CCFL need high voltage 1000V or above . For providing this high voltage there is inverter stage ( back light inverter). Also there will be 12 or more CCFL behind the lcd screen. If any on of there CCFL failed the there will come a gray bar noticeable only when there is hight light.
There will be two causes for this problem. 1.CCFL is faulty. 2. The inverter transformer driving CCFL is faulty.
You have to check the inverter fist. For conforming which one is faulty do the following. There is 10 independentconnection for every two CCFL from the inverter board. Try interchange the two nearest connection. And watch is the line is shifting or not after every interconnection. You have to try by interchanging all the nearest to connections for CCFL.
If the line shifted then the inverter board is faulty. If the line stays there then the CCFL is faulty. Normally there will be problem with inverter transformer. If the transformer is faulty then you have to replace the inverter board as a whole. ok
Your tv has problem with its back light inverter stage. All LCD TV have back light to illuminate the pixels. There are two types of back lighting CCFL(Cold CathodeFluorescent Lamp) and LED. In your tv its ccfl. As it is ccfl it need a high voltage above 1000v. To provide such a high voltage there will be an inverter stage in all lcd tv with ccfl back lighting. Normally in LCD tvs there will be three boards such as Mother board , Back light inverter board, and power supply.
In your tv the ccfl back light inverter stage is faulty. There will in inverter transformers in the inverter board. As it is high voltage transformer there is possibility of its winding get shorted. If so it will drain a high current from the power supply and the protection circuit will shut down the voltage to the inverter board. check the inverter board first. Also there is possibility of bad electrolytic capacitors in the inverter board will lead to this type of problem.
First of all check the supply voltage from the power supply to the inverter board. Change the electrolytic capacitors in the inverter board and in the power supplystage. If the problem is not rectified then you have to replace the inverter board.
I would recomend replacing the 11 caps on the inverter as 90% of the time its failed capacitors on the inverter. If you shine a bright light into the screen can you see the pic? Thats usually one of the first things I do when I suspect bad caps on the inverter.
Hi, Please measure all windings again and see if there is one lower than 900ohm. All CCFL might seem working but only for one second before the protection circuit cuts in. By the way, there is something that I would like to know, what is the type number of your remote control?