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Old Dec 01, 2006, 12:40 AM
That tree again!!!!
thanhTran's Avatar
Germantown, MD, US
Joined Sep 2004
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fixing back light inverter board

My LCD tv at home just went blank after 2 years of service. I gotta fix it. It seems the inverter board is bad, but I'm not 100% sure. The inveter board has 8 ballast to drive 8 neon tube. It has 24V power supply and 4 more wires for some purposes. One of those wires is the ON/OFF signal. The other 3 connects to the main board.

The problem with my TV's back light is that when I first turn on the TV, the light turns on for about 2 - 3 seconds then it turns off by itself. TV still has sound, and I could see some pictures if I shine a light at it. I wonder if the TV's brain turns off the lights because it senses something wrong or if the driver board itself does this?

I look at the inverter board, nothing seems bad or damaged. All the fuses look & check fine. The board is from an Olevia 30" LCD TV.

Anyone has anyidea or suggestion?

Thanks very much

Thanh
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Old Dec 01, 2006, 11:50 AM
York Electronics
Gary Warner's Avatar
Dallas Tx USA
Joined Apr 1999
2,505 Posts
The Olevia brand is a china import.

Give me the model number and I'll do a search on a subscription site I use. Most tv techs can't stand the china import models and won't work on them, so the database might not have much for us.

Gary Warner
York TV
--

Edit: I did a search w/o the model number. If this is the Syntax Olevia LT30HV then you might have luck talking to the factory at #1-888-796-8298. On the 28th of this month there has been some discusion about this model with the exact same problem, but no solution just yet. I did note that the backlight inverter board is about $40. The consensis is that it's the inverter PCB or the display panel. If it's the display panel, the factory is not selling it to us techs and it must be shipped to the factory to be replaced. They are getting $500 for an out-of-warranty replacment of the display pannel and someone noted that it's been taking about 5-6 months to get the sets back. Good luck and hope this helps.
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Old Dec 01, 2006, 12:18 PM
That tree again!!!!
thanhTran's Avatar
Germantown, MD, US
Joined Sep 2004
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Hi Gary,

Thank you very much for your help. I called Syntax yesterday but noone picked up the phone. I'll call the number you gave me here. To see if there is any luck this time.

The TV seems having pictures just fine when the backlight flash up briefly. So I think it's just the backlight controller is bad.

Here are some pictures of the board.

Thanks Gary

Thanh
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Old Dec 01, 2006, 12:34 PM
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USA
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At this site the fellow found diode D5 to cause the problem (had high forward resistance). His set would work for a couple of minutes then the invertor would shut off. He has the same board as you (Darfon V144-001).

http://monitor.net.ru/forum/lcd-fuji...fo-121985.html

BTW, it appears that he replaced the bad UF4001 diode with a BY228.
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Old Dec 01, 2006, 10:45 PM
That tree again!!!!
thanhTran's Avatar
Germantown, MD, US
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Thank you Mr RC-CAM. I saw that link earlier when searching for the model number of the board, but I couldn't make up anything from the Babel fish translator other than knowing the guy has an exact board like mine. From the attached picture in that thread, I thought he was fixing some power supply problem (near the inverter board)

In my board, D5 appears to be the diode that provide the feed back from the back light lamp. I guess it measures current or voltage applied to the lamp. I compare the resistant of that diode with other similar diodes, which should have same function, and find that they are not different from each other.

Unfortunately, I was measuring some voltage on one of the FET gate, and the tip of the probe slipped and shorted one of its pins to another. It doesn't come up any more. I'm afraid I've killed it completely. Maybe the main chip is now dead. Looks like our house will have no TV for a while.

I called the manufacture again today, but again, customer service has no one picked up the phone. Strange!

Thanks for your help.

Thanh
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Old Dec 01, 2006, 11:51 PM
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Sorry to hear about the probe slip. That is very sad. Beyond praying, I would check the little fuse (F1, SMT part in first photo) to see if it blew.
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Old Dec 02, 2006, 10:49 AM
York Electronics
Gary Warner's Avatar
Dallas Tx USA
Joined Apr 1999
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Quote:
Originally Posted by thanhTran
I called the manufacture again today, but again, customer service has no one picked up the phone. Strange!
Thanh
Time is money in the repair business. Now you know why we don't like these things from china. They have no concept of what customer service means.

I'm asked what seems like 100 times a day "What brand of TV should I buy?Ē My answer, stick with the major Japan manufactures like Sony, JVC, Hitachi, Mitsubishi, Toshiba, Panasonic and Samsung. They are much easier to get parts and support. Stay away from odd and resurrected name brands. Most all are China or Taiwan made with little if any service support.

The sad truth though is that way too many of these cheap tvs or on the market and people donít realize that they are spending $1000+ for something that has to be thrown away in 3-5 years. Tvs that last 20 years are just about gone now.
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Old Dec 02, 2006, 12:39 PM
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Rochester, MN
Joined Jul 2003
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Quote:
Originally Posted by Gary Warner
Time is money in the repair business. Now you know why we don't like these things from china. They have no concept of what customer service means.

I'm asked what seems like 100 times a day "What brand of TV should I buy?Ē My answer, stick with the major Japan manufactures like Sony, JVC, Hitachi, Mitsubishi, Toshiba, Panasonic and Samsung. They are much easier to get parts and support. Stay away from odd and resurrected name brands. Most all are China or Taiwan made with little if any service support.

The sad truth though is that way too many of these cheap tvs or on the market and people donít realize that they are spending $1000+ for something that has to be thrown away in 3-5 years. Tvs that last 20 years are just about gone now.
Mine isn't I agree though, that there is no incentive for manufacturers to make products that last. I have a Mitsubishi TV that I bought 24 years ago (1982) and it still works great. My problem is that I can't get myself to replace things like that with anything newer until they actually fail. So no Digital/HD/PIP... for me. But probably just as well.

Mike
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Old Dec 03, 2006, 03:33 AM
That tree again!!!!
thanhTran's Avatar
Germantown, MD, US
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Quote:
Originally Posted by Gary Warner
...
The sad truth though is that way too many of these cheap tvs or on the market and people donít realize that they are spending $1000+ for something that has to be thrown away in 3-5 years. Tvs that last 20 years are just about gone now.
Another bad thing is that I told my wife before when buying that TV was that LCD TV supposed to last very long compared to standard TV, plasma, or even DLP / LCD projection TV. It's just 2 years old now. I paid $1000 for it. In 2 years, it costed me almost $1.50 a day for watching TV

Thanh
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Old Dec 03, 2006, 09:33 AM
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Wyke, Bradford, west yorks
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Quote:
almost $1.50 a day for watching TV
In the UK you need a licence to possess a TV, costs about 80cents a day, no licence and its a $1500 fine.
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Old Dec 03, 2006, 11:46 AM
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Solihull, England
Joined Jun 2004
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I think you will find that in the UK you DO NOT need a licence to own a TV only to watch broadcasts. There are some interesting issues about watching broadband TV which under many circumstances does noit require a licence.

Peter
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Old Dec 03, 2006, 12:00 PM
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If you use a TV or any other device to receive or record TV programmes (for example, a VCR, set-top box, DVD recorder or PC with a broadcast card) - you need a TV Licence. You are required by law to have one.


http://www.tvlicensing.co.uk/informa...ndex.jsp#link1.....
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Old Dec 03, 2006, 02:41 PM
That tree again!!!!
thanhTran's Avatar
Germantown, MD, US
Joined Sep 2004
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Quote:
Originally Posted by Mr.RC-CAM
Sorry to hear about the probe slip. That is very sad. Beyond praying, I would check the little fuse (F1, SMT part in first photo) to see if it blew.
Thanks Mr.RC-CAM. It's sad when the thoudsand-dollar TV is not usable because of some couple-dollar parts.

I found lcdrepair.net while searching around. They said they can fix the board for $66 flat rate if there is no fried transformer. So I will give it a try.

One option I'm thinking of if I cannot fix this back light issue is that I may play with bunch of LED's shining on the back. Not sure if LED can provide enough brightness or how much spacing I need between LED . Maybe it will look funny hehe . Currently, there are 8 lamps sitting evenly and horizontally across the back of the LCD.

Hopefully there is enough space on the back (I couldn't look at it yet because the current back light is shield.

Wow, it's sure expensive to live in UK. I wonder if I own a sling box, a DVD recorder, but I'm using for my own personal and not broadcast anything, would I have to pay liscense?


Thanh
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Old Dec 03, 2006, 03:37 PM
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Originally Posted by thanhTran
Wow, it's sure expensive to live in UK. I wonder if I own a sling box, a DVD recorder, but I'm using for my own personal and not broadcast anything, would I have to pay liscense?


Thanh
than....dont go there...........
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Old Dec 04, 2006, 11:39 AM
York Electronics
Gary Warner's Avatar
Dallas Tx USA
Joined Apr 1999
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Originally Posted by mike50
I have a Mitsubishi TV that I bought 24 years ago (1982) and it still works great.
Ah, the good old days...

When that tv starts to get a vertical foldover on the top of the picture, change the 100uf x 100volt (or it might be 50 volts) next to the vertical output transistors. It will usualy be domed up on top.
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