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Old 09-10-2011, 03:51 PM   #1
gorr35
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Default Bypass LCD TV Inverter Board Shutdown Backlight?

"How To Bypass LCD TV Inverter Board Shutdown Backlight System" Has anyone seen this article before (Below)? Has anyone tried it? Sounds pretty dangerous to me. Supposedly it is to check to see if your CCFL Lamps are out when you get sound but no picture, or if it's the inverter board itself. Do all LCD TV's have a similar chip with the same functions?

http://www.bestelectronicarticles.co...ht-system.html

Last edited by gorr35; 09-10-2011 at 04:06 PM..
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Old 09-10-2011, 05:22 PM   #2
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Default Re: Bypass LCD TV Inverter Board Shutdown Backlight?

I think it could easily damage a transformer or driver FET if the CCFL is shorted or open, due to either high currents on the primary, or high voltages (due to lack of load.) Maybe...
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Old 09-10-2011, 05:30 PM   #3
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Default Re: Bypass LCD TV Inverter Board Shutdown Backlight?

It won't short any FETs because the controller's also got got current sense... but yes it could damage a transformer by arcing if the CCFL is open. Best bet is still testing the CCFLs with a spare board.
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Old 09-10-2011, 09:06 PM   #4
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Default Re: Bypass LCD TV Inverter Board Shutdown Backlight?

could this problem cause a strobe effect for about 10 or 15 minutes and then go away? In other words, my Vizio VX42L strobes the screen for about that long, then the screen straightens out and looks great. I was told that the CFFL was failing and the only repair was to replace the extremely expensive LCD screen. Does that sound right?
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Old 09-10-2011, 10:28 PM   #5
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Default Re: Bypass LCD TV Inverter Board Shutdown Backlight?

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Originally Posted by Jrolfe View Post
could this problem cause a strobe effect for about 10 or 15 minutes and then go away? In other words, my Vizio VX42L strobes the screen for about that long, then the screen straightens out and looks great. I was told that the CFFL was failing and the only repair was to replace the extremely expensive LCD screen. Does that sound right?
Thanks,
Jeff
That sounds like someone wanted to take an 'unrepairable' TV off your hands cheap. Well, let me be correct. A service shop affiliated with the manufacturer may have no choice except to replace the LCD panel (which usually includes the CCFLS and the inverter).

I would suspect a capacitor, but I haven't dug into the workings of the inverters Vizio uses.

Here is a quick background. Every inverter I have seen uses an 'inverter controller' to provide a stable output, and provide safety features in case of an aging or broken CCFL. I have not performed an exhaustive review, but in every case I have researched, if a problem 'trips' the protection, the inverter shuts down and stays down until reset.

Next, there is the fact that 'strobes' is ambiguous. I tend to think of a strobe light used to freeze motion. This turns off completely. IF the panel on your TV is flickering (getting brighter, then dimmer, but always staying on), yes a bad CCFL could be causing that. It IS common with a CCFL failing due to age or a defect. As I said above, it can also be caused by a bad capacitor.

There are many different layouts for LCD displays, but in general, while the manufacturer says they are unrepairable, the fact is CCFLs are replaceable by anyone with decent mechanical skills.

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