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design | What fails in CCFL inverters?


There are 42 messages in this thread.

You are currently looking at messages 1 to 10.

What fails in CCFL inverters? - John E. - 2009-04-26 02:26:00

What fails most commonly in inverter circuits in, for example, 18 inch LCD 
displays? 

<http://www.lcdrepair.us/1800inverterKUBNKM045A.html>

I know anything *can* fail. But is there a common, high-frequency failure 
component in these inverters?

Thanks.
-- 
John English


Re: What fails in CCFL inverters? - don - 2009-04-26 08:10:00

John E. wrote:
> What fails most commonly in inverter circuits in, for example, 18 inch LCD 
> displays? 
> 
> <http://www.lcdrepair.us/1800inverterKUBNKM045A.html>
> 
> I know anything *can* fail. But is there a common, high-frequency failure 
> component in these inverters?
> 
> Thanks.
In the inverter that I have replaced, I have seen the inductors burned 
up or open.

So I would say that the inductor insulation got hot and shorted between 
windings.

don

Re: What fails in CCFL inverters? - Vladimir Vassilevsky - 2009-04-26 09:10:00

"John E." <i...@xbjcd.com> wrote in message
news:0...@news.sf.sbcglobal.net...
> What fails most commonly in inverter circuits in, for example, 18 inch LCD
> displays?
>
> <http://www.lcdrepair.us/1800inverterKUBNKM045A.html>
>
> I know anything *can* fail. But is there a common, high-frequency failure
> component in these inverters?

The short between the turns of the transformer is a very common failure.

VLV








Re: What fails in CCFL inverters? - 2009-04-26 09:26:00

On Apr 26, 8:26 am, John E. <incogn...@xbjcd.com> wrote:
> What fails most commonly in inverter circuits in, for example, 18 inch LCD
> displays?
>
> <http://www.lcdrepair.us/1800inverterKUBNKM045A.html>
>
> I know anything *can* fail. But is there a common, high-frequency failure
> component in these inverters?
>
> Thanks.

It is mostly the TV programs that fail.

> --
> John English


Re: What fails in CCFL inverters? - Lynn - 2009-04-26 11:33:00

"John E." <i...@xbjcd.com> wrote in message 
news:0...@news.sf.sbcglobal.net...
> What fails most commonly in inverter circuits in, for example, 18 inch LCD
> displays?
>

the same thing that fails in 15 inch LCD displays. 



Re: What fails in CCFL inverters? - John E. - 2009-04-26 11:36:00

> It is mostly the TV programs that fail.

Very funny. I agree: My TV won't survive another episode of "Lost". 

But that's a discussion for another time...
-- 
John English


Re: What fails in CCFL inverters? - John E. - 2009-04-26 11:38:00

Thanks, guys. 

So it looks like they're unrepairable. I'll order one of the replacements. 
-- 
John English


Re: What fails in CCFL inverters? - Lynn - 2009-04-26 11:46:00

"John E." <i...@xbjcd.com> wrote in message 
news:0...@news.sf.sbcglobal.net...
> Thanks, guys.
>
> So it looks like they're unrepairable. I'll order one of the replacements.
> -- 
> John English
>

nothing's unrepairable. 



Re: What fails in CCFL inverters? - John E. - 2009-04-26 12:43:00

> nothing's unrepairable. 

Agreed. But "practicably", cost-effectively, this one is not worth it. 

If this was a 60" Panasonic that only needed one inductor wound, and a new 
PDB was not available, I'd probably think differently.
-- 
John English


Re: What fails in CCFL inverters? - Jeff Liebermann - 2009-04-26 12:44:00

On Sat, 25 Apr 2009 23:26:22 -0700, John E. <i...@xbjcd.com>
wrote:

>What fails most commonly in inverter circuits in, for example, 18 inch LCD 
>displays? 
>
><http://www.lcdrepair.us/1800inverterKUBNKM045A.html>
>
>I know anything *can* fail. But is there a common, high-frequency failure 
>component in these inverters?

The transformer seems to be the most common problem.  I've only tried
to repair about 4 of these.  Three were visibly (under a microsocope)
burned and probably shorted when the insulation melted between turns.
One was open.  All were repaired by replacing the transformer (usually
cannibalized from a similar LCD inverter).  

I've also seen a few with fried switching transistors.  However, those
were probalby the result of a shorted transformer.

Only once have I seen a dead CCFL tube (that wasn't broken by whomever
tried to repair it previously).

At this time, I don't consider it worth the time and effort to repair
the inverters.  I might if I can't obtain a pull-out repacement on
eBay or if the LCD inverter circuitry was built onto the main driver
board, as is common on many LCD computah monitors.  

Incidentally, I've been tempted to slop some thermally conductive
epoxy on the xformer in order to improve the heat dissipation.
However, without an IR camera, and more spare time, I haven't
bothered.


-- 
Jeff Liebermann     j...@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558

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