What fails in CCFL inverters?

Started by John E. April 26, 2009
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

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
"John E." <incognito@xbjcd.com> wrote in message
news:0001HW.C6194C9E007788DCB02149AF@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
On Apr 26, 8:26=A0am, John E. <incogn...@xbjcd.com> wrote:
> What fails most commonly in inverter circuits in, for example, 18 inch LC=
D
> 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
"John E." <incognito@xbjcd.com> wrote in message 
news:0001HW.C6194C9E007788DCB02149AF@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.
> 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
Thanks, guys. 

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

"John E." <incognito@xbjcd.com> wrote in message 
news:0001HW.C619CDF80095D9B4B02149AF@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.
> 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
On Sat, 25 Apr 2009 23:26:22 -0700, John E. <incognito@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 jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558