Temperature of CCFL transformer in laptop?

Which make and model laptop? Several Apples (my wife's for example) have issues with the backlight staying on...

John :-#)#

It's an old Dell Inspiron 1000. Only used for web, movie lists, kitchen recipes and a little personal email, nothing sensitive.

Maybe re-seating the connectors was the trick. Hopefully. I was just very surprised how hot the ferrite gets.

It may be that the CCFL is getting old, the working voltage increases over time until the inverter cannot deliver it anymore. Then the tube starts flickering or has trouble to ignite at low temperature.

Replacement tubes (and inverters) can easily be found on internet.

CCFL LCD inverters get warm, but not so hot that you can't keep your finger on the xformer[1]. When it overheats like that, I'm told that it's usually shorted turns on the transformer winding. The reason I said "I'm told" is that I've never investigated the problem and prefer to just replace the LCD inverter with whatever I can find on eBay. However, a shorted turn isn't the only thing that can heat up the xformer. An CCFL tube that's about to die will also cause overheating. You can generally spot those by just looking at the color. If it comes on initially as sorta a red-white color, instead of a solid white color, it's either a bad CCFL tube, bad inverter, or both. I check this by replacing the CCFL lamp with an external test lamp. If it lights instantly to bright white, the inverter is ok. You can also power the LCD panel with an external inverter so check the CCFL lamp. (Troubleshooting by substitution).

The Dell Inspiron 1000 is an ancient laptop. The LCD inverter is common, cheap, and easily replaced.

Might be but it starts immediately, never flickers and no weird hues.

I looked carefully for hue and tint towards the red or purple but nothing, it's nice and white. This laptop isn't used a lot so I'd be surprised if the backlights were already exhausted.

I had to replace the power cord though.

Those are the wrong ones. The correct ones are only available used:

Oh, I did as well. Designed a board for an optical switch which needed a few hundred volts. Put on the warning on English and Spanish. Guess who got bitten? Me, by my own design. A Chinese engineer could not stop laughing, "Should have had the warning on there also in German and Chinese".

Ferrite often runs at 80-100C where there's a slight core loss minima.

Fingers that burn at 50C are a poor judge of hardware that can operate at

Tim

Pretty much. Minimising weight for maximised performance is the name of the game so long as they don't cut it so fine that the thing fails.

Laptops tend to trade weight for heat provided that no external parts can ever get beyond acceptable temperatures. That said I recall some high end Pentium 3 machines tended to cook peoples thighs and sensitive bits if they were actually used in their laps. Mine of that era visibly scarred a varnished desk after a couple of years in the same place.

The one that really horrified me when I moved out of Belgium was the PSU for the cable TV & internet which was too mad hot to touch at all and had charred its ratings label to an interesting shade of medium brown.

Martin Brown

Ha, I just measured the top side of my ziggo cable modem: 69 degrees C! You can burn your fingers on that, and that is while it is doing nothing. Glad to get rid of it, will save on the 'trickety bill.

Shouldn't trust your finger for temp readings of HV magnetics. What feels like burning may be low capacitive current.

IR thermometers are pretty cheap.

RL

legg wrote in news: snipped-for-privacy@4ax.com:

always

so

heats

So are LED backlit laptops. SHEESH!

Ok, then I assume it's normal and wait until it really fails.

Sounds like Chinese engineering :-)

It was right after turning off and on a shield.

I have one but it won't measure correctly because of the reflective shielding that's glued on and next to impossible to remove.

Right, we just throw everything away at the slightest hiccup and buy new.

Joerg wrote in news:g0n1voFnfivU3 @mid.individual.net:

Let's put it this way...

Your OLD crap laptop with an fluoro backlight is old enough that the productivity time lost makes replacing it with even a friggin Chromebook a better idea.

Here's one for ya... At your place... YOU are the hiccup.

Paint the shield black or use a piece of black tape that you have tested for emissivity.

Well, I closed it all back up and called it a day. So far it hasn't failed again after reseating the connectors. Which is really weird because the backlight always started up again when hitting the power button for hibernate.

... and I measured the supply voltage to the CCFL inverter. It is always

DecadentLinuxUserNumeroUno wrote

So.. I am watching your writing on a Samsung Syncmaster 206BW that I bought in 2007, it has CFl backlight. I like the colors much better than the LED one I bought later. It was repaired once under guarantee for some strange color fault nothing to do wit hCFL), and once I replaced the power supply electrolytics.

It is not how old something is but the quality that counts. I have good electronics that is much older than that. radio tranceivers for example... Even still have an old VHS VCR in the attic, a real CRT monitor, older radios, all working just fine. Speakers, amplifiers, ANALOG SCOPE from early 1980, old cellphones... one of the first eeePCs, portable CD player.., walkman, etc