Backlight on laptop works sometimes.Inverter or?

  forevolution 19:51 02 Mar 2011

Hey guys, just a quick question.

Last Saturday I used my laptop and everything was fine. I packed my laptop into its bag and took a train journey home. When I got home the screen all of a sudden went off. Now Ive tried fiddling with the screen inverter and yesterday the backlight lit up for a good few hours. Thinking it must have been a loose connection I put the laptop back together again. However, its gone back off again. Its an acer aspire 5735 that i've had just short of 2 years. Pressing fn + f6 to toggle the backlight on and off the backlight will light up for a split second, sometimes maybe a few seconds before it goes back off. I do recall hearing a slight humming noise when the screen was on say 50% brightness but paid no attention to it. Do you guys think its the inverter at fault or the backlight, possibly even motherboard?? Ive really not got any tools (volt metre) so its very difficult for me to isolate. Dont really wanna get an inverter to find out its not that!!

Any ideas from anyone? What do you guys suggest?

Cheers people,

  robin_x 20:43 02 Mar 2011

My only screen problem was a cracked one. But I keep my eye open for useful bookmarks.

Hope these help.

click here

click here

  robin_x 20:46 02 Mar 2011

oh btw, I am sure you can get a multimeter these days for a tenner.

  Fruit Bat /\0/\ 21:10 02 Mar 2011

connection to inverter
sticking lid switch

  mooly 07:54 03 Mar 2011

The humming noise could be a big clue... as that's typical of any type of switching supply (which an invertor is) failing. The cause is nearly always failing capacitors.

The fact it seems intermitent means it may be worth examining the invertor under light and magnifying glass to see if there are any badly soldered/heat affected joints.

  forevolution 15:02 03 Mar 2011

Cheers for the replies guys, much appreciated. Im now almost sure its got to be the inverter. Woke up this morning and the backlights been working fine?! Definately makes it difficult to isolate when it works one minute. Ive noticed a capacitor on the inverter looks as if its melted, hence the humming sound? Ive uploaded a picture what do you guys reckon??

[URL=click here][IMG]click here[/IMG][/URL]

  mooly 18:26 03 Mar 2011

Bit hard to make out tbh but it certainly looks like something has melted. Not clear enough to see whether it is the component or something that has been in contact with it.

  br1anstorm 13:05 04 Mar 2011

I recently had - and posted about - a similar problem. Looks as if you may have identified the fault.

Other tips: if there is a pink tinge to the screen when it lights up (before going blank), then it's almost certainly a failing backlight tube (CCFL).

If there's no pink tinge, it's more likely to be the inverter.

If you shine a bright light or torch at the blank screen and can still make out a very faint outline of the screen-images, or if a good image appears on a separate plug-in monitor screen, then the video/graphics card etc is OK.

Hope this helps.

  forevolution 17:32 11 Mar 2011

Easy peeps..
Thanks for all the replies, just a bit of an update really. I purchased a new screen inverter from eBay, came in the post today. Sad to say that the problem still persists. The backlight just flickers for a fraction of a second when I press the backlight on/off switch. Really disappointed to be fair, it could only be either the backlight or the motherboard, and I think it could be the mobo. Pain in the ar*e as ive now gotta decide whether the laptops worth it...

Any other suggestions at all? Something else I could try??

Thanks people!

  mooly 18:54 11 Mar 2011

Measure the DC voltage being supplied to the invertor from the MB (not the invertor output) to see if there is a problem.

  woodchip 19:06 11 Mar 2011

Yes those have had it Reflection stopping good view but did zoom in to look at them as best I could. That is not right as can be seen, and they are not doing there job probably shorted out and letting DC through

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