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PC-Man
06-29-2011, 08:32 PM
A customer called regarding a problem with his sony vaio laptop about 2 years old model: VPCCW25FG. The screen is very dim can hardly see desktop icons. I pickup the laptop, told the customer that the problem could be LCD inverter and I gave him a quote for an inverter replacement as I have fixed many lcd problems with similar symtoms in the past.

Before ordering any parts I opened the screen and I could not find any inverter, it turns out that the screen is an LED screen. I removed the screen to locate the part number "LP140WH2 TL N1 ", and I found one on ebay. I called the customer to inform him that the screen need replacing as there is no inverter. The customer gave a go ahead. I ordered the screen, arrived today, installed the new screen I got the same result as the old one. Dim background. I have connected external monitor to the laptop no problem everything works ok.

Getting confused, could it be as I received DOA lcd? tired of all these sony vaio laptops.

I welcome your input please. Thanks for reading.

phaZed
06-29-2011, 09:52 PM
I would guess that there may be something wrong with the VGA cable. Perhaps the signal wire to the LED controller is broken or not making contact. Have you checked the VGA cable connector on the motherboard?

The LED backlight is controlled by non other than an LED backlight controller, usually integrated onto the mobo. Here's a standalone version:
http://www.generaldigital.com/products/led_backlights/datasheets/led_backlight_controller_ds.pdf

It used PWM (Pulse width modulation) to blink the LEDs at a slower/faster rate to give the illusion of varying brightnesses. If the signal wire to the controller is "broken" then the controller may be defaulting to the "dim" setting you see.

Just a guess.

PC-Man
06-29-2011, 10:08 PM
I would guess that there may be something wrong with the VGA cable. Perhaps the signal wire to the LED controller is broken or not making contact. Have you checked the VGA cable connector on the motherboard?

The LED backlight is controlled by non other than an LED backlight controller, usually integrated onto the mobo. Here's a standalone version:
http://www.generaldigital.com/products/led_backlights/datasheets/led_backlight_controller_ds.pdf

It used PWM (Pulse width modulation) to blink the LEDs at a slower/faster rate to give the illusion of varying brightnesses. If the signal wire to the controller is "broken" then the controller may be defaulting to the "dim" setting you see.

Just a guess.

Thanks for your response, I have reseat the cable on the motherboard. The connectors seems to be intact.

phaZed
06-29-2011, 10:37 PM
Thanks for your response, I have reseat the cable on the motherboard. The connectors seems to be intact.

Well, in that case I would try one more LCD, and return the one you got. If you are still having the problem with a 3rd LCD then I would chalk it up to a bad motherboard. Possibly the MOBO isn't correctly "talking" to the LED controller or there is a voltage/current supply problem to the LED's via the MOBO.

Odd problem to have, sorry you got it :eek:

PC-Man
06-29-2011, 10:46 PM
Well, in that case I would try one more LCD, and return the one you got. If you are still having the problem with a 3rd LCD then I would chalk it up to a bad motherboard. Possibly the MOBO isn't correctly "talking" to the LED controller or there is a voltage/current supply problem to the LED's via the MOBO.

Odd problem to have, sorry you got it :eek:

Thanks, I will call the customer first to let him know what is going on, and then contact the lcd seller for eventual replacement. These things happens.

Thanks again for your input and will update of the outcome.

shamrin
06-29-2011, 11:16 PM
Buying screens off eBay can be a little hit-or-miss. And the LED screens can be sensitive down to the version number so be careful about substitutions. PM me if you want a recco for a couple of good screen suppliers.

Having said that, it seems odd that both screens are dim and behave the same way. If it were me, I'd hang on to the screen and order a new video cable instead.

mraikes
06-30-2011, 03:22 AM
I ran across a mention once about a fuse on the motherboard causing an LED screen to be dim. If so, that would account for multiple "failed" screens - with is pretty unlikely otherwise.

PC-Man
06-30-2011, 11:42 AM
Well, in that case I would try one more LCD, and return the one you got. If you are still having the problem with a 3rd LCD then I would chalk it up to a bad motherboard. Possibly the MOBO isn't correctly "talking" to the LED controller or there is a voltage/current supply problem to the LED's via the MOBO.

Odd problem to have, sorry you got it :eek:

Thanks, I have now return the lcd and the seller agreed to ship a replacement. Hopefully will get it by tomorrow and see what happens. Somebody have suggested that it could be a fuse on the motherboard, I have taken the laptop apart and could not locate any fuse.

If test the replacement screen tomorrow and still no luck, I will simply retun the laptop.

Thanks to everyone that have responded.

IAMPC
06-30-2011, 03:31 PM
The dim issue with laptop screens is not usually related to the inverter as most people believe. In most cases it is the screen itself having the problem and in rare cases either the video ribbon is bad or there is a problem with the mobo.

mraikes
06-30-2011, 04:23 PM
>>>>>>> snip <<<<<

Somebody have suggested that it could be a fuse on the motherboard, I have taken the laptop apart and could not locate any fuse.

>>>>>>>> snip >>>>>>>>>.

Found it:

http://nwapchelp.wordpress.com/2011/05/25/dim-laptop-led-f1-fuse-just-below-the-motherboard-connector/

Pc Fixed Right
06-30-2011, 05:32 PM
This might be a simpler fix. I had the exact dimming issue before. Go into the graphics properties and reset everything back to default. That may fix your issue or may not but worth a shot as it fixed the issue for me.

stevenamills
06-30-2011, 07:51 PM
Hopefully, mraikes is right about the fuse.

I had a similar problem here and I'm POSITIVE I was eventually told that there's a code or something that only Sony will do at their service centers. This was after 2 screens exhibited the same issue. I can't find the reference right now.

That sounds like something Sony would do.

PC-Man
06-30-2011, 08:24 PM
Hopefully, mraikes is right about the fuse.

I had a similar problem here and I'm POSITIVE I was eventually told that there's a code or something that only Sony will do at their service centers. This was after 2 screens exhibited the same issue. I can't find the reference right now.

That sounds like something Sony would do.

After visiting the link mraikes posted, I removed the motherboard and could not locate any fuse. (:

PC-Man
07-01-2011, 08:48 PM
Final update, received a second LCD today, same result. Motherboard problem, I have returned the laptop back to the owner. Cannot find a replacement mobo and it will be too expensive. Cheers