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Flickering white lines

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June 26, 2011 1:08:26 PM

Hi There, I just got a Presario C500 with broken left hinge and display prob. Display is grey with thin red pink, sometimes green and thick white lines top to bottom (one of each). Top third of screen has changing white horizontal lines. Replaced hinge and screen cable, still the same, looked at plug pins with a magnifying glass, all pins OK. Works fine on external screeen, I guess it's LCD or GPU. How can I be sure?

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a b D Laptop
June 27, 2011 5:30:44 AM

niloc45 said:
Works fine on external screeen,


That's how you be sure. If output is good on an external, the LCD is to blame. Replace it and smile!
:D 
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June 28, 2011 8:02:47 PM

frozenlead said:
That's how you be sure. If output is good on an external, the LCD is to blame. Replace it and smile!
:D 

wow...
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July 6, 2011 8:49:59 AM

Yup screen is defective but there's 2 faults. Already tried replacing screen, still doesn't work, get variations in brightness on 'new' screen, no lines down or across but no image ('new' screen works fine on other laptop and is compatible LP154W01). Changed ribbon cable also without improvement, I'm 90% sure there's a solder break on the GPU on one or more of the data lines. Awaiting new MB. The LCD is defective I think because someone may have thumped the screen to try and clear the flicker (not me, honest!). It seems to be routine to get broken screens with GPU faults, human nature being what it is!
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a b D Laptop
July 7, 2011 3:13:04 AM

Try hooking up an external monitor thru VGA. If it doesn't work, it is indeed your GPU. If it does work... well, there are more possibilities to investigate.
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July 9, 2011 7:53:15 AM

It works fine on a PC external screen, that was the first (and most obvious) thing I tried. But (via VGA) on my Panasonic TV it does give a dim and odd coloured picture as compared to using an LCD PC monitor which as I said is fine. Ridiculously must've spent around 100 hours on this (on and off) hampered by not having another C500 to steal parts off. If a 'new' MB solves it, I'll post the good news here. I still think it's a BGA reball job.
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a b D Laptop
July 9, 2011 4:49:39 PM

If the machine works fine on an external screen, does not on your TV, and the two used the same connection, logic implies that your TV is to blame. However, the other new monitor you bought didn't work you said - did it show the same kind of image the TV did?

You can put a heat gun to your GPU without harming it, so try that if you've got one.
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July 9, 2011 5:41:04 PM

I've used my TV's VGA connection for 5 or 6 different laptops I've had with no problem (apart from aspect ratio errors), so I think it's significant it only 'played up' with the C500- the image was dim with a colour cast (even on bios). With the 'ordinary' PC type monitor the image was fine though, in all modes. No LCD screen put in the laptop worked properly, only giving brightness differences without any image detail (I tried 3), the original flickering white lines are gone. I've got a heat gun, but I'm waiting for a replacement motherboard to try. I don't know why there's been suggestions that if a laptop gives an image on an external screen then the GPU/motherboard are O.K., that simply isn't the case, even with my limited knowledge I know otherwise! Thanks for your help.
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July 21, 2011 1:17:29 PM

The problem is now fixed!!!!! I fitted a new motherboard and onboard screen outputs are fine now. I surmise the GPU had bad connections to it, as I thought, despite those who disbelieved me! The original screen still doesn't work of course, giving several coloured lines only again. Thank-you for all your comments and help. I was unlucky enough to have an LCD screen failing together with the GPU problems also worsening. To those that say if an external screen works the GPU is O.K., I say 'toffee'!
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July 21, 2011 1:19:01 PM

Best answer selected by niloc45.
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