Flickering Screen on Toshiba Equium A300D-16C

I have a Toshiba Equium A300D-16C which I am looking at for a friend. It had multiple problems, such as battery not charging, overheating, and screen flickering. I have managed to resolve the overheating (fluff in the fan & no thermal paste on the CPU) and fixed the battery charge issue with a BIOS update.

However the screen still flickers intermittently (see video Flickering Screen), with lots of horizontal lines going up and down the screen. Sometimes this can happen straight from boot, sometimes it can happen after it’s been on for an hour or so. Pressing on the back of the screen can improve the problem, but usually it takes a shutdown and reboot then it may come back up OK, or might come back up still with the flickering lines, and take 3 or 4 reboots, or leaving it off for 15 minutes.

I’d like to try and get it fixed, and think it’s either the inverter, the LCD screen cable, or possibly the display. Before I go buying a load of unnecessary replacement parts from eBay, can anyone tell from the video posted, which it’s more likely to be, cable, inverter or screen?
bjblackmoreAsked:
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hunartCommented:
I still believe this issue is directly related to the inverter.  If the video chip fried, I don't believe that there will be any display.
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hunartCommented:
The first thing you should do is check the refresh rate within Windows and make sure that it is set at 60Mhz.  That should work with most monitor.  Get the correct and latest video driver for the laptop as this could cause problem too.

If the above does not fix the problem, it is more likely that the inverter/back light is the problem.  If you do not have the experience opening the LCD panel and replace the inverter board, please have it replaced by a shop as it would cost much to replace it.
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sjklein42Commented:
It is not the backlight.  The flickering you are seeing is loss of synch and is symptomatic of an overheating video chip.  Normally on a laptop you do not have control over the refresh rate.

If you connect an external monitor, you can determine if the problem is the video chip (which would affect the external as well as internal) or is the display itself.

If it is the display, you may be able to fix it by simply reconnecting the ribbon cable.  Before replacing the display, it is always worth removing and then reinstalling it.
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nobusCommented:
imo - the overheating laptop damaged the video card; you can always test if the flickering exists also if booted from a live cd  : ftp://ftp.gwdg.de/pub/linux/knoppix/KNOPPIX_V6.7.0CD-2011-08-01-EN.iso 
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bjblackmoreAuthor Commented:
Thanks for the replies.

I don't believe that it is the refresh rate or video driver, as this happens from boot during the POST, which is before Windows has loaded any drivers.

I will try an external monitor, if I can find a VGA one (I only have a DVI monitor at home), and see what the output is like.

I thought it might have been an issue caused by the overheating, but hoped that as it was an intermittent issue, it wasn’t permanently damaged, especially if it’s the video chip, as it’s built into the motherboard, so can’t be replaced/repaired.
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JRoyseCommented:
If the video chip can't be cooled better and the display cable isn't loose on the mainboard (or frayed) You could think about buying another used laptop off ebay perhaps with a broken screen and use it's mainboard.  I don't always have trust in video chips once they have overheated.  It is my opinion, and i have seen it twice once they go in a laptop they'll be that way or get worse.
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bjblackmoreAuthor Commented:
I have just found a VGA cable, and connected it to the VGA port on my external monitor (didn't realise it had VGA & DVI), and booted the laptop, and the external monitor is displaying OK, but then again, currently so is the laptop monitor, so I'm going to leave it on and see how it runs over the next hour or two.

I do have some thermal transfer paste, which I could use between the video chip & heatsink - the heatsink is one of those complex designed ones, that sit on the CPU, then has a bar that comes out, sits on top of the video card, then dends into the fan outlet (CPU/VGA Heatsink), this may help cool the video card down a bit more.

Am I correct in thinking that if the laptop screen starts to flicker, but the external monitor is OK, this would point to the inverter rather than video chip? I'm guessing that if the laptop hasn't moved, and has been on test sat in the same place when the flickering happens it's less likely to be the display ribbon cable, as it should only have an issue if the laptop is being moved or the lid opened closed, it's not going to move on it's own!?
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nobusCommented:
you can test it with Knoppix, as said
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nobusCommented:
<<  this would point to the inverter rather than video chip?   <<  there is no inverter afaik  - so it should be the video chip
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bjblackmoreAuthor Commented:
Following the answers above, I test the laptops for the following 2 weeks, turning it on, leaving it for several hours, then rebooting, shutting down, closing the lid, etc, but could not get the flicker to represent itself, so it was difficult to diagnose further!
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