Just shake your head the same way, so you can view it normally.
OH, I'M JUST KIDDIN'!
Means to me there is a problem with the Video Cable.
The Video Cable plugs into the motherboard; under the Power Board Cover, and routes up under the Left Hinge.
[Power Board Cover = Switch Cover. The thin plastic strip under the LCD screen, and above the Keyboard. Has Power On Button in it, etc ]
From there it goes up into the Display Assembly.
It then connects to the screen Inverter, and back of LCD screen.
Example of said Video Cable for Acer Aspire 4520 Notebook PC,http://www.ebay.com/itm/Acer-Aspire-4320-4520-4520G-4720-4720G-4720Z-laptop-LCD-cable-DD0Z01LC000-NEW-/270971190515?pt=US_Laptop_Screens_LCD_Panels&hash=item3f17243cf3
In the photo the top small white plug connector, plugs into the web camera.
The larger, longer white plug connector below it, plugs into the back of the LCD screen.
The large white connector at the bottom/right, with the black band on it; plugs into the motherboard.
The smaller white plug connector pointing at the bottom; plugs into the screen Inverter.
The screen Inverter is a small long circuit board, and is mounted behind the Display Bezel; and mounted to the bottom of the LCD Screen Frame.
[The thin plastic 'frame' in front of the LCD screen; is the Display Bezel.
The LCD screen is actually an assembly. It is held together by a metal Screen Frame, that sort of resembles a metal thin picture frame ]
Due to just normal opening, and closing of the laptop; the Video Cable may become pinched, and pulled on.
This may result in loose connections of the Video Cable.
Usually loose at the motherboard connection, and/or back of LCD screen. MAY include loose connection at screen Inverter.
A simple visual inspection, will NOT reveal a loose connection.
The connections need to be Physically checked. In otherwords try to manually plug in tighter.
The Video Cable could also be damaged. Visually inspect the sheath of the Video Cable, and see if there is any apparent damage.
If so there may be Stretched/Broken wires in the Video Cable.
However, the diagnosis CANNOT go on without knowing for sure; if the Video Cable is in good repair.
1) To perform a continuity check with a multimeter, on all wires in the Video Cable. (OHM's - 1K)
Take the Video Cable to the nearest small computer repair shop; and have it tested for continuity; for a few bucks.
(Larger shops tend to badger you to have them repair it; or buy a new laptop. Yeah, right)
Due to the low cost you may simply decide to replace the Video Cable. (10 bucks plus shipping, and tax)
'Parts changing' I know, but you have to work with what you've got.
Basic example of screen Inverter,http://battery-adapter.com/product_info.php/products_id/3771/vAspire+4520+Series
Primer before I go on;
An LCD screen cannot produce light,http://solutions.3m.com/wps/portal/3M/en_US/NA_Optical/Systems/BehindTheScenes/Optics101/
X out the Feedback, click on the monitor icon.
An LCD screen needs an additional source of light.
A Backlight is the additional source.
A Backlight can be a CCFL, (Or two of them), or a series of LED's.
(Light Emitting Diode)
According to searches, the Aspire 4520 uses a single CCFL for a Backlight.
One search results,http://www.screentekinc.com/Acer__Aspire__4520_Series-series-laptops-lcd-screens.shtml
A CCFL is a Cold Cathode Fluorescent Lamp.
Similar to Fluorescent lighting used in homes, and businesses, but on a MUCH smaller scale.
Average thickness is 2mm. That is a little larger than 1/16th of an Inch.
Average length is almost as long, as the LCD screen is in height.
General example of a CCFL,http://www.laptoprepair101.com/laptop/2007/12/09/replace-laptop-backlight-ccfl-lamp/
View the last 8 photos.
A screen Inverter is used to convert the power, (Electricity), from the laptop; for the LCD screen, and Backlight.
Note* Notebooks using LED's as a Backlight; do not use a screen Inverter.
ALL power removed. Remove the AC adapter (Charger), and Battery.
Follow removing the screws circled in Red.
The Latches indicated in Green, are GENTLY depressed with a flat tipped screwdriver. Use a small flat tip, be GENTLE. You can break those plastic latches.
The Philips head screws, and those Latches; hold the Switch Cover (Power Button Cover), on.
In the 3rd photo down, the Video Cable connection to motherboard, is shown in the Orange box to the Left.
I'm also going to include a link to a free Service Manual, so this will become all too clear. (Photos are less than, but though they may help too)
Posting pictorial information now, with the desire it may help you to SEE how to perform, these procedures;
On the Aspire 4520 there are FOUR rubber screw covers, going across the top. I use a computer pick to gently raise one side, of the rubber cover, and then pick it off with fingers, and thumb.
They are held on by a type of rubber cement; and if careful with them, you may be able to reuse. If not just apply a tiny dab of rubber cement, and stick them back on. (I use a toothpick dab)
(I also stick them along the Display Bezel, for safekeeping until reusing )
There are TWO Philips head screws to remove from the bottom.
One in each corner.
Once the screw covers are removed, and the screws; the Display Bezel is flexed, and removed.
The Display Bezel has Tabs, going around the inside edge of it's outside perimeter.
These snap into Latches in the Display Cover. (Top Cover)
The procedure is to lay the Display Assembly back as far as you can, and cover with a soft piece of cloth. Protect the LCD screen from your fingernails when removing Display Bezel.
I cut a cereal box to fit the inside edges, of the Display Bezel.
(Some techs use computer gloves )
I find if you go to the left side/middle of the Display Bezel, and gently lift up with your fingertips; then move along with your fingertips under the bezel, and lifting it; the Bezel will flex, and start to pop off.
Snap, snap, snap. The Tabs/Latches start releasing. You have to use care not to break the Bezel, but it's pretty tough stuff.
Work up to the top corner, then down to the bottom corner; using your fingertips under the Display Bezel.
When this side is mostly loose, start working on the top left corner.
Now go to the bottom.
Work across from left side to right side.
This pictorial details a little more of what I'm 'talking' about,http://www.insidemylaptop.com/how-to-replace-screen-on-dell-inspiron-n4010-laptop/
I don't see that this laptop has a Latch at the Top/Middle. If it did, when the Display Bezel is loose, you would have to slide the Display Bezel to one side, and clear that Latch.
Display Bezel off you have access to the mounting screws, holding the LCD screen TO Display Cover.
Two in each lower corner. (All screws noted in this solution, are Philips head screws )
Remove the mounting screw at top for Web Cam.
This should now, allow you to tilt the top of the LCD screen forward, and check the Video Cable TO LCD screen connection.
You can also check the screen Inverter cable connections, (2)
After checking that the Video Cable TO motherboard connection, is tight, (Physically check), and the Video Cable TO LCD screen is tight; I would leave the LCD screen like it is, plug the Battery back in, and AC adapter.
Power the laptop on, and see if loose connections of Video Cable, is the problem.
Then suggest test, or have tested; the Video Cable, for continuity.
OR replace the Video Cable.
Happens. Means you will be out bucks for having the Video Cable checked, or replaced.
If this occurs replace the screen Inverter.
[Screen Inverter checking requires a sensitive multimeter. Read fairy expensive,http://www.fonerbooks.com/test.htm
Due to the ease of access, and low cost of screen Inverter; those who do not have access to a sensitive multimeter, usually just replace the screen Inverter. This IS parts changing I know. Sometimes though you just have to work with what you have.
Otherwise it means dragging a partially disassembled laptop down to the computer repair shop, and having a tech check it.
Very few know about using a sensitive multimeter to check, and you'll probably get a 'deer in the headlights look'.
Also they will want to repair the laptop. This = No IMHO.
Save money, and do it yourself ]
Link to free Service Manual,http://www.tim.id.au/blog/tims-laptop-service-manuals/#toc-acer
Go to the 'paragraph' that starts with Aspire 1200. (1200 in Blue)
Drop down to the 4th line. (3810T in Blue)
Scroll across, and click on the blue -> 4520
Ignore if you are aware;
This is a PDF file. The computer you are using now has Adobe Reader on it. which uses PDF files.
After you click on the file name (4520), it may take up to 30 seconds, before the first page comes up.
The PDF file is downloading in the background, and will not show until the full file is downloaded.
This is a Temporary download. If you wish to save a copy to disk, or flashdrive; there is a method. Post in a Comment if you would like to know.
Have a stupid question?
To me there is NO such thing. Post whatever question you have in a Comment. (Or questions)
[I know the above procedures may seem daunting, and you may feel it is beyond your scope. I think differently. If you played with Lego's, or blocks as a child; you can do this. (That, and turn a screwdriver, lol! ]