Replacing LCD inverter and possibly the backlight.

Fn with ^ key? Why? The Display Toggle-Over key is the F8 key.
Fn key plus UP Arrow key is to increase the Brightness.

You hold the Fn key down, and tap once on the F8 key.

(Of course there are at least 3 display options available;
A) Laptop internal monitor ONLY.
B) Laptop internal monitor AND external display device.
C) External display device ONLY.

You may have to hold down on the Fn key again, and tap once more on the F8 key)

You switched LCD screens with a working one, and it works OK.

Reason is you also switched the screen Inverter, too. Correct?

http://www.ebay.com/itm/New-LCD-Inverter-Board-for-Dell-Vostro-1000-1500-Series-US-/280987325828?pt=US_Laptop_Screens_LCD_Panels&hash=item416c265584

The screen Inverter is mounted to an area at the bottom of the LCD screen, and behind the Display Bezel,

http://www.dell.com/support/Manuals/us/en/19/Product/vostro-1500

Click on - Service Manual (1817 KB)
It's a PDF file. The computer you are using now has Adobe Reader on it, which uses PDF files.
After you click on Service Manual, it may take up to 30 seconds, before the first page comes up.

Click on Display.

Primer:
An LCD screen does Not produce light,

http://solutions.3m.com/wps/portal/3M/en_US/NA_Optical/Systems/BehindTheScenes/Optics101/

(Click on the monitor image)

It needs an additional light source.
A Backlight is the additional light source.

A Backlight can be a CCFL, (Or two of them); Or a series of LED's.
(Light Emitting Diode)

The Dell Vostro 1500 series of Notebook PC's, uses a single CCFL for a Backlight.

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.

http://www.laptoprepair101.com/laptop/2007/12/09/replace-laptop-backlight-ccfl-lamp/

View the last 8 photos.

It is just like Fluorescent lighting used in homes, and businesses also, because it has MERCURY vapor inside.
HIGHLY toxic.

A screen Inverter is used to convert the power, (Electricity), from the laptop, for the LCD screen, and Backlight.

(NOTE* Does NOT apply to laptops that use LED backlighting.
There is NO screen Inverter used)

90 PERCENT OF THE TIME the fault is a bad screen Inverter.

Primer over.

Me? I would buy a screen Inverter, due to the low cost, and ease of accessing to replace, and replace it, and use the old LCD screen.

[ You did check Video Cable connections -> PHYSICALLY, (Try to plug in tighter), on the Video Cable motherboard side connection, LCD screen connection, and screen Inverter connection; correct?]

For additional questions, or to have me clarify anything I have stated above; please post in a Comment.

Regards,
joecoolvette

It is the screen Inverter, or the LCD screen itself.

Screen Inverter: A small circuit board located behind the Display Bezel, and mounted towards the bottom of the LCD screen,

http://support.dell.com/support/edocs/systems/vosA860/en/sm/display.htm#wp1183775

The yellowish long object, at the bottom, is the screen Inverter.

Here is another look at it,

http://www.batterycenturys.com/dell-vostro-a860-inverter-p-185294.html

Dell Support > Vostro a860 Notebook PC > Service Manual,

http://support.dell.com/support/edocs/systems/vosA860/en/sm/index.htm

In the list clicking on -> Display, will get you to the first link above.

Need guidance in replacing the screen Inverter, post in a Comment.

(Just a basic guide using a Vostro 1014/1015 Notebook PC. Not yours, but good for basic guidance. This is replacing the LCD screen,

http://www.insidemylaptop.com/replace-lcd-screen-dell-vostro-1015-1014-laptop/ )

[ Primer:
An LCD screen cannot produce light by itself,

http://solutions.3m.com/wps/portal/3M/en_US/NA_Optical/Systems/BehindTheScenes/Optics101/

( Click on the small window with the monitor in it )

It needs an additional light source. A Backlight is the additional light source.
A Backlight can be a CCFL, (or more than one), or a series of LED's used as lights.

The Dell Vostro a860 Notebook PC uses one CCFL, for a Backlight, OR there are Vostro a860's that use LED lights.
(If you replace the LCD screen, make sure FIRST of what type of Backlighting it uses)

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 of a CCFL 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 ]

A screen Inverter is used to convert the power from the laptop, for the Backlight, and LCD screen.

Most of the time the fault is the screen Inverter.

The Vostro a860 Notebook PC's, that uses LED's as a Backlight, MAY also use a screen Inverter.

Primer over.

For your problem it could be the screen Inverter, but I lean more towards the LCD screen itself, is the problem.

How to test a screen Inverter? Requires a very sensitive multimeter.
Read; Expensive,

http://www.fonerbooks.com/test.htm

For a layman who does not have access to a sensitive multimeter, the method is to just replace the screen Inverter, and see if it is the problem.
'Parts changing', I know, but if you do not have the proper equipment to test with?

Screen Inverter replaced, and problem still persists, replace the LCD screen,

http://www.laptopscreen.com/English/model/Dell/VOSTRO~A860/

For additional questions please post in a Comment.
Regards,
joecoolvette

The most common parts to go out are the backlight itself, and the cables. If possible, remove the cables from the laptop, and check for continuity with a digital multimeter (DMM). If you are getting a good connection it is the backlight. If you don't get a good connection, the cables are the problem.

You cannot replace the backlight. It is incorporated into the lcd panel and not available as a separate part. The inverter board is very easy to replace. It is located right behind the dell logo at the bottom centre of the display panel. Remove the screws on the front of the lcd bezel (under the rubber pads) and the inverter board is right there. Call 1-800-www-dell or look on ebay. Hope it's only the inverter board, as a new lcd panel is $350+. If the display is dead you can still use the laptop by connecting an external monitor to it.

Hope this helps!....let me know how you make out.

You are probably not going to like my answer but your new screen may have a bad Backlight or connection, that is what lights up the lcd panel. Check your connection at the inverter just to make sure, sometimes these connection can get reversed or get loose during the reinstall. I would take it back apart and check it from the main cable on the back all the way to the motherboard.

Dell Dell™ Vostro™ 1500 XP Windows Driver Recovery CD Restore DiskThis is an automated Dell™ Vostro™ 1500 XP drivers recovery cd. The Dell™ Vostro™ 1500 drivers are supplied in a special windows friendly format. This means that your Dell Dell™ Vostro™ 1500 XP Laptop will automatically find and install all the drivers for your system, with hardly any user intera ..... dell vostro 1500 eeprom short ...

Your unit uses a fluorescent backlight and an inverter to provide the high voltage for it. Considering that it varies in intensity, it isn't likely a failing fluorescent tube (these will mostly fail gradually and not recover) but rather the inverter and this is often a small separate board that is replaceable.

Are you good with a screwdriver? Here's a step by step procedure for replacing the LCD screen on a Dell 1500.
http://www.insidemylaptop.com/replace-damaged-lcd-screen-dell-vostro-1500-laptop/
Is fairly easy, but be extremely careful of the ribbon cables, they break very easily!
Good Luck!

It could be both. But usually it's this order:

inverter, backlight, lcd, video card, lcd cable.

I always start by checking out the inverter first since it's the easiest as well.

The cheapest place to get a replacement is eBay for sure.

Best of luck!

think you might have a failed screen inverter (FL inverter); this problem is very common with laptops. The inverter board acts as a power supply for the LCD screen backlight bulb, it converts low voltage DC power into high voltage AC. On most laptops the inverter board is located inside the display assembly below the LCD screen and you can get access to it if you remove the screen bezel (LCD mask). When the screen inverter goes bad the backlight will not turn on anymore or it turns on for a short time and then goes off, but you still can see a faint image on the screen and the external monitor works just fine. First of all I would make sure it’s not just a loose connection and reseat connectors on the inverter (it looks like you already done this part). Next, I would try replacing the inverter board. It might fix your problem with the backlight. It’s possible that you have a faulty cable, bad motherboard or even bad LCD screen, but I would try replacing the screen inverter first.