Failed 4R7 Coil will cause iPad 2 Screen to go Dim
IPAD 2 4R7 Coil Location
It may take a professional to tackle this repair job.
Unlike laptops and other electronic devices that have an LCD screen the iPad and iPad 2 utilize a coil to regulate and provide voltage to their screens. The part number for this coil is 4R7, and it is called a backlight coil. They can be ordered off of Ebay. In most cases a failed 4R7 Backlight Coil can be identified by the discoloration that occurs from a burnout. However, this is not true 100% of the time, in certain cases when you are unsure you may have to take it to a professional repair shop where they can test your screen with a known good working one.
This coil can fail if you fail to disconnect the battery and discharge any excess power that may linger in the system during a screen replacement or at any time during other repairs that require going inside the guts of an iPad. Also if you have an iPhone that has a screen that appears to have failed it uses a similar backlight coil, and its part number is 6R8.