How To Fix an iPad Air 3 With No Backlight

Problem description
When an iPad Air 3 comes in for a screen repair, then ends up with no backlight, then maybe the backlight circuit has damage. It usually happens due to the battery not being disconnected while attempting to plug in the screen. You will see the image on the screen but very dim and you will hear all the noises coming from it, but difficult to see the image.

Symptoms
Some symptoms include


 * Turns on, charges and makes noise, but the screen is dim (Figure 1)
 * iPad was working before the screen repair, but now doesn't work after.
 * No backlight even after putting back the original screen
 * Screen brightness doesn't work

Identifying the problem

 * Test with known good parts
 * Test with the original screen
 * If still no backlight, do a visual inspection of the board.
 * Look for blown diodes
 * (Figure 2)Air3 diode.png
 * Diode mode across the diode, with red probe on one leg, black probe on the other.
 * A known good diode will give OL in one direction & some reading in the other direction
 * If you get continuity across the diode, then it's likely bad
 * Diode Mode the display connectors, checking for any shorts or open line

Solving the problem

 * If you find blown backlight diodes, replace them.
 * Make sure you put in the correct orientation
 * Most iPad diodes are compatible. So you can grab from almost any donor board
 * If still no backlight, consider replacing all 3 backlight filters next to one of the connectors
 * Refer to Figure 3Air 3 backlight filters.png
 * Replace the filters, even if you get good readings across them.