Chosen Solution
Hi. I have iPhone 6 and the brightness slider slides but it doesen’t do anything. The backlight works but it’s wery low (like its lowest level in normal use). I have tested it with different screens without any luck. It is tropped once. It seems that the Backlight filter FL2024 is slightly burnt. If filter FL2024 is burnt does the backlight work at all or are there something else broken. Long screw damage is one option but as far as I know if there are long screw damage the iPhone is compeletely dead.
Can anyone help?
Have you tried measuring the resistance of the filter? FL2024 has a DC Resistance of 0.8 Ohms so if you measure it in-circuit, it should look like a short. Ideally, you want to remove it, to properly measure it, in case there is any impedance in parallel with it. If it is measuring in the low Ohms (but not 0.8), then it may be constricting the current flow and inducing a higher than normal voltage drop. The filter fundamentally acts as a fuse in this circuit. If it is open-circuit, then the backlight won’t work at all. If it is “high” resistance, then it will make the backlight very dim. If you have one on-hand, it’s a cheap part to replace. Testing it helps us understand how the circuit works.
