Chosen Solution
Hi guys I have an iPhone 6s in repair from a fall in the water, I made ultrasonic cleaning and has broken down but the backlight sometimes disappears and if you spot a flashlight you see, the touch is working without backlighting. I tried another screen the same thing, I noticed that it warms up near the processor! Can the filters be?
Update (10/17/2018)
There are probably shorted filters, capacitors used to power the left / right hand side of the screen’s backlight circuits. It would be obvious which components are the culprit if you take note of any corroded components on the board before ultrasonic cleaning. You may be still able to notice under microscope but it’s going to be harder as the evidence is mostly gone after ultrasonic cleaning, which is personally why I prefer to replace / remove corrosion from suspect components before ultrasonic cleaning). If I’m correct these are under the metal shield that covers the processor and backlight driver circuit. You can inspect most of the components behind the logic board as you can peel the sticker on both the metal shields. You’ll need to measure some capacitors, filters, coil for backlight circuit with a digital multimeter and see if they are shorted to ground (both sides of components show no resistance to ground) I’m not exactly sure what components should be measured but I’ll page @refectio for advice on how to proceed with diagnosing no backlight.
