answered
2017-03-22 16:53:36 +0200
As far as i understand, touch ic selftest in csm utility (run it from terminal) recalibrates touch screen, but it is not likely that doing this will help you, at least for long.
I had a similar issue, but mine wasn't cracked: some parts of the screen wasn't responding to touches and, sometimes, whole screen won't work (i too think that there was a constant click). As I work in cellphone repair store i tried to understand this situation somewhat better, and just today I tried to dissassembly the touch screen+display assembly and this is what I found out.
Touch screen on jolla phone is an assembly of some thick film layers with contacts that connect this layers (layers are located on top of each other, like on membrane keyboards, and glued together with optical glue applied to the whole surface of each of this layers ). This part is glued to a piece of glass on one side and to display on the other side, again, using optical glue to whole surface, then this whole assembly is glued to the case using special duct tape applied to the edges of the assembly. What causes the problem is that too much glue is applied beetween touch layers from factory. With time, excess glue starts to apply pressure to the edges of touch layers. Initially, this creates vertical yellow lines on left and right sides of display (this is the result of applying pressure to the ips matrix, which jolla phone uses), and then the touch layers start to slowly detach from each other from left and right sides of the screen, where all contact conductors are. When this conductors detach from each other, parts of touch screen that were regulated by affected conductors cease to work. Also, as a result of too much pressure applyed to touch layers, some points on touch screen becomes easily shortened, which makes touch screen controller register constant clicks.
As of now, I don't know if it is possible to repair touch screen in this state, but I'll try. I'll leave a reply with results sometime later.
