We’ve just replaced the touchscreen unit on a Sharp EPOS till.
The device was not working properly and the mouse wouldn’t point in the right place despite multiple re-calibrations.
Usually this kind of erratic touchscreen mouse behaviour in EPOS tills is due to dirt and dust that naturally accumulates at the edges of the screen.
We took the till to pieces to clean the touchscreen unit and found the cause of the problem was more permanent. Something sharp had been scraped along the bottom edge of the screen (see the photo).
We replaced the touchscreen unit taking the opportunity to clean all the dust from circuit boards, fans and heat sinks and reassembled the till.