Hello everyone im having an issue with an HMI KTP 600 Basic Color PN, the issue i Have is that when the HMI start it works fine, but after an hour or something like that the buttons and text start getting transparent and the image starts like “shaking” I Open the HMI, there is not something like broken or fused, what can i do?

maybe a backlight problem in the circuit? or maybe a screen issue? 

i dont know if its a better option to buy screen as a repair part or maybe a new pcb board,

or someone maybe can tell what do i need to look for or change.

I would buy a repaired one and send the old one to Siemens repair center. 

Most propably the LCD screen is at the end of life.