We have designed an HMI, which will contain a 10.1" TFT with PCAP touch panel.
I am using an enclosed power supply to convert the 230V AC to 12V DC. Only DC positive and negative is connected to my board.
I have noticed that when I use to draw over the LCD, the processor will not detect some of the coordinates. I couldn't reproduce the same issue in another building of my company, which lead me to suspect the earthing of the building.
I found the issue in my workplace. Finally, I found that the earthing in my workplace is not proper. When I found out the earthing issue in my workplace, I gave a separate earth connection to my power supply chassis, snd the touchpanel worked fine without any issue.
From the above point, I assumed that the issue is occurring with the noise on power rail - mainly common-mode noise.
In this scenario, I solved the issue by giving proper earthing. But I can't expect all others to provide proper earthing. (Most of the building earthing will be proper, but there is also a chance it may not OK.)
Can anyone suggest a way to suppress this noise in my board without earth connection?
I already tried with different common-mode chokes, but it didn't come out well.