Samsung WM75A User Manual page 65

Touch function issues
The icons can be touched but the drawings cannot.
Touching does not work when HDMI connection is used.
I use two pens, but they do not work well.
There is a screen touch malfunction such as slow or
inaccurate responding.
Use the provided product-specific pen.
Check whether the TOUCH port on the product is connected to a USB port on the PC using
the supplied USB cable.
" HDMI 1 or DP → TOUCH on the rear of the product
" HDMI 2 → TOUCH on the tray
Make sure that there is enough space between the two pens at multi-touching.
Make sure that there are no foreign substances on the screen surface.
Check whether the screen is broken.
Make sure that the product is not exposed to direct sunlight.
When the product is turned on after turning off, do not tap the screen because touch
calibration is performed for 5 seconds.
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