HP150 Touchscreen diagnostic

I can think of at least 3 problems with that approach : 1) It only checks the emitters, not the detectors (or the path through the 4051 muxes) 2) You may be able to see if a beam looks a bit dim (e.g. the IR LED is weak, or more likely it's covered in dirt), but will you know how dim is too dim to work? 3) I am not sure my video camera has much sensitivity in the IR. It depends on which vidicon is fitted, I think. Yes, and the HP150-II suplement. I don't find it that good. The schematics are incomplete, there's at least one error (in that what is shown couldn't work correctly), and I think there are some other differences with the mahcines I have. The programming information is not that clear either (e.g. the section o nthe commands ot the 8042 doesn't explain what the touchscreen diagnostic command does if there are more than 2 blocked beams) -tony