The Vision laptop runs the vision software -- it displays some live views of the automated trains as well as pre-recorded videos. The laptop’s internal screen is no longer actually usable: it looks fine at first, then quickly displays purple strobing/flickering lines. It does that even in the BIOS. I've made many attempts such as switching from CPU graphics to the discrete GPU, trying lower or higher resolutions or refresh frequencies… For a while I had a workaround that involved a specific sequence of DPMS on/off, and that was enough to reset the controller or something. Now, nothing makes it stable anymore. I dismantled the laptop and found no physical issue with it. Trying to replace the screen or its cable would be almost as expensive or more than getting a new laptop or a new screen so…

So instead I did this:

I moved the laptop on the side and the main display is a new 22 inch monitor. It's a good size for the space available, without being too distracting. Behind the screen is a small hill, thus we’re not blocking any view of the layout.

Ironically that more or less matches the initial design for this project -- I had anticipated having a computer hidden under the layout driving an external monitor behind the glass.

Although my initial design was to hide the machine under the layout, I quickly opted not to do that since that happens to be extremely cumbersome for maintenance, and at the same time I had a laptop with a screen, so why not use it? Similarly, here I decided to just place the laptop on the other side of the “hill” behind the glass, with a linux command to make sure the screen stays turned off.

The only follow-up I need now is to modify the vision software to turn the external screen on/off when the layout is powered. I just need to hook a script in the existing DisplayController to control Linux’s DPMS.