I have had my lilliput 7" since about June. The touchscreen was initially rather a pain to get working but I found this was due more to a bad connector from the screen to the computer. Well, it worked perfectly for a couple months... my car went in for repairs and they detailed the interior and shortly after that I started getting the touchscreen working very intermittently before it finally just stopped working completely in Sept. although there were no errors in Windows and it said the controller was there and working. Touching the screen yielded no results though. Well, I finally got around to trying to troubleshoot the problem.
I took the screen apart and it looked like the double sided tape around the housing for the touchscreen had gotten indented not allowing a cushion. I checked resistance using the plug and pushing on the screen and was getting resistance readings upon touching as expected. I then traced every connection back to the controller board to make sure I had continuity and then made sure on the wires out of the controller board to the computer. I put it all back together and suddenly I have a touchscreen again... then on reboot... gone. Reinstalled drivers and it's there for a bit then when screen is touched it goes to bottom right corner. I knew I'd read of that issue so took it all apart again and added double stick tape tape around the edges... back together and voila... touchscreen again. Worked all last night.. several reboots... Went out this morning and touching the screen sends cursor to far right again... but not stuck on corner just far right. I can move it up and down the far right side but it will not move left. I tried calibrating again and then the screen was no longer responding...
The weather here yesterday was in the 40's whereas it was close to 55 or so this morning... How much does the weather play in the function of the touchscreen? My climate here (near St. Louis, MO) runs roughly 15 degrees to 95 degrees. The monitor is mounted on the dash. It was in the 90's when the screen initially started acting up.
I am trying to figure out what I need to replace, if anything, as I'm getting ready to mount this in dash using a kit from digitalww. At that point it's not gonna be so easy to fix the problem and I need a permanent (or near permanent) fix. Is it the controller board? Touchscreen itself? Any ideas at all?
From your description of all the temp changes, I'd say the case is warped and pushing down on the edge. If you have a safe place to run it out of the case for a few hours, try that. At least you'd know if it's the case or TS.
Although that is a possibility, I am more concerned about resistance changes due to temperature. I know this monitor is supposed to be able to handle most of the automotive spec temperature range, I wonder if that is true. I am a mechanical engineer not an electrical and work in the automtive design filed and we have had some issues with resistances on our products being different at cold and hot and wreaking havoc on the controller.
I can probably rig something up to try it as you'd said... but I wonder if it's deeper than that.
I guess anything is possible with the lilliput. It may be going bad. Some poeple get the curve problem on the right side, others just go out after a few months, and a few had some pressure from a rough spot pressing on it or something. I've had direct sunlight on mine for hours and removed it from the bezel probably 100 times, and it stays perfectly calibrated, so I really have no experience here.