I've been working with LM19 since about a week after it came out. I've solved all my problems, except one, and like the distro a lot. Here's the one:

My monitor times out after a couple minutes.

I've set the Screensaver to Never, I've set the PowerSaver to Never (AC or on battery). I don't know what else to set.

I currently have 4 distros in different partitions on my laptop. I have zero problems with KDE Neon or Ubuntu 18.04 MATE, and am just getting started on PrathamOS so no comments there. I've gone through lots of distros, liked many, disliked some, and couldn't get some to work at all. I'm NOT a Power User (in Linux), just a perennial n00b who likes trying things.

If I could get this problem solved, LM19 would be my daily driver.

I should also point out that I'm running on an external TV as a monitor (32" is much easier on my old eyes, and I stream all my TV). I have checked the TV settings, and, again, it works fine on the other distros currently (and recently) installed.

Try the following command:

OK, I tried it. Is something supposed to happen? Do I need to run it every boot?

zaivala@zaivala-ThinkPad-T430:~$ xset s off -dpms
zaivala@zaivala-ThinkPad-T430:~$

Try a long time, such as 120 minutes, long enough for most movies. Each time you move the mouse or strike a key, timeout should reset to 120.

Another possibility, put the following in /etc/X11/xorg.conf.d/50-monitor.conf (if it doesn't already exist; otherwise add the option line to it):

Does it solve the problem?

No, I don't think you shouldn't have to run it every boot. Don't quote me on that. Let's see if it works first though.

OK, I didn't get a chance to see if it worked. It was not, however, "sticky", that is, it has not continued to work through successive boots. I think I have time to see if it works this boot. Will go do that.

PowerSaver has already been set. Everything has been set which can be set, unless there is a hidden setting somewhere.

xset s off -dpms - this works, single instance. When I reboot I have to enter it again.

Why don't you add that command to your startup programs?

LOL because I don't really know how. I will go try to fumble my way through that.

I also found that Caffeine DOES NOT WORK in LM19. I tried to use that instead of the xset command. This is not an Ubuntu 18.04 issue, as it works fine in Ubuntu Budgie 18.04 and Ubuntu Studio 18.04.

Which desktop environment variant of Linux Mint 19 are you running?

MATE

Thanks. You can make an application or a command execute at startup through MATE's Control Centre (Personal->Startup Applications: Add).

I appear to have made a successful attempt at doing that back when I posted I wasn't sure I could. Thanks. I thought your question had to do with which desktop Caffeine would not operate in, and yes, it could be the same answer. I find Caffeine to work very well in Budgie.