External monitor issues: intermittently turning off

I recently started connecting my Librem 13v4 running purism amber (fully updated) to an older external monitor (24" Acer, 1920x1080 resolution). Unfortunately, the monitor seems to turn off and back on quite frequently. The monitor, HDMI to VGA, and VGA cable are regularly used to connect raspberry pis as well, that always works w/o any issues. I have read on the forum and other topics and found many posts related to higher resolutions. The only thing that comes close to my experience is this post:
See the post by richard.kolla from Aug 20, 2019.

When I’m writing, the screen usually does not turn off. However, whenever I start a program, I’m sure it will go off and come back on. The same is true when I compile my LaTeX document that I’m writing on - all fine while writing, a sure turn off - turn on cycle when compiling.

Even weirder: I have been running some file synchronizations for backup purposes using freefilesync. Everytime the monitor goes off and on, the write speed drops to 0. This does not happen when I unplug the external monitor, everything syncs nice and fast.

Finally: I logged out of my account and tried Gnome Classic and Gnome Xorg, same in every environment.

Any ideas on where this issue might have its root?

So this is some kind of active adapter?

Anyway, I would at least look in system logs to see whether there are any messages that correlate with when you have the problem.

How long is the monitor off for, typically?

Do you have the laptop lid open or closed? If open, is the internal display also turning off?

Really I have no idea. :slight_smile:

Not sure if it’s an active adapter. It was for sure cheap :wink: Here is a link to the model. I do notice now that it has a USB port… is that for power? Sorry for my ignorance here, when it comes to graphics adapter I usually get frustrated with all the standards…

I don’t see anything in dmesg, any other places you would look?

Monitor is off for around a second or so. If the machine is doing some thinking, it can be longer. For example if I render a figure in python let’s say, it can easily be a few seconds.

Laptop lid is open and the display is extended to have the monitors join. Internal display does not turn off…

Edit: I tested if the problem solves itself if I connect the adapter to power: same behavior, no improvement unfortunately.

Apparently so. From their web site:

The device also includes a 5V micro USB port to provide additional power.

So I take it that you have a power supply (AC/DC adapter) that meets those requirements. A normal Pi power supply should be that, I think, although I don’t know what current your video adapter may require. Does your video adapter come with a suitable power supply? What power supply are you using? Did the video adapter come with any documentation that explains when or whether power is required? and if so how much?

I would assume that the other socket, next to the micro USB input, is a standard 3.5mm analog audio output (headphones or speakers). Are you using that? Could you test that to see whether the audio drops out when the video drops out? Note that to test it you would have to configure to output sound via HDMI. You would also of course have to be doing something that is outputting sound continuously.


Hmmm. I was hoping for more than that so that it would be easy to check the state of the computer while the monitor is off.

Can you borrow a vanilla HDMI monitor from a friend? i.e. for fault isolation purposes.

Adding: Are you using the screws to secure the VGA cable to the video adapter?

Nope, also didn’t come with any documentation.

5V, 3A, does not make a difference if it’s plugged in or not.

Audio does not drop when the video drops.

I checked in /var/log/syslog, actually just tail -F ed it to observe what happens when the monitor kicks out: nothing…

Now another interesting fact: I just moved back to the monitor to check your hints out and put this together. At first I couldn’t reproduce the error. However, I did not have the charger plugged into the laptop. Plugging the charger in, I can make the video fail. The same ways to make the video fail do not work when the charger is unplugged… That would kind of indicate some hardware issue.

I will test it with an HDMI monitor tomorrow at work and will update again. Thanks!

1 Like

Dirty mains? Don’t suppose you have either a power meter or a UPS or both to investigate that?

Could absolutely be! I’ll bring my adapter to work tomorrow and test it there with a VGA display. The main there should at least be different (and not dirty, otherwise we have other issues…). There I also have a HDMI display, so that will be another test. More soon and thanks @kieran

1 Like

So, some news:

I tested connecting the computer in the office to the screen there, I had an HDMI to DVI adapter laying around. All no problem, no flickering, nothing. Resolution 1900x1200 was immediately recognized, all worked great.

Since I forgot my HDMI to VGA adapter at home (go figure), I just took the HDMI to DVI cable home with me to test in on my screen at home. Plugged it in, no flickering, whatsoever. So either a bad adapter or a bad VGA input? Still puzzled why I never had issues with the RPi, but oh well, I’ll take that as a solution for now :slight_smile:

1 Like

HDMI to DVI is a passive adapter i.e. can be done as just a cable. A lot less room for problems to creep in. Probably cheaper too.

Active adapters are notorious for being partial solutions i.e. incomplete, hacky implementations that work most of the time or emulate correctly most of the time but … not all of the time. Given the choice between bad adapter and bad VGA input, I would lean towards the former, admittedly without much evidence in this case (given that the Pi works).

Indeed, like $8… no idea why I didn’t do that in the first place, but then again… Thanks for your help @kieran, very much appreciated. And maybe this helps somebody in the future too!

Got the same cable now again, some more intense usage and it’s still happening whenever plugged in. I guess it might be dirty power lines? Still a bit puzzled why I would see it on the HDMI output and nowhere else…

You are not the only one to have problems of this type e.g. https://forums.tomshardware.com/threads/monitor-randomly-goes-black-for-a-second-every-so-often.1296930 Don’t expect that discussion to solve your problem though. Too many conflicting answers.

Thansk @kieran, this is interesting.
A small update. I found another monitor with an HDMI in which I used all of this week. No problem at all. I’m still puzzled why the HDMI to DVI makes such an issue when the charger is plugged in but not otherwise, and all is fine when the HDMI is plugged in. Just figured I’ll put it out there :slight_smile:

1 Like