The Tale of the Flickering Monitors, part 2: You're (not) Grounded!

This is a followup to my previous post: The Tale of the Flickering Monitors. To recap, my monitors were blinking in strange and disruptive ways. The culprit turned out to be my treadmill, and spraying some water on it made the flickering stop. If that sounds like a head scratcher, welcome to my world.

After last week’s wild and crazy monitor adventures, I thought I would be done writing about computer screens and instead focus on what I generally try to use those screens for: work. But there were still some loose ends to tie up. Spraying the treadmill cut down the flickering, but it was only a temporary fix. Once the water dried, the flicker returned and I had to spray again. Not terrible, but not ideal.

Also, I wasn’t wearing shoes and all of this spraying was making my socks wet, which is never a good thing.

At this point I knew the problem had to do with static electricity buildup. I figured the socks weren’t helping with that, so I tried putting my sneakers on. The flickering seemed to stop. That was good, but could I do better?

I searched around a bit more and discovered a whole community of people with similar treadmill-caused monitor flickering issues. Among them, this guy (flickering at 5:30):

I wasn’t going to start playing around with wires the way he did (again, I’m a software guy). And the static discharge bands didn’t look like they would be any better than my current sneaker solution. But Mr. ElectroBOOM’s talk about electrical grounding — basically, giving stray electricity a safe place to go — got me thinking.

There was something about my treadmill’s power cord that I had noticed a long time ago and then promptly ignored: the plug was not a standard Israeli plug (I live in Israel). To compare, below is a picture of standard 2- and 3- pronged Israeli plugs, next to the thing I found attached to my treadmill:

It was unusual, but I plugged it in and, hey, it worked. I hardly gave it a second thought. Until now.

I knew that the third prong on a 3-prong plug is usually meant for grounding, but this plug didn’t have a third prong. It just had a metal strip going down the middle. Maybe that was the problem. I fed a picture of it to chatgpt. This time, it gave me some darned good information:

Ah — this is actually a Schuko plug (Type F, common in Europe).

It’s not just a “2-prong” plug. The two round pins are live and neutral, and the metal strips on the top and bottom edges (you can see them on your photo) are the ground contacts. When you plug it into a proper Schuko socket, those strips touch the grounded clips in the socket and provide a full earth ground.

So your treadmill does support grounding — it’s just that the ground is on the side rails, not a third pin sticking out.

Again, for comparison, below is a standard Israeli outlet (left) and a Shuko outlet (right):

The Shuko plug fit in the Israeli outlet. It was able to power the treadmill, just the grounding mechanism didn't have anything to attach to. I thought I might be on to something. I went back to Google and discovered the nifty product pictured below: a Shuko to Israeli plug adapter. I ordered one.

Shuko to Israeli plug adapters (https://shop.super-pharm.co.il/electricity-and-electronics/cables-and-adapters/electric-cables/מתאם-חשמל-מתקע-גרמני-(Schuko)-לשקע-ישראלי-כולל-הארקה-3-פינים-עד-16A-קבוע/p/mp-00106831)

The adapter arrived a few days later. As a test, I turned on the treadmill one more time without the adapter. It was still flickering. So I attached the adapter, held my breath, and… it kept flickering. Oh well. At least I had the sneaker solution. It beat the spray bottle, and I got to learn a bit more about plugs and outlets along the way.

---

P.S. While doing all of this, I decided to give my homemade docking station stand (mentioned in my last post) a slight upgrade so it looks a bit less like what it is: a piece of garbage. We’ll call this version 2.1: