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  • Some decades ago when I was still an engineering student, my team had to present an electronic assignment. The damn circuit didn't work, no matter what I did. So I decided to go ask the teacher for advice. I walked away a couple of meters, when my teammates told me that the circuit finally started working. As soon as I went back, it failed again. We soon determined that it failed only when I was near it. My teammates presented the assignment while I was at the other side of the lab. We passed the assignment, and sure enough, when I approached again to pick up my things, the damn circuit stopped working again.

  • I've had a couple of issues like this:

    • Wireless mouse has a flaky connection. Turns out the issue was the USB port it was plugged into (probably RF interference as other devices worked fine on that port)
    • We had a couple of radio receivers in a server rack. The scale of the project had shrunk over the years, so what used to fill up 2 racks now only half filled them (mostly because of upgraded components becoming faster and smaller over the years). Another project needed needed some rackspace, so we reracked everything into a single rack. When we were done, we found that one of our receivers couldn't get a signal, and another would lose it regularly. Checked over all of our connections and the antennas, but everything seemed normal. Turns out something in the other project was blasting out RF interference.
    • We would occasionally need to manually move data on/off a server using a USB2.0 hard drive. This worked fine for years, until one day we had a server that would randomly disconnect from the drive a few seconds into the transfer. Tried different ports, same issue. The drive itself worked with all the others, so we decided the issue must be with the server. We swapped it out for a brand new one with plans to send the old one back for warranty repairs. Except the new one has the exact same issue. Both servers came from a newish batch from the OEM. Turns out that the earlier versions had a hardware "bug" where the USB ports would source more than the 500ma allowed by the spec. Since they fixed that, our drive would trigger the current limit during sustained use and temporarily depower the port. Solution: get a USB Y cable and power provider power from a wall block
    • I had a mouse that would double click (or more) when you pushed the button. This was pretty obviously a hardware issue, but I figured I could just tell the computer to ignore double clicks that happened "too fast" and avoid needing a new mouse. In theory that should have worked, but the input stack on Linux turned out to be a giant web that I couldn't figure out, so I ended up opening the mouse and soldering on a random capacitor I had lieing around.
    • We had a laptop with a dead monitor that would mysteriously work at times. It turns out that most of the time, it was sitting on another laptop (of the same type). Those laptops had a magnet latch to hold them shut. It turns out that said magnet also was used as part of a "laptop closed" sensor that would disable the monitor, and the bottom laptop would trigger the sensor in the top one.
  • I worked for a cable company as the sysadmin. They were having trouble with channels going off randomly but most often in the morning and evening. One day in the middle of the day I'm out there with all hands on deck discussing the problem when one of the employee's showed up in his older GM truck. Just as he arrived the channels went out and they jumped on the scopes and cable meters to start looking for the problem. He got out it stopped. We all stood around for a few minutes saying it was going to be a long day if we couldn't figure this out. After a little bit he was instructed to go back to burying drops on his schedule. The second he cranked up the problem started. He drove off and it stopped. Three of us just looked at one another and we called him back. Sure enough as soon as he drove up the problem started. He was given instruction to not drive past the office gate and the problem went away. As to what on that old truck was throwing out all the gigahertz interference we may never know. That truck was gone withing a week.

    • I can't say if the frequency is right, but poorly shielded spark plug wires will send all kinds of EM out. You know, the older cars where if you touched one of those wires you'd feel it, or you could see the aura if it was dark jumping around.

  • I had a similar case. Was going crazy about the horizontal lines on my screen. They weren't always there, just when a certain color took up most the screen or when a window was placed in a certain position. Suddenly bam, my whole screen looked like grip tape.

    I started troubleshooting the display, compositor, checking the software for some sort of night mode or eye protection. Nuthin.

    Then my friend says, "Are you using display port or HDMI? Try switching." I switched to HDMI and god fucking dammit if it didn't just work. Afaik it was something to do with the nvidia proptietary gpu drivers, because when I'd roll them back it didn't happen.

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