Hi there!
I was really happy to get my very first scope and I was measuring things on my laptop, but I'm an idiot and I might have got something wrong. My laptop is NOT grounded as it's connected to the power supply via a charger which doesn't have ground, just phase and neutral. I set the scope to DC Voltage and I connected the probe to the USB 3.0, expecting to see 5V but I saw 12V instead, so I got really scared and I immediately removed the probe. Then I tried it on the USB C on the side of the laptop and it was showing 12V, same goes for the HDMI and the Display Port, so I was like: Crap, something is wrong.
What I think happened is that the laptop was floating and when I connected the probe to the USB it found a direct path to ground so it was shorting the power supply of my laptop to ground. I removed the probe, rebooted the laptop and everything was working fine. I've been using the USB port for a few hours and it's working just fine, so... what happened? Why was I seeing 12V? Was I harming the ports and I was just lucky that they probably have overcurrent/overvoltage protection built-in?
Thank you in advance,
Frank
I was really happy to get my very first scope and I was measuring things on my laptop, but I'm an idiot and I might have got something wrong. My laptop is NOT grounded as it's connected to the power supply via a charger which doesn't have ground, just phase and neutral. I set the scope to DC Voltage and I connected the probe to the USB 3.0, expecting to see 5V but I saw 12V instead, so I got really scared and I immediately removed the probe. Then I tried it on the USB C on the side of the laptop and it was showing 12V, same goes for the HDMI and the Display Port, so I was like: Crap, something is wrong.
What I think happened is that the laptop was floating and when I connected the probe to the USB it found a direct path to ground so it was shorting the power supply of my laptop to ground. I removed the probe, rebooted the laptop and everything was working fine. I've been using the USB port for a few hours and it's working just fine, so... what happened? Why was I seeing 12V? Was I harming the ports and I was just lucky that they probably have overcurrent/overvoltage protection built-in?
Thank you in advance,
Frank