So I got a QA100 digital oscilloscope/LA combo. It appears to work... I just don't think I know how to use it. The instructions appeared OK, but maybe its less to do with *this* scope and just more about scopes in general... but I'm getting nowhere fast.
It has a test point that's always outputing a 1 khz 1v sine wave. When I connect the probe to that, I indeed see the wave as expected. That's how the instructions say to confirm its all working fine. But then I can't see ANYTHING else. As a simple (I thought) example, I plugged in a USB connector with accessible +5v and GND leads. I expected that if I touched the probe to the +5v that I'd see a line on the screen representing that. But I get nothing. The software has a DVM setting so I tried that, and it doesn't react at all when I touch +5v. I touch the 1v reference again and it responds. I test my +5v with a regular DVM and it shows 4.91v. I tried the 2nd probe... still no luck.
What am I doing wrong?
I don't know that it matters, but I had a little trouble with calibration. It asks me to use an external DVM to read the true RMS voltage on that reference pin and I got something like 1.2 but it wouldn't let me enter that because it only accepts a value between 0.85 and 1.15. It also says you can leave it at 1.000 and it should still be fairly accurate so that's what I did. Now when I use the built-in DVM function on that reference it shows 1.59v RMS so I'm a little confused on that as well.
I have contacted their customer service but I thought I might get quicker help here as they are pretty slow to respond on their forum.
Thanks.
- Steven
It has a test point that's always outputing a 1 khz 1v sine wave. When I connect the probe to that, I indeed see the wave as expected. That's how the instructions say to confirm its all working fine. But then I can't see ANYTHING else. As a simple (I thought) example, I plugged in a USB connector with accessible +5v and GND leads. I expected that if I touched the probe to the +5v that I'd see a line on the screen representing that. But I get nothing. The software has a DVM setting so I tried that, and it doesn't react at all when I touch +5v. I touch the 1v reference again and it responds. I test my +5v with a regular DVM and it shows 4.91v. I tried the 2nd probe... still no luck.
What am I doing wrong?
I don't know that it matters, but I had a little trouble with calibration. It asks me to use an external DVM to read the true RMS voltage on that reference pin and I got something like 1.2 but it wouldn't let me enter that because it only accepts a value between 0.85 and 1.15. It also says you can leave it at 1.000 and it should still be fairly accurate so that's what I did. Now when I use the built-in DVM function on that reference it shows 1.59v RMS so I'm a little confused on that as well.
I have contacted their customer service but I thought I might get quicker help here as they are pretty slow to respond on their forum.
Thanks.
- Steven
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