Test Equipment: Oscillocopes

[MileHigh]

Note Brian's source is not an audio signal, it's the calibrator square wave.  So two diagonal dots on the screen with very faint lines in between is correct.  It looks like in the beginning of the clip the two input gains are too high so you don't see the two dots.  Towards the end of the clip he turns down the input gains and all is good.   The scope looks fine.

[MarkE]

TK -

Here's a video of me going through the X-Y display test that you suggested.  I am able to get the centered dot with the inputs at Ground, but I do not get the single diagonal that it sounds like I should be getting. Let me know if you need any more info than what I gave about my settings.  Hopefully it's just a human error issue, or at most a calibration issue.

In the video I had the probes on X1.  I tried it before the vid with X10 and the only difference it made was where I had to have my V/div set, and gave the exact same traces.

https://www.youtube.com/watch?v=jnsx32d2krY

It looks right to me.

[TinselKoala]

Note Brian's source is not an audio signal, it's the calibrator square wave.  So two diagonal dots on the screen with very faint lines in between is correct. (snip)

Well, maybe. My Tek 2213a gives a better balance between the bright dots and the line, though, when using the Calibrator input.  The line shows up better than in Brian's video when the dots are reasonably bright. Maybe this is a result of the camera not showing the lines well in Brian's video.  I still think the two parallel lines are weird, though. There should only be one line, with length depending on V/div settings and angle at 45 degrees if both V/div knobs and probes are set the same.

Inverting the CH2 input should make the line slope in the other direction, sloping down from L to R. With two square wave inputs of adjustable phase it is possible to have a square of 4 dots with very dim or invisible lines between them, or an "L" shaped line with two bright end dots and one dimmer corner dot, depending on the phase of the square wave signals. But two parallel diagonal lines.... I don't think that should be happening.

I've shot a little video showing the use of the x-y mode to display phase shifts, but I used a pair of sine wave signals instead of square waves. This does make a difference in the brightness of the displayed diagonal trace. I'll post the link to the video when it's done uploading.

[Brian516]

TK -

I had everything set the way you described it, except of course for the probe atten setting.  I will try again with 10X, even though I tried that before I made the vid and got the same results, just had the shift in the V/div settings to compensate.

I will also try the same thing using the FG from my PC and a pair of in phase sine waves. If I don't get the proper diagonal line, I will adjust phase until I do, and post the results.

I will also try everything with the original Tek probes. First test with the cheaps then the Tek's, then second test with cheaps then Teks.

From what everyone is saying, it seems like the results of doing so from the scope calibrator varies in some brands/models.

The video I shot is showing the correct brightness that corresponds with what I see on the scope screen. I don't have it set to compensate for lighting conditions so that you see exactly what I see.  I've been trying to adjust my lighting in here to give the best view without glare on the video, but I haven't managed to hit it right just yet.  I'm working on setting up a mini-lab with some shelves and a big desk so I can give my equipment a more permanent home, and then hopefully I will be able to set up a more permanent lighting system for better vids. Maybe if I try LED lighting, or christmas lights..... haha

Brian

[MarkE]

On my TDS2024:

A 1kHz square wave using equal length cables to the channel inputs generates two dots.  If I turn on infinite persistence then eventually two more or less diagonal lines form.

A 10MHz square wave also using equal length cables makes kind of a hysteresis "S" shape.