Simple question about scope (DS1102E) and AC ripple

Feel kind of stupid asking this, but you knows know this stuff well…

I'm trying to use my DS1102E to look at the output of a bridge rectifier. Goal is to see the voltage and whether any AC ripple exists.

So I connect everything up, make sure the probe ground is connected to a proper ground, and press the auto button.

I see the voltage is going between about 25V and 26V. This is obviously DC.

If there was AC ripple, I assume I would see some large swings down to zero and back up, yes? Or do I have that work.

I'm also running into another problem. I wanted to "zoom in" on the area between 25V and 26V, just to see what's going on there. The "auto" mode picked 5V as the vertical size, so 0V is toward the bottom of the display and 25V is toward the top. However, if I use the vertical scale knob and change it from 5V to 2V (the next step down), I hear a little click and see nothing. Even if I use the position knob to ensure I should see something, it's not there. I'm certainly doing something wrong here.

Bottom line: I'd appreciate any thoughts about measuring/viewing AC ripple with a scope as well as any thoughts about why I cannot change the vertical scale to < 5V in order to look more closely at the bouncing between 25V and 26V.

Thanks so much!

… Altan
www.aaarpinball.com
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Received on Mon Aug 26 17:44:47 2013