maybe someone can help me with this scope / function generator issue. Attached is a pic of how my new scope is
displaying a square wave generated by my Func. Gen. The sine wave and triangle waves are just fine, but the square wave is as it is in
this picture. Function Gen. is set for 1khz and 1 volt. The scope is a Rigol 1054z. As you can see the display is not of a nice neat
square wave even though the func. gen is set for square wave. Any help is much appreciated.

mark

 

Probe compensation in the X10 mode. If they are the probes that came with the scope, there is a small hole with a screwdriver adjustment. Also, there should have been a small plastic screwdriver for those. Try turning the adjustment to flatten the square wave. If you go too far, the square shoulders will become rounded. Congrats on the new scope. I have the same model.

 

Hello,

Are you using AC input on the scope?
This might cause the strange pulses.
On DC it should be neat.
If the scope is already in DC, check the probe on the internal reference of the scope.

Bertus

 

Probe compensation in the X10 mode. If they are the probes that came with the scope, there is a small hole with a screwdriver adjustment. Also, there should have been a small plastic screwdriver for those. Try turning the adjustment to flatten the square wave. If you go too far, the square shoulders will become rounded. Congrats on the new scope. I have the same model.

okay so I adjusted the probe. Also put it into 10x mode. The tops of the square waves aren't flat flat, but much better than before. I'm still figuring out this scope. It is nothing like the old clunker crt. Have you tried doing a simple r-c time constant with this scope using a 1khz and 1volt square wave? What circuit did you use? resistor and cap values? Thanks. I'm heading back to school to study EE, so I better get caught up.

 

The tops of the square waves aren't flat flat, but much better than before. I'm still figuring out this scope.

Post a picture, lower resolution than the first please.

The first picture, clipped and rotated:

 

Since you state that you switched to the 10X mode on the probe, I can only guess that the original post was while in the 1X mode. In that case, I would suggest using the 1KHZ test point at the lower right of the scope as a test. You may have a problem with your function generator.

 

Since you state that you switched to the 10X mode on the probe, I can only guess that the original post was while in the 1X mode. In that case, I would suggest using the 1KHZ test point at the lower right of the scope as a test. You may have a problem with your function generator.

Okay, so with the probe on 1x, and connected to the calibration points on the lower right of the scope, I can adjust the probe to produce a perfectly flat square wave. The function generator has no problem producing a sine wave or triangular wave. Only the Square wave requires 10x on the probe and an adjustment. If I leave the probe as it is adjusted in 10x and connected to the func. Generator, and then connect it to the test point on the scope..then set it for 1x, the square wave is distorted. Something is fishy.

 

That tells me that your function generator is not putting out a square square wave.

 

Hello,

Is the output of the fuction generator AC or DC coupled?
In AC there can be a distortion on the squarewave.

Bertus

 

That tells me that your function generator is not putting out a square square wave.

I was thinking that may be the case. I guess the only way to know for sure is to borrow a function generator from someone and try it out to see if it has the same problem...if not then the Func. Gen. that I've got is not making a square wave. arggh. Thanks.

 

One other thing that confused me enough to turn my scope on and test it. The compensation adjust on the probe should only have and effect while in the 10X mode, and no effect in the 1X mode. If you set it so you have good looking square waves in the 10X mode, that means that the probe has been matched to the input of the scope and you should see a good representation of any external signal you look at.

 

I guess the only way to know for sure is to borrow a function generator from someone and try it out to see if it has the same problem...if not then the Func. Gen. that I've got is not making a square wave.

Do you have cables to connect the function generator output directly to the scope?

 

Do you have cables to connect the function generator output directly to the scope?

... and do you have a good ground connection from your probe ground to the function generator ground?

 

One other thing that confused me enough to turn my scope on and test it. The compensation adjust on the probe should only have and effect while in the 10X mode, and no effect in the 1X mode. If you set it so you have good looking square waves in the 10X mode, that means that the probe has been matched to the input of the scope and you should see a good representation of any external signal you look at.

Ok, got it working. The function generator is fine. Thanks. The only thing I didn't quite figure out is why the Function Generator says 1.01v and the scope says 1.5 approx. volts...I guess it is due to the 50ohms at the function generator? Make sense?

 

Hello,

What do you see on the scope when you connect the function generator to the scope with a BNC cable?
(I assume both have BNC connectors on them).
With the BNC cable, you can also switch the scope to 50 Ohms.

Bertus

 

the Function Generator says 1.01v and the scope says 1.5 approx. volts...

My guess is that the Function generator is outputting 1Vrms and the scope is reading a little less than 1.5V peak-to-peak.

1Vrms approximately equals 2.83 Volts peak-to-peak for a sine wave, so I am guessing that not only are you failing to compare like-for-like, but maybe you have 50 Ohms setting wrong on your function generator.

.... or maybe you are reading Vmax on your scope? still guessing wildly here.

Getting 50 Ohm setting wrong on function generator causes values to show double or half expected value.

.... but this is all guesswork, as I am not in front of your test equipment

NOTE: - edited in view of BillB3857 observation regarding no scope selection for 50 Ohms

 

The scope the OP is using has a 1Megohm direct input. Using a 10X probe raises the input to 10Megohm. There is no switch to select 50 ohm input.