Oscilloscope square wave

[Jononomous]

Hey All,

Got a used oscilloscope.. model BK Precision 100Mhz 2190A

I'm using the built-in square wave generator to calibrate the leads... and strangely it doesn't seem to be working correctly.

Here is a pic:

**broken link removed**

Shouldn't the square wave be larger? Also, the notch for the square wave gen says .5p-p... so I set the volt/div to .5 and its just a straight line... i had to crank the volts/div over to 5mV to get it to detect even this little wave... is something messed up? I messed with the timer knob... to get this wave or a slightly longer one I would use .5ms or .2ms respectively.

Did I buy a lemon or is there something I am doing wrong?

 

[KeepItSimpleStupid]

What do the probes say? x10, x100? Do the probes have a switch for x1, gnd or x10?

The calibrator is more likely to be used to calibrate the probe compensation.

 

[Jononomous]

The probes have X1, X10, and REF

I have tried using the trimmer on the probe but it wont straighten out that square wave... the picture above is shitty quality but the lines loop upward and are spaced apart, the pic makes it look like a sine wave.

 

[KeepItSimpleStupid]

The trimmer will only work in x10 mode which means the volts/div on the dial have to be multipled by 10.

One of the tough things if you never used a scope before is getting a waveform.

Use the GND position to get a stable flat line on the scope in the middle of the CRT.

Use auto-trigger and DC coupling to start for the square wave. Make sure your triggering on probably composite or the channel in question.

Make sure you are using the main time base and not using the delayed time base.

Remember that you may only see the tops of the waveform because of the fast rise time.

This isn't step by step. It's to give some info to get started. I don't know what controls your scope has.

 

[MikeMl]

The built-in calibrator likely makes a square wave at 1kHz, so the time base should be set to 0.5ms per div or so. Offhand, I'd say your vertical amp is messed up. In case you have a bad probe, just connect a clip lead from the calibrator direct to the vertical input using a short piece of wire to make contact with the center of the BNC.

 

[Jononomous]

Thanks KeepIt and Mike, tried keepit's settings and switched over to mikes settings... still only a flat wave... so Mike I would imagine there is indeed something screwed up in this thing... thanks guys!! Ima try to get BK to fix it for cheaper than a new one... but there of course is a point where it becomes more beneficial to have a new one lol.

Thanks again guys