DS1054Z noob question

[mstck]

I received my 1054Z yesterday and I am trying to understand how to use it effectively.  The first thing I tried was  to compensate the probes.   I was a bit surprised that it took a bit of time before I could get a  "flat top" on the square wave, but put this down to unfamiliarity with the scope.  I turned the scope  off  and left the CH1 probe connected to the compensation terminal.  Some time later when I turned the scope on I  observed that the  probe needed compensating again!!.  To make a long story short, if I turn the scope on  and check the compensation, it is way off. If I wait about  6mins. it corrects itself This happens on all channels.
It's as if the scope needs this time to "warm up" and settle down.  Is this normal behavior? 

 

[janoc]

Some temperature drift is normal - any electronic instrument needs to warm up before the various amplifiers and what not stabilize. Component parameters depend on temperature, for high end instruments it is common to leave them for 30-60minutes to warm up and stabilize before measurements are made with them.

Now whether the probe compensation should be off like that, that I don't know, that does seem a bit excessive.

[mstck]

 Thank you for your response.  I did a further check by applying a 2V P-P signal to the input from a cold start and turned on the Vpp measure facility. I found that it takes the same amount of time (approx 6 mins) to reach a stable reading of 2V p-p.  Once it had settled, subsequent readings were  stable.  The unit seems to be taking this amount of time to settle.  I would be interested in finding out if any one else has observed similar behavior. Should I return this unit as broken?
Thanks.

[David Hess]

On my various oscilloscopes, the probe compensation drifts at most 1 minor division during warm up.  What you describe could happen if the high input impedance attenuator and buffer inside the oscilloscope were poorly designed or manufactured.  It would not surprise me if Rigol considers it normal but it would be nice to know if other DS1000Z oscilloscopes suffer from the same problem.

The high impedance input attenuator is switched in at 500mV/div and higher so you could test the compensation with and without it.  It should not make a difference.

It is less likely that the compensation output signal is the problem but I would also try using an external compensation source like a function generator or logic gate output just to be sure.

[Fungus]

Are the probes on 1x or 10x?

[mstck]

The probes supplied were set to 10X.
 I tried with a different set of probes  and observed the same problem. Based on the comments I have seen, it would appear that many of the members have this model, and I would really like to know if this behavior is  common or unique to this unit.

[mstck]

Are the probes on 1x or 10x?

The compensation output does not appear to be the problem.  Applying a signal from a function generator  on startup  results in a delay of about 6 mins. before  the correct  value is displayed.

[rstofer]

The user manual says to allow 30 minutes of warm-up before doing a self-calibration.  I don't think waiting 6 minutes for probe compensation to stabilize isn't unreasonable.

[Kryoclasm]

Did you make sure to have the ground lead attached to the test ground post when you were connected to the sq wave post?
Not sure if it would make much of a difference other than keeping common mode noise down.

[JohnPen]

I have not seen a problem with probe compensation on my DS1054Z (hacked).  Starting from cold the scope compensation test point, flat top, is spot on and does not alter noticeably over the first half hour or indeed much longer time periods.  I have not checked the amplitude accuracy, from switch on, from an external calibrated source but the graticule displayed amplitude does not alter and the measurements are stable.  Only tested this on Channel 1.  Ambient temperature was ~24 degrees C in work area.  I have had in the past some problems with the supplied probes which relate to the X1/X10 switch on the probe and an intermittent connection problem with one of my probes however.

John

[bd139]

Mine is flat straight after power up.

[mstck]

Thanks for taking the time to check your units and confirm that this scope appears to have a problem.  It appears to be taking some time to achieve thermal stability.

[Fungus]

Here's mine immediately after power on (the USB stick was ready and waiting) and about 15 minutes later.

There's no real difference in compensation quite a big difference in peak-to-peak voltage (0.1V difference!) and surprisingly big change in DC offset voltage (highlighted in second image).





If you save the two images and flip between them in Windows photo viewer using left/right arrow keys you can really see the difference. I didn't expect that much, it just goes to show the importance of warming it up before use and before calibration.

I took another screenshot about 10 minutes later and there was about two pixels difference between the two. I can say it's fully warmed up after 15 minutes.

Maybe a more controlled test is in order to see how long it takes, eg. taking a snapshot every 10 seconds. I'll have to let it cool down for an hour first.

[HoracioDos]

Hi.

I have the same problem with the DS1054Z but I think it's related to the probes. I have to adjust one of them almost every time I turn on the DSO. Perhaps you may find this thread useful. Did you try connect a 50 Ohm cable (RG58) from reference to Ch1or Ch2 and check the waveform?

https://www.eevblog.com/forum/beginners/very-basic-oscilloscope-questions/25/

Hope this can help

[mstck]

Hi.

I have the same problem with the DS1054Z but I think it's related to the probes. I have to adjust one of them almost every time I turn on the DSO. Perhaps you may find this thread useful. Did you try connect a 50 Ohm cable (RG58) from reference to Ch1or Ch2 and check the waveform?

https://www.eevblog.com/forum/beginners/very-basic-oscilloscope-questions/25/

Hope this can help

Thanks for the link. I have tried probes from different manufacturers and observed the same behavior. This leads me to believe that my issue is not related  to the probes.
In an earlier post I mentioned that I used a FG instead of the Compensation source to try to get to the bottom of the issue. In this test I used a 2.0 Vpp sine wave  instead of the square wave and observed that the  measured  peak to peak voltage  started at 1.74 V on a cold start  and stabilized at 2.08 V after about 6 mins.  I used a second scope to monitor the output of the FG  and observed that this remained constant at 2.08 V throughout the test.   I tried a self calibration this afternoon but the results are the same.

I checked the firmware version of my scope and it is 00.04.04.SP3 
The latest on the Rigol site is 00.04.04.03.02

Can someone tell me if these are the same?
 I am fresh out of things to try.

[Assafl]

They are the same FW versions.

I checked and mine "droops" a bit less than a minor division on the 500mV range (probably waited 20 minutes).

[JohnPen]

Hi mstck,

Can you tell us what ambient temperature your work area is as you may have a greater temperature shift on warm up? My ambient room temperature is about 23 degrees C.
I have since tested with a nominal, I don't know how accurate it really is, 2 volt pp square wave from my Feelltech FY3200S.  The connection is via a 50ohm terminated coax to my scope.  From a cold start  my scope shows a Vpp of 2.02/2.04 volts consistently from switch on to over 30 minutes.  Incidentally my scope is now just over 2 years old so well settled in.

[mstck]

HI JohnPen

Ambient room temperature is 27C.  The test setup I used is identical to yours in every respect  . I just used another scope to ensure that the output of the FG remained constant.  Thanks for taking time to run that check.  The unit does reach a stable state, but it does take some time to get there. I might just let it run for 24 hrs or so to see what might happen.

[alsetalokin4017]

The compensation drift reported by mstck is not normal.
I would have suspected the probes first (something like not having the springclips snapped firmly and fully into position which does take a bit of force) but if the problem still exists with other probes that would tend to rule that out. Also this would not tend to correct with warm-up.

The DC offset drift reported by Fungus is normal, although a bit large.

I wouldn't recommend trusting quantitative measurements until the scope is warmed up and self-calibrated for the current ambient temperature.

Burning in for a few hours is always a good idea to do before the vendor's warranty runs out.