Agilent 3000X probe compensation problem - Page 1
Forum section: electronics / general

author: DaveDE
author_rank: Newbie
timestamp: December 08, 2011, 10:31:16 pm
content: I just received my Agient MSOX3024 oscillosope. Wow! This thing really rocks. I've been giving it a good workout, trying all of the features I can think of. However, during this process, I decided to calibrate my probes. Unfortunately I get no response when tweaking the adjustment pots in the probes. After trying two probes on channel 1, I decided to try channel 2. When I did this, the oscilloscope apparently lost its marbles and started doing all kinds of weird things. It could not display a waveform properly after that, and all channels were useless, displaying giberish. I finally got the scope back to normal after having to reload the latest firmware.Has anyone else here with a 3000X tried compensating thier probes? My probes are the N2863B models. I think Agilent has a major bug here.

author: firewalker
author_rank: Super Contributor
timestamp: December 08, 2011, 11:12:04 pm
content: Did you switch your probe to 10x in order to compensate it? Nothing to do with the later problem though.Alexander.

author: DaveDE
author_rank: Newbie
timestamp: December 08, 2011, 11:27:30 pm
content: That's done automatically on the 3000X series. I plugged a Tek probe in next and was able to compensate it although it apparently was not recognized as an Agilient probe and did not take me to the next screen for fine resolution on the compensation. In any case, it looks like the probes I have are dead for calibration. I even tried cal'ing them on a Tek scope I have, and no response. Tek probes cal just fine.Anyone out ther who actully owns one of these scopes (and probes) who can verify?

author: Unknown
author_rank: Unknown
timestamp: December 08, 2011, 11:53:20 pm
content: What are the steps to replicate your issue?Were you doing a "Probe Check" or something?What are the weird things and gibberish?I would assume a reboot or doing a Factory Default Setup would have solve it.

author: Rufus
author_rank: Super Contributor
timestamp: December 09, 2011, 01:07:15 am
content: Quote from: DaveDE on December 08, 2011, 10:31:16 pmThe compensation is the trimmer at the probe end. The trimmers at the BNC end are for high frequency compensation and not well documented. They won't produce any visible change on the scope's 1kHz cal signal.Best way I came up with to adjust them was to feed a fast (about 2ns edge) square wave into a BNC tee on one 50 ohm terminated channel with the probe into the other end of the tee and tweak for best waveform match.

author: DaveDE
author_rank: Newbie
timestamp: December 09, 2011, 06:09:20 pm
content: Thanks Rufus, I hadn't realized (or even noticed) the probe compensation trimmer on the probe end. That did the trick, and I can do the low frequency compensation now. I also am unable to reproduce the problem that caused me to have to reload the firmware. I apprently don't remember the exact key sequences I entered because I can't reproduce it. I did power cycle the unit before reloading the firmware and it did not fix the problem. The problem basically resulted in all of the waveforms looking choppy as opposed to smooth, kind of as if the the screen resolution was very poor. I also noticed that when I injected a square wave pulse train and then zoomed out on it, the pulses before and after the trigger were greatly attenuated.So anyway, the probe comp problem is no problem at all and I can't reproduce the scope going haywire so I'm not going to worry about it. False alarm I guess.

author: Rufus
author_rank: Super Contributor
timestamp: December 09, 2011, 07:52:20 pm
content: Quote from: DaveDE on December 09, 2011, 06:09:20 pmPlenty of people would be complaining if there was anything significant. Did you try the "Default Setup" button?

author: DaveDE
author_rank: Newbie
timestamp: December 09, 2011, 09:09:37 pm
content: No, I didn't try every option including the Default Setup. However, there definitely are a few minor issues going on with these scopes. I've noticed that every once in a while, waveform persist comes on out of nowhere, and the only way I can get rid of it is to hit the search button twice to clear it. I'm not complaining. It's no big deal and I'm sure Agilent will work it out with future firmware upgrades. Then again, it could be a Windows CE problem, but no matter.Agilent came out with these scopes as soon as they could with the thought that bugs will be flushed out by the users. Good for them, I know how that is. It's great that in this day and age most of these problems can be corrected with firmware upgrades as opposed to recalling units from the field.This scope is AMAZING though, I've been in this business for 35 years; a loyal TEK customer when it comes to scopes, but have to say Agilent really did a great job on this one, and they have their hand on the top knob of the bat at this point. What's really cool is that the software and features are the same on the lower bandwidth scopes as on the higher ones. To heck with bandwidth, I'm not going to pay twice as much to double bandwidth. I think most people would agree that all of the software feature advantages far outweigh bandwidth needs. I think the 200MHz scopes in this line is the sweet spot for price/performance.

author: DaveDE
author_rank: Newbie
timestamp: December 11, 2011, 12:29:29 am
content: I know what happened now, with regard to the scope losing its marbles, going haywire, etc. I just experienced the same problem when compensating probes again. I repowered the scope, still the same problem existed. While compensating a probe, the scope evidently invokes averaging, 8 averages, and does not always reset to zero averaging when done. That's why waveforms look bad after that. After I turned off averaging, everything is fine, no firmware upload needed. This is a software bug, and I hope Agilent will correct it.