Weird pattern when I added 3rd channel on 4423 scope

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Weird pattern when I added 3rd channel on 4423 scope

Postby hexibot43 » Thu Jun 14, 2012 7:47 pm

I've included two snapshots that will probably better explain what has me scratching my head more than anything else.

Here is the scope showing me a good patterns just moments before I add the third channel.
GoodReading2channelsinuse.JPG
Looking Good


Now here is what happens once I add the third channel?
After3rdChanneladded.JPG
What the Hay???


I tried removing it and everything looked good with the 2 channels again. As soon as I turned on the 3rd channel right back to this odd pattern. Am I doing something wrong. I didn't change any of the settings beside adding the third channel. This was using software version 6.6.23.2

I was wondering if there might be a firmware update to my scope or something else that could be effecting things. I am currently running Firmware 1.0.5.0/0.6.12.0.

..........

I just started from scratch and loaded each channel one at a time and now it is working. So it must be something I'm doing....any ideas?

Thanks,

Marcello
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Re: Weird pattern when I added 3rd channel on 4423 scope

Postby hexibot43 » Thu Jun 14, 2012 9:29 pm

Just installed 6.7 and it not only worked with 3 channels well but a 4TH as well.

AfterRepairs4runner.JPG


So I guess it might have been just software. Been using my scope more lately and I swear half the time I need at least three channels. I still had the software freeze a copy times, and once had to actually reboot power cycle the scope as well to get things back up and running. But so far much better with 6.7.


Thanks,

Marcello
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Re: Weird pattern when I added 3rd channel on 4423 scope

Postby Robski » Thu Jun 14, 2012 9:31 pm

what are you AC coupling to & why ?
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Re: Weird pattern when I added 3rd channel on 4423 scope

Postby taho » Thu Jun 14, 2012 10:44 pm

hexibot43 wrote:...I tried removing it and everything looked good with the 2 channels again. As soon as I turned on the 3rd channel right back to this odd pattern. Am I doing something wrong. I didn't change any of the settings beside adding the third channel. This was using software version 6.6.23.2
..........
I just started from scratch and loaded each channel one at a time and now it is working. So it must be something I'm doing....any ideas?


Hello!
I think a problem of distortion of signals disappears in bad connection of grounding of channels A and B. At connection of third channel C channel grounding gets not on car grounding, and on other strong signal and thus brings distortions at measurement (the measured signal is modulated). It is necessary to be attentive in connection to the car of several channels not to close through grounding 4423 among themselves electric schemes of the car.... :!:
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Re: Weird pattern when I added 3rd channel on 4423 scope

Postby hexibot43 » Fri Jun 15, 2012 3:24 pm

I think I understand what you are saying. Honestly, I changed nothing with connections and was able just by using the 6.7 software to no longer see the problem. When I said I started from scratch - I meant in software. I restarted the software, and added each channel instead of starting from 2 channels as they were set up in my presets. I had the shield grounds of all channels tied together and what I thought was a good engine block ground, but I am going to try hooking it up again and remove the ground to see if I can recreate what I am seeing.
I am amazed at how easy it is to not have things set up right. Or inadvertently inducing bad data into the signal path.

The "Modulation" of the measured signal - What does it tell you???

Would you usually think this to be in the signal path?

I'm guessing if I see this again I should be looking at my grounds more carefully. I did only have a single ground point for all channels. You've got me thinking of making a new adapter cable with multiple points for redundant grounds. I'm so worried of damaging the scope with unmatched grounds. I quickly tie the grounds together externally to ensure I don't goof and damage the internals of the scope.

I just started using math channels to use two channels together for a floating ground issue, and that worked very well. Looking forward to see what else they'd do in software.
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Re: Weird pattern when I added 3rd channel on 4423 scope

Postby taho » Sun Jun 17, 2012 2:02 am

The "Modulation" of the measured signal - What does it tell you???


Signal measurement rather "-" car (grounding) meant not, and for example measurements concerning other signal or not earthed wire on which are directed electromagnetic hindrances...
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Re: Weird pattern when I added 3rd channel on 4423 scope

Postby hexibot43 » Tue Oct 23, 2012 10:17 pm

I wanted to post an update to my problems when I would want to use more than two traces. I started having this problem again today. Checked my grounds, added a couple redundant grounds. Still had problem. I suddenly started getting these "checking Usb Cable" messages popping up. Go back to 2 traces and problem gone. As long as I pick no more than 2 traces everything worked well. I was running an IBM T43 laptop to run the software. I switched it out for a T60 running windows 7 today, and now everything is rock solid. So I'm guessing with the 3rd trace I was pumping just enough info over the usb, and that was when I'd see these glitches. Cannot confirm this but there was obviously a problem with the USB portion of the system. New laptop no more glitches. I bet I could have just added a pcmia usb card, but when I had the T60 just sitting here I figured I'd grab it before my boss found something to use it for. Hope this helps someone.

Thanks,

Mab
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Re: Weird pattern when I added 3rd channel on 4423 scope

Postby joshua1 » Thu Oct 25, 2012 12:01 pm

Hi,
Thanks for the useful information along with graphical representation............The graphical representation gives a clear view regarding the topic...........
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