What Oscilloscope buy?

[tautech]

Auto-cal can be disabled to avoid the problem in your video - to avoid the scope calibrating when you need it to capture a signal. If you disable auto-cal then the WRXi performs the same as any other non-LeCroy scope that doesn't have a similar auto-cal feature, and unless the temperature variations in your place are extreme (i.e. your lab was a garden shed in Alaska) then disabling it won't give you any problems (plus it will still occasionally calibrate i.e. if the temperature changes a lot, just less often). I'd give it a try.

Hmm
This implies when auto-cal is disabled the OS can stiil sense large temp changes and stiil auto-cal despite being disabled. Is that correct?
Is there a way auto-cal can be permanently disabled and self-cal performed manually at the users discretion ?

[Wuerstchenhund]

Auto-cal can be disabled to avoid the problem in your video - to avoid the scope calibrating when you need it to capture a signal. If you disable auto-cal then the WRXi performs the same as any other non-LeCroy scope that doesn't have a similar auto-cal feature, and unless the temperature variations in your place are extreme (i.e. your lab was a garden shed in Alaska) then disabling it won't give you any problems (plus it will still occasionally calibrate i.e. if the temperature changes a lot, just less often). I'd give it a try.

Hmm
This implies when auto-cal is disabled the OS can stiil sense large temp changes and stiil auto-cal despite being disabled. Is that correct?

Auto-cal is mostly hardware/firmware driven (Windows itself isn't aware of it), but yes, on those older X-Stream scopes there will still be auto-cal if there's a large temperature change.

Is there a way auto-cal can be permanently disabled and self-cal performed manually at the users discretion ?

That depends on the scope. On the non-Windows scopes (i.e. the old 9300 Series, the LC, the WaveRunner LT, the WavePro 900) if you disable auto-cal then it stays disabled, aside from a single calibration cycle after power-up.

On older X-Stream scopes (Windows scopes) like all WaveRunner 6k(A) and WavePro 7k(A)/WaveMaster 8k(A) produced before late 2008 auto-cal can't be fully disabled, and when set to disabled the scope will still do an occasional cal cycle if there's a large temperature change. Starting late 2008, due to user requests LeCroy made some changes to their acquisition system on WavePro 7kA and WM 8kA so that auto-cal could again be fully disabled. Since these were hardware changes they can't be retrofitted to older scopes unless you replace the acquisition modules, though, but for these older scopes they still offered the slight improvements that could be done through firmware updates.

There's not much use for having the user to start a self-calibration manually because he can't know when it's really required because he doesn't know the current status of the many parameters that go into that process. Don't forget that even the smallest/slowest scope variant (WR6k) comes with a 5GSps/10GSps acquisition system and up to 2GHz bandwidth, and WavePro and WaveMaster with a 10GSps/20GSps acquisition system and up to 5GHz bandwidth. It's oonly manual on low-end scopes because the acquisition system is simpler, the bandwidth lower and having a manual button is cheaper than implementing the sensors and processing the data necessary for proper auto-calibration.

As to when to switch auto-cal on or off, my recommendation would be that for a scope that is used stationary in a lab with somewhat stable temperatures auto-cal could easily be disabled. However, if the scope was moved a lot and used in different locations then I'd leave it enabled.

[joeqsmith]

No air pockets, the protective sheet just becomes comes loose and eventually falls off. It's a common problem with the particular touch panel used in the WRXi (it does not affect the WM or other LeCroy scopes, or the successor WRXi-A).

Wow!!  That would be real bad but expected after the knobs fell off. 

I mention cold start for a reason.    Until it warms up, seems you really want that auto cal on, and after it warms up, it's not a problem as it does not autocal very often.     

If I disable autocal under preferences, turn the DSO off, the next time it is turned on, autocal is enabled.   If the DSO is in auto trigger at the time it was turned off, it will run an autocal as soon as it boots.   If you then disable autocal, it will cal for each of the input range selections and or after several minutes after it has warmed up.   Expected. 

If it was in normal trigger when turned off, it will not run an auto cal on the next power up (assuming no input signal).     If normal trigger selected and it is powered up from cold, and then the autocal is turned off (so it has not yet ran a calibration), then let the system sit for 20 minutes.   So the units exhaust on right fan, center measures 43.3 with an ambient temperature (also starting temp) of 24.7.    At this time, no calibrations have been performed.   That is what I would consider a big temperature swing.   

More interesting, I then apply a signal for the first time from power up.  I would fully expect the system to run it's first cal.  But it does not!   It just runs along fine with no cal!!     Do you think the results are within spec with a 20 deg change in temp??

Now enable auto cal.   Again, still no calibration is performed.  DSO has been on now for almost 35 minutes! The exhaust temp is now 48.4 degrees! 

Now let's trigger it.  Bang, there's the cal. Very strange. Give it a try on your WP.     

[Mark_O]

After using that 64Xi for almost 6 months now as basically my main scope I have to admit, I like it!  Really, for a general purpose scope I like it a lot!

Wait!  What?     I thought this thing was a piece of crap, that you hated with a passion?     I remember you going on and on about how pathetically poor it was.      

Sounds like you've had a change of heart. 

The only thing that I don't care for is their calibration routine.   If you turn them on from a cold start and use them (fully expecting them to cal often) and select normal trigger.   The DSO will sit there and not run an auto cal.   Minutes go by, no auto cal.   Then you put in a signal, bang the auto cal starts and you may loose your signal.   ...   Maybe there is a work around so the thing will cal no matter if there is a trigger or not.

When you first turn them on, they do one auto-cal cycle.  Then, if there is no trigger, they will sit there indefinitely, and never auto-cal again.   No matter how much the temp shifts.     And the Channel sensitivity 'buttons' also sit there with question marks, saying "No data available".  Even though it knows damn well what the amplitude & offset settings are, because they pop up instantly the moment the first trigger is seen.     Basically, I'd consider these to be "initialization bugs", that skipped through the cracks.

The only "work around" I'm aware of is to hit the Auto-Trigger button just before powering down.  Then when you power back up later, it will run auto-Cal continuously as it warms up (because auto-trigger keeps firing).  And then, when you're ready to get busy, you can shift it back to Normal-Trigger mode, and be on your way.   

[joeqsmith]

Wait!  What?     I thought this thing was a piece of crap, that you hated with a passion?     I remember you going on and on about how pathetically poor it was.      

Sounds like you've had a change of heart. 

When you first turn them on, they do one auto-cal cycle. 

 

In my defence,  it was used and damaged when I received it.   The quote for repairs from the mfg was more than the DSO was worth.   Pulling it apart and seeing the connector for the damaged channel had already been replaced once (I posted a few pictures) and then hearing from Wuerstchenhund how it is a known problem.   The case construction is nothing near the quality I would expect from them and the case was already cracked in the corners.  Not to mention it was slow and would hang.

Then there was the whole knobs falling off of it...  The quality was poor at best and I NEVER would have guessed that 6 months later this DSO would still be running with the amount I have used it.   

So yes, added RAM, all new knobs and for some reason, re-seating the connector has solved the major problems.  Mind you NONE of these are anything I would EVER expect a LeCroy customer to have to deal with!   

That said, it's been solid (including the SSD swapout that was not supposed to work) and with those six long months of i not just sitting on a bench but being used and flawless operation,  yes I have had a change of heart about what I originally called the "whore-o-scope"          (... at least for home hobby use)

Interesting.  You state it will do an autocal on power up which is not what I wrote.

If it was in normal trigger when turned off, it will not run an auto cal on the next power up (assuming no input signal).

I ran this test again just to be sure and sure enough, it ran a single autocal with it powered up in normal and no input signal.   I must have missed it.

[Wuerstchenhund]

After using that 64Xi for almost 6 months now as basically my main scope I have to admit, I like it!  Really, for a general purpose scope I like it a lot!

Wait!  What?     I thought this thing was a piece of crap, that you hated with a passion?     I remember you going on and on about how pathetically poor it was.      

To Joe's defense the WR(M)Xi is a particular bad scope, at least in terms of the overall build quality (the actual performance/specs is top-notch, though). Mine didn't lose knobs but when I opened it for the first time I was pretty shocked how poor the overall build quality was, especially considering that this was a pretty expensive (lower) high end scope. I've never seen anything so shoddy from Agilent or any other big brand.

The thing with LeCroy is that they generally out-source the simpler parts of the design (i.e. chassis) to a manufacturing partner and focus on their core strength (the scope stuff, i.e. acquisition, front end and software), and unfortunately this particular Malaysian manufacturing partner (I couldn't find out its name yet) did a pretty poor job designing the chassis, and did an even worse job manufacturing it. Later WR(M)Xi models (IIRC end of 2007) where produced in the US and as far as I know resulted in a better build quality, although even those suffered from design flaws like delaminating screen protectors and broken carrying handles, or cracks in the plastics shell.

Having said that (and I guess it won't be long until the trolls arrive to call me names), it's a great scope if the particular scope had its connector problem and screen delamination fixed and is mostly sitting on a bench, as it's really a very advanced and capable instrument, even when compared with current high end scopes. There are tons of options available for it including serial decode for a large range of common and obscure protocols as well as a Spectrum Analyzer option (which turns it into a VSA), and all WRXi can be upgraded to MSO (WRMXi). Plus there are lots of probes available often at cheap prices.

No air pockets, the protective sheet just becomes comes loose and eventually falls off. It's a common problem with the particular touch panel used in the WRXi (it does not affect the WM or other LeCroy scopes, or the successor WRXi-A).

Wow!!  That would be real bad but expected after the knobs fell off. 

Indeed, but it was fixed pretty quickly (you mentioned your scope has been repaired before, maybe they also replaced the screen), and not every unit was affected anyways.

I mention cold start for a reason.    Until it warms up, seems you really want that auto cal on, and after it warms up, it's not a problem as it does not autocal very often.     

If I disable autocal under preferences, turn the DSO off, the next time it is turned on, autocal is enabled.   If the DSO is in auto trigger at the time it was turned off, it will run an autocal as soon as it boots.   If you then disable autocal, it will cal for each of the input range selections and or after several minutes after it has warmed up.   Expected. 

If it was in normal trigger when turned off, it will not run an auto cal on the next power up (assuming no input signal).     If normal trigger selected and it is powered up from cold, and then the autocal is turned off (so it has not yet ran a calibration), then let the system sit for 20 minutes.   So the units exhaust on right fan, center measures 43.3 with an ambient temperature (also starting temp) of 24.7.    At this time, no calibrations have been performed.   That is what I would consider a big temperature swing.   

More interesting, I then apply a signal for the first time from power up.  I would fully expect the system to run it's first cal.  But it does not!   It just runs along fine with no cal!!     Do you think the results are within spec with a 20 deg change in temp??

Now enable auto cal.   Again, still no calibration is performed.  DSO has been on now for almost 35 minutes! The exhaust temp is now 48.4 degrees! 

Now let's trigger it.  Bang, there's the cal. Very strange. Give it a try on your WP.

I'll do as soon as I get a chance (which considering current workloads might take a while).

BTW: my WRXi is now going to LeCroy for repair (I'm just sending in the Front End module and the acquisition board). We'll see how it goes.

[Mark_O]

In my defence,  it was used and damaged when I received it.   [long list of other grievances.]

Yes, I know.  I enjoyed following your tear-down and voyages along the way.

I was just pulling your leg.  Someone had to do it. 

[tautech]

In my defence,  it was used and damaged when I received it.   [long list of other grievances.]

Yes, I know.  I enjoyed following your tear-down and voyages along the way.

I was just pulling your leg.  Someone had to do it. 

Nice one Mark, you got 2 fish with one bait.