Why do Tek TDS210 Scopes sell for so much on Ebay?

[bdunham7]

I might sound like a drama queen

You sound like an inexperienced user.  The situations sounds like PEBKAC (user error).  How would you go about setting up your SDS1102CML+ to capture the turn-on event?

[flashcoder]

You mean enable single more, make sure there is no bandwith limit on and set the trigger on the rising edge? Yes I did that. I did the same steps as I did on TDS210 which worked at the first try whereas SIGLENT simply did not capture anything. I tried to see if I can spot an impulse on the screen without triggering but it never showed the impulse..

[xrunner]

You mean enable single more, make sure there is no bandwith limit on and set the trigger on the rising edge? Yes I did that. I did the same steps as I did on TDS210 which worked at the first try whereas SIGLENT simply did not capture anything. I tried to see if I can spot an impulse on the screen without triggering but it never showed the impulse..

I have a TDS210 up on the shelf. If you know what the pulse characteristics are I would have tried to duplicate the triggering here with a pulse grnerator, but I don't have the Siglent model to compare so it wouldn't prove anything. Maybe someone else here can try it ... 

[bdunham7]

You mean enable single more, make sure there is no bandwith limit on and set the trigger on the rising edge? Yes I did that. I did the same steps as I did on TDS210 which worked at the first try whereas SIGLENT simply did not capture anything. I tried to see if I can spot an impulse on the screen without triggering but it never showed the impulse..

OK, so what were the characteristics of the impulse as shown by the TDS210?  It seems wildly improbable that there is either a bug  or single-unit defect in the Siglent that would prevent capturing such a seemingly basic event but not be readily apparent in other cases.  There are two additional settings that you should have mentioned in your setup, b/t/w.  Actually three, but unless you actively changed something the third should be correct by default.

[tautech]

No the SIGLENT is not damaged, it is not much used and even looks brand new, so far it always did what I wanted. Like I said I had no complaints before and I would probably not have any if not this incident. It is SDS1102CML+ model. Yes it is entry level scope but this topic discussion is about the fact that the newer cheaper scopes are always better. And this is clear example that it isnt true. It does not register the impulse no matter what. I did set it to defaults to rule out any setup mistakes but it does not "see" that short impulse. But the old and omg_why_it_is_still_so_expensive TDS210 shows the signal flawlessly. That was my point. I cant trust this Siglent any more. What other stuff it could be not doing correctly? Well obviously this is a simple case but how can I be sure that it always "sees" the stuff that I am trying measure? I might sound like a drama queen and this is not life and death situation but all I am saying it is better to have an older instrument that you can trust instead of having a nice color screen.

BS
Did you use Normal or Single triggering ?

[bdunham7]

BS
Did you use Normal or Single triggering ?

Well, actually either of those should work unless the trigger is down in the noise, in which case neither will work.  It's the default AUTO setting that would cause trouble.

[flashcoder]

OK, so what were the characteristics of the impulse as shown by the TDS210?  It seems wildly improbable that there is either a bug  or single-unit defect in the Siglent that would prevent capturing such a seemingly basic event but not be readily apparent in other cases.  There are two additional settings that you should have mentioned in your setup, b/t/w.  Actually three, but unless you actively changed something the third should be correct by default.

Well I was wildly surprised myself. Initially I thought it is the signal hunting glitch that its the triggering that fails, that their advertised "easy signal hunting" feature is the problem but I tried to spot the impulse without any triggering multiple times and I never saw any change on the screen, it just skipped it like its too fast for it to notice. If I understand correctly if the waveform does not "jump up" on the screen then scope simply does not not see it, there is nothing to trigger on. So it means the triggering is not the problem it is the front stage. And what are those other settings I should have mentioned in scope setup? I just gave the basic ones, sure the trigger level is important etc etc but what surprised me is that I never saw the impulse w/o any triggers just by looking at the screen at high frequency and try to spot anything..
I might recreate the whole scenario because I did not fix that TV yet I drove it off to my storage maybe will look at it someday again and repeat the measurements. Maybe I am doing something wrong, I am not a very experienced indeed in these type of repairs.

If we will find out that it was my mistake then that itslef in an answer why these old TDS210 scopes sell for so much on eBay - because not just EEVBlog experts can operate them but normal people too!

[bdunham7]

Well if you do get the TV back in, post here and we'll get you that capture.

It is true to some extent that a scope like the TDS210 is probably more foolproof then the SDS1102CML+, but there should be no issue capturing this signal.  To start, you should have a rough estimation of what the signal might look like.  You mentioned a brief blink, so an overall event length from tens to hundreds of milliseconds seems likely.  Obviously the power-off signal level is zero, lets say the power on level is 10 volts.  That's just a guess, if at first you don't succeed, try again.  So, as you said, you set the scope for single mode, trigger to rising edge and obviously, volts per division to a reasonable number, probably 5.00V/div.  Then, in addition, you have to set the timebase to something on the order of the anticipated signal, so perhaps 10ms/div to start and you have to set the trigger somewhere between zero and the maximum you expect.  I would set it at 1 volt or so, but anything high enough to keep noise from triggering it will work.  The third thing is that the input should be DC-coupled, not AC.

If you set the timebase very fast, you'll likely see nothing.  You certainly won't catch or observe a one-time event like that unless you use a very slow sweep or roll mode with peak detect, if the CML+ has it.  And when you use single mode, if you leave the trigger near zero, random noise may trigger the capture before the event occurs.  I don't have a CML+, but on most scopes there is an indication of whether it is ready (ARMED) or has already triggered (TRIG).  You need to make sure it stays armed without triggering until your power-on even occurs.  Anyway, better luck next time!

b/t/w, I have no idea what "Easy Signal Hunting" is?

[tautech]

One must remember early DSO's emulated CRO performance and particularly phosphor persistence whereas later other tools were added to DSO's to do the same thing....user selectable Persistence and color grading for example. 
As WFPS rates increased CRO emulation was counterproductive and waveform info pushed to the display became only the real data points and somewhat simple user input required to reliably show glitches, pulses and the like.

It's a long time since I had a TDS210 when at the same time a TDS2012B was my main DSO yet of the many dozens of SDS1102CNL and + models sold no one has ever complained they couldn't detect a pulse or glitch.
How you understand your DSO and how you apply its feature set is what's important.

b/t/w, I have no idea what "Easy Signal Hunting" is?

Marketing slogan. 

[2N3055]

First make sure you set input channel to DC coupling, and also trigger to DC coupling.

When hunting for such, very undefined pulses, a peak detect plus roll (scan) mode is very helpful.
Roll (scan) is slow, untriggered mode that basically emulates chart recorder.
That, combined with peak detect mode of acquisition, creates a slow scanning graph of voltage that will, despite being slow, capture high peaks in full bandwidth of the scope.
Since roll mode is slow, you simply enable it, let it scan, manually create event to measure, and than you have time to quickly stop the scope manually too.
Your fast pulse might be a singe vertical line on the screen, but it will be there, and it will have proper amplitude.
If needed, now you know how to setup scope vertical sensitivity, and then you set trigger to  Edge mode, and set trigger level to somewhere mid way of the signal. You than switch from ROLL mode to normal swept mode, and set some time base that looks logical from what you see on the screen. Keep the peak detect mode still, until you manage to find timebase that shows your signal nicely. 

You can get pulse captures in Single and Normal trigger mode if triggering is set right. Auto trigger mode is not good because after some timeout it will erase the screen and do capture on it's own if there was no trigger for some time.. Single mode will capture and stop and Normal mode will capture, rearm and wait for next one. If you want to keep just one capture then you use Single, obviously.

On scopes that have ETS sample mode (equivalent time sampling), you have to make sure your'e NOT using ETS on pulses. It works on repetitive signals only, and on single pulse you will get nothing on the screen.

It is amazing, how very simple scopes like that, that have only few more options than old TDS210, quickly become more complicated to use...
I don't have (and never used) that particular Siglent, so I don't know if firmware is clever enough to automatically disable ETS when you enter Single mode.