OWON HDS 200 Handheld Oscilloscope w/ builtin DMM/AWG

[MrAl]

I bought it from the local dealer in my country, with his warranty seal.

Hi,

Oh ok, well i suspect then that you got a unit that was sitting around for some time before it was sold and the firmware was never upgraded.  I was wondering if you upgraded the firmware would it have worked better.

This brings up the question of how do you recommend a scope that may be the very same model but has different firmware.  If they get an old unit it may not be very good, but if they get a newer unit it may work acceptably well.

[MrAl]

Recently bought an HDS2102S. S/N is 22520073 and F/W is V4.1.0.

Hi,

Maybe you could check and see if you have that serious drift issue with yours.  If so, maybe look into upgrading the firmware if that is possible.
See if you can find "calibration" on any of the menus.

[orb]

I bought it from the local dealer in my country, with his warranty seal.

Hi,

Oh ok, well i suspect then that you got a unit that was sitting around for some time before it was sold and the firmware was never upgraded.  I was wondering if you upgraded the firmware would it have worked better.

This brings up the question of how do you recommend a scope that may be the very same model but has different firmware.  If they get an old unit it may not be very good, but if they get a newer unit it may work acceptably well.

You're right, however the voltage drift seems to be related more to the hardware. The firmware update may fail (in the worst case = brick), then the service could say that "I broke the device". They know what firmware version is installed on the hds242 they sell.

By asking, I'm trying to determine if more devices have the same problem. So far I've found out that two hds242 units (hw:v2.1 & fw:v7.2.0) also have a problem with significant voltage drift while warming up. It was mentioned by @RogerG, we spoke via pm.

In conclusion: "we have" three hds242 & one hds272s with this issue. Three of them have hw: v2.1 (mine hw version has a status: "unknown").

[RogerG]

@orb:
Sad to read that...
Did you ask for a complete refund or a replacement?

[simple]

This is my unit with the latest v8 software

[orb]

@RogerG

I asked for a replacement, because it is useful tool for me.

[RogerG]

@orb
Ok, then I'm curios about the DC drift at the replaced device 

[orb]

Ok, I'll let you know what next.

[orb]

This is my unit with the latest v8 software

Try to calibrate it after 1h of working, then turn it off & "cool down" for about 3-4h, then power on, press "auto" button. Show us scale "10V/div; 1 ms/div", and the values: mean/min/max (of course for DC).
Turn off the flash, please.

[tly]

Hi all.
It seems I have to update "the bugs list". 
I checked @funky303 and @orb posts... and Voilà! ... video incoming.

I wonder if Owon is opened to update the firmware for older units too.

[funky303]

https://youtu.be/sPwjugw7fac
CH1 short to ground...
it is more like a random generator. you can shift y, until your preferred voltage is shown.
Min,Max is strange too.
offset is just the bug indicator, the problem is more fundamental in the software. (v8.0.1)

[tly]

If you observe any bug: please add in your comment time marker (video position).

Video (no sound):
00:00 -> 02:05 device reset: default & autocalibration
02:05 -> 09:20 tests with channel 1 set to GND and channel 2 OFF.
09:20 -> 14:10 tests using channel 1 set to AC using SG (sine/10MHz/4Vpp).
14:10 -> 17:48 a few other tests.

Video Link

[funky303]

I agree with you.  Of course, sorry.
Constant 0 V is expected in V with a short-circuited input.  Regardless of the vert. shift.  However, V is not constant and varies with Y displacement.  With this behavior, you don't have to worry about temperature-dependent offsets.

 I thought a time marker was unnecessary because it affects the whole video. 

Attempting an explanation:
 If the acuracy related to the y-axis in the display area is 8 bits, then we have 10V/div x 8 div = 80V.  And 80V / 256 = 0.3125V as quatization.  With +1Lsb Toggle (due to bad calibration), Vmean can of course now wobble between 0...0.3125V on average (calculated as a float).  As observed.... But then Vmin = 0 and Vmax = 0.3125V would need to be.  But it is not.

Maybe someone has an explanation and it's not a bug but an unqualified expectation on my part...

[orb]

If you observe any bug: please add in your comment time marker (video position).

Hi. Could you please put this video on the yt? I am not able to download 2GB video on my mobile network.

[tly]

Hi. Could you please put this video on the yt?

Video is posted on google drive - all options and speed are like on youtube.
The difference: is not publicly available unless you have the link.

[orb]

Video is posted on google drive - all options and speed are like on youtube.

Ok, it works, thanks. I rarely use gdrive for videos, so I forgot some features.

[orb]

@orb
Ok, then I'm curios about the DC drift at the replaced device 

Finally I got a refund, because they don't have hds242 for a replacement.

I found another store. I don't know whether to buy hds242(s) again or maybe hds272(s)? Now I'm more skeptical about these devices, but I need something portable.

[RogerG]

Since the sample rate of 242 and 272 are identical, I can't see any advantage of the 272.

The function generator is rather limited in its output level, you gave to decide if it's sufficient for you.

[MrAl]

Since the sample rate of 242 and 272 are identical, I can't see any advantage of the 272.

The function generator is rather limited in its output level, you gave to decide if it's sufficient for you.

Hi,

Doesnt the 272 have higher bandwidth?  I thought the 242 was said to be 40MHz and the 272 was said to be 70MHz.

[RogerG]

Sample rate <> bandwidth

[orb]

@RogerG

You are right about what you wrote. I'm just wondering if maybe the build quality in the higher models is a bit better. Although the video on youtube showed that even the hds272 has a problem with voltage drift.

[RogerG]

In my opinion it may have to do with the 25% overclocked a/d converter. So the 2102 with its doubled sample rate is IMHO the first candidate for a - maybe - better build quality. Not the 272.

[MrAl]

Sample rate <> bandwidth

Hi there,

Are you trying to say that sample rate is not equal to bandwidth?
I dont think anyone said it was did they?

[knave]

Thoughts on using this for automotive?

Maybe a lesser model?

I want something "good enough" to check DRL circuits and robust enough it could withstand a drop or two inside the engine bay.

I don't want to drag an expensive mains powered scope over to struggle and then damage it.

[RogerG]

Sample rate <> bandwidth

Hi there,

Are you trying to say that sample rate is not equal to bandwidth?
I dont think anyone said it was did they?

I tried to say that you don't have an real advantage on buying the 272 because its sample rate is equal to the 242. And this sample rate is just hardly enough to cover 40MHz. This can be seen when looking on more demanding waveforms than sinus. With a 70MHz sinus wave even the 242 doesn't struggle when using proper probes.