EEVblog 1540 - The $80 Zotek ZT-702S Osciloscope Multimeter REVIEW

[EEVblog]

Is an $80 combo oscilloscope/multimeter any good? A look at the Zotech ZT-702S, with street price around US$60
https://s.click.aliexpress.com/e/_DFsZNAV

[Per Hansson]

It's really odd how the suppliers on Aliexpress etc does not have the name of the thing in the title of the page!
Like, how do they even come up with this title: "Digital Storage Oscilloscpe Multimeter Auto True RMS Tranistor Probe Multimetro 48M/S 10Mhz PC Waveform Digital Oscilloscope"
I guess writing "Zotech ZT-702S" would be too complicated   

[thm_w]

The point of the titles is to hit on as many key words as possible. But yeah leaving the name out is stupid, if I search google for it I can't find it at all.. maybe they'll fix it after its "released". As some kind of preventative measure in case they get a ton of bad reviews.

Zotech has responded in the youtube comments saying they'll fix some of the bugs. But no mention of the useless bargraph.

[abeyer]

So the verdict, eh...

Sounds like the most glowing review Dave's ever given a Chinese handheld scope. 

[wilfred]

So the verdict, eh...

Sounds like the most glowing review Dave's ever given a Chinese handheld scope. 

I thought so too. Makes me want to buy one. I got burned by Aliexpress on some cheap piece of test equipment a few years ago that Dave reviewed. Never did receive it and couldn't for the life of me work out how to get a refund. I haven't use Aliexpress since.

I do realise it isn't impossible to get refunds but I didn't manage it then.

[tunk]

Also sold as Richmeters 702S, so I guess it soon will show up as Anengs etc.:
https://www.aliexpress.com/item/1005005505224392.html

And wonder what the ZT-703S (2ch/250MSps/50MHz) will cost?

[RAPo]

And wonder what the ZT-703S (2ch/250MSps/50MHz) will cost?

I'm looking for it, but can't find it.

[SiliconWizard]

Ahah, it's pretty meh.
Still, we would have killed to get something like that at this price, 25 years ago.

[Fungus]

Ahah, it's pretty meh.

Compared to what at this price range?

[Kleinstein]

The DMM part is not that great, though still not as bad as the Habor freight ones. At least it looks like one has the USB interface available and a low voltage range is also not that bad - at least if it actially works and is not cheating on zero noise with a dead band. I would consider the DMM part more like an add on extra. The main point is the scope function. So don't compare to a $80 DMM - more like a $10 meter and $70 scope.
It is obvious that the CAT rating is not to be trusted - no real surprise on this. No idea why they add this obvious wrong rating, that could hurt exports to the EU.

From the video the scope part looks pretty decent for a portable one, though with a small screen.  Not sure if I would prefer a Fluke 123, which in a way higher price range.

[CChin254]

Could you please post high resolution photos of the PCB of this device?

[EEVblog]

It was very nice of Mr Li Hong himself to say thanks and invite me to visit if I'm over there 

[EEVblog]

Could you please post high resolution photos of the PCB of this device?

https://www.flickr.com/photos/eevblog/albums/72177720307943576

[bobale]

Can somebody please clarify something about this scope. In the specs it states it has 150V maximum input voltage. Does that mean it's 150V if the probe is in x1 mode? Does that mean it can be much higher if you switch it to x10? I need a scope to probe around switchmode PSUs, so 150V is not enough for that purpose.

[Kleinstein]

The voltage limit is a bit tricky. The actual amplifier input only sees the voltage after the probe division. Howeven when in AC coupled mode things depend on how the AC coupling is done. At least the switch has a good chance to also see the full voltage even with a x 10 probe. It is also likely that the coupling capacitor gets a higher (maybe all) voltage. Both the switch and the capacitor and maybe creep distances may not be made for a higher voltage.  A nasty surprise can also come from the charge stored in the coupling capacitor when switching to another voltage later - I once damages a scope input this way, going from some +150 V to some -150 V (or the other way around) with a scope that is good for some 200 or 250 V max.

There is another problem with using a not grounded scope with high voltage. Most of te normal probes are designed to work with a grounded scope and thus have no (good) isolation on the ground side. So one should at least check the probes manual, if they are OK to be used with a floating scope / ground.  It anyway needs extra care.

[LektroiD]

Does anyone know where the firmware update page is hosted?

Despite a couple of pitfalls (expected at this price range), it's a great little portable scope, very useful for my line of work. Thanks for the review, Dave!

[evlo]

This or Owon HDS242?

Does this have any advantage other than being 50usd cheaper? 10MHz/40MHz stands out.

[tunk]

The Owon has two channels, a bigger screen and it comes from a more reputable manufacturer.

Edit: A better comparison would be the not yet released 50MHz two channel ZT-703S.

[WI_Hedgehog]

It's really odd how the suppliers on Aliexpress etc does not have the name of the thing in the title of the page!
Like, how do they even come up with this title: "Digital Storage Oscilloscpe Multimeter Auto True RMS Tranistor Probe Multimetro 48M/S 10Mhz PC Waveform Digital Oscilloscope"
I guess writing "Zotech ZT-702S" would be too complicated   

The title has a limited number of available space, and/or the scope might be a clone/knockoff of the Zotech. It's common in that market to push the capabilities when the brand is perceived as not well known.

That Artery processor is a beast for such an affordable meter!

$60-$80 is a screamin' deal. No last-mode memory, but it is affordable! Love it for what it is!
"Doesn't this look smick?"--awesome line.
"Stop testing voltage in current mode."--awesome sticker! I want one!!!

[maelli]

Another small issue: Probe calibration depends on the attenuation.
Different for 2V or lower range to the 5V or higher range. (when the relay clicks)

How did I find out?
I happen to have a Tek 310A scope. This tube scope has a 100V 1kHz calibrator.

It is possible to calibrate the probe to be o.k. ish for both ranges, see
pic1.png 2volt range, undercompensated
piic2.png 5volt range, overcompensated

Good enough for a 80$ scope.

[Uniityy]

For those wanting to swap out the included 18650 cell for one of your own, it doesn't work with flat top 18650s by default.
I've modified mine by adding a little shim on the top connector so it makes good contact with my LG HG2 flat top. 2000mAh to 3000mAh in a little over a minute of work.
Pics here: https://imgur.com/a/WdQWFBR

[maelli]

quick follow up on the input capacitance.
Measured it with my LCR meter. 1kHz.
In the low voltage settings <=200mV/div @1:1, input capacitance of the scope is 9.2pF higher than in the high voltage ones >=500mV/div

[Shonky]

Has anyone seen any sign of the firmware update or binary image for these?

I have some ideas for essentially using the hardware but would like to see the firmware first.

[Sonny_Jim]

I bought one of these based on Daves review and for what I use it for (pinball machines), it's fine.  The one thing that sold me on it (and this will seem faintly ridiculous) was the fast continuity response which is great.  The screen is big and bright enough for it to sit in the corner of a pinball machine cabinet and still be easily read, although I haven't really used the scope functionality on it other than using it to check the output of some PIAs.  The only gripes I have are mostly the same as everybody else, the useless bar graph and it not remembering what mode you were in.

Pretty sure that comment about the 'we will supply updated firmware' was either a straight out lie or overly enthusiastic staff member as it should have surfaced by now.

[maelli]

another BUG: 500ns/div range is wrong. It is actually a 625ns/div range!
See picture showing a 1Mhz signal.
This one really needs a firmware bugfix.