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.

[Zebble]

There's a firmware update available.  Not sure what it fixes.  I've installed it succesfully, just haven't done any extensive testing.

https://zotektools.com/firmware-update/

[Shonky]

Looks semi encrypted. Well obfuscated at least as there are some repeating patterns that look like blank space.  Not very well encrypted if so.

[Harvey17]

There's a firmware update available.  Not sure what it fixes.  I've installed it succesfully, just haven't done any extensive testing.

https://zotektools.com/firmware-update/

What version is this? Mine came with v1.03.48

[RAPo]

v1.03.51

There's a firmware update available.  Not sure what it fixes.  I've installed it succesfully, just haven't done any extensive testing.

https://zotektools.com/firmware-update/

What version is this? Mine came with v1.03.48

[Lango1818]

I have just upgraded the firmware, not sure what it fixes either but will go and have a play. There is a short video on upgrading, and it was simple enough. After the upgrade it went from V1.03.48 to V1.03.51. Considering I paid $1500 for an analog basic scope in the late 80’s and $800 for my Siglent  SDS1104X-E scope this $100 dollar AU thing is far better than the 80’s scope and of course not a patch on the Siglent. I think it is great for a portable cheap scope or a beginners scope.

[rernexy]

Received mine today, bought from a guy named Ali of the Express shop. It has firmware version v1.03.55.

But the website (https://zotektools.com/firmware-update/) still seems to offer v1.03.51 based on the name of the file "ZOYI-702S-FW-V51(3).ZTK".

[kwass]

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.

The one just bought came with firmware 1.03.55.  It remembers the mode (o'scope vs multimeter) and all the settings within the o'scope mode between power cycles.  Multimeter mode always starts in DC volts after a power cycle but remembers all the settings (except min/max/avg) when switching to o'scope mode and back.  That it forgets the min/max/avg values when doing this is a plus, as it provides a way to resent those values (I don't think there is any other way to do that).

The multimeter functions are quite good.  It's got a low burden voltage on A [less than 0.1 Ohms sense resistor] and mA [about 2.4 Ohms] and although it's resolution is only down to 1uA; excellent 1uV and 10mOhm resolution too.  For $50 (what I paid on Aliexpress) is not that bad if it were just a multimeter.  My only grip is that for some reason you can't rel-out the value resistance measurements, but you can on everything else, this must be a bug.

[siealex]

My only grip is that for some reason you can't rel-out the value resistance measurements, but you can on everything else, this must be a bug.

Manually select the lowest range (or short the probes in auto mode), then short-press the power button. REL for resistance works only on the lowest range.

[kwass]

My only grip is that for some reason you can't rel-out the value resistance measurements, but you can on everything else, this must be a bug.

Manually select the lowest range (or short the probes in auto mode), then short-press the power button. REL for resistance works only on the lowest range.

Of course, you are correct, I don't why it wasn't working for me earlier. Thank you!

[tonyalbus]

New Firmware available 1.03.58 !!
https://zotektools.com/firmware-update/

Had the pleasure to play with the ZT-702S from Zotek directly,
As most noteced the firmware on the website was old 1.03.51 and newer devices came with 1.03.55
After my review i told my Zotek contact and they just updated to the latest on the website today
1.03.58 is ready for download.

The review


Have fun

[Razvan_N]

Are there some release notes? I could not find any on Zotek's website. What's new in this version of the firmware?

[tonyalbus]

Yes good one, i have asked, let see... if they profide it i will share it.
What improved in 1.03.55 was the it boots in the last mode DMM or Scope.
And the issue Dave had with the trigger bar not lining up was fixed in mine too... but i still have to try 1.03.58

[Razvan_N]

I really like this meter. Here are my favorite accessories so far: a BNC adapter and two neodymium magnets that keep the meter safely on a cabinet wall, car body or another magnetic surface.
The magnets are scavenged from 2.5" HDDs, are enclosed in heat shrinking tube and glued to the meter's tilt stand with Bison automotive double sided adhesive tape.
Very solid and also non-permanent in case I change my mind

[tonyalbus]

They have no release nots availble..

[kwass]

I upgraded from 1.03.55 to 1.03.58 and can't find any differences at all.  Also, after calibration I still find that the trigger level is slightly off.

[6gv5]

It's really odd how the suppliers on Aliexpress etc does not have the name of the thing in the title of the page!

This might be because over there brands come and go very quickly because they are nothing more than names. With some cheaper products the brand isn't even printed on the product itself, just on the box.
My idea - corrections welcome - is that the brand is perceived as more important in the western capitalistic world, so that they stick different ones to various products built in the same factories then see the ones becoming more successful and keep using them for other products too.

[Razvan_N]

I'm not sure if Zoyi techs read this forum, but I'd like to see two changes in future firmware
versions.

1. An option to disable key beeps. I like my meters quiet unless I'm doing continuity tests.

2. Displaying the real open leads voltage in diode mode (approx. 3 V), instead of ".OL V".
Showing "Overload" with the analog pointer at 100 looks a bit scary and it's not accurate,
as a 0.2 V Schottky moves the pointer to line 2 on the dial, as if the full scale would mean
10 V instead of 3 in reality.

[MLXXXp]

I upgraded from 1.03.55 to 1.03.58 and can't find any differences at all.

For one thing, waveform period (Prd) has been replaced with duty cycle (duty) in the "more measurements" display.

[rsjsouza]

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.

I didn't see this video at all until today, but coincidentally I got the ZT-702S model back in July and find it to be quite useful due to the same qualities you pointed out (with the same gripes as well). Also, the form factor, size and above average mechanical robustness are aspects that help me take it to the field more often.

When I got it, I put it in my toolbox for a roadtrip just for fun but not really considering it would be put to much use. We ended up having to make some things work on an el-cheapo car inverter and it proved quite useful to see if the 120V_AC "modified sinewave" was still good enough to power some of the more sensitive things tied to its output. Back from the trip I saw myself taking this unit to the field more often than my regular DMMs simply due to the practicality of having a "waveform observator" feature that gives extra insights to see noisy or failing DC power rails and follow audio paths.

Overall, a great surprise

[sparrow321]

just putting this here if anyone else was missing a updates version history:
from https://archive.is/3Kobd
version 1.03.51 download link is still live
version 1.03.58(current) download link

am still looking for a v55 download which seems from this forum and some to be the most stable

from what i gather v51 is the most stable functionaly.
on v58 a power on mode memory and duty-cycle meas was added but serious bugs with autorange and other bugs(look in YT video comments) were introduced

[5free]

@sparrow321
here it came from the official support .
CRC32: 41DF6B6A

[EEVblog]

There's a firmware update available.  Not sure what it fixes.  I've installed it succesfully, just haven't done any extensive testing.
https://zotektools.com/firmware-update/

Oops, I just bricked my 702S doing this update. I don't think my early unit was designed to be upgraded 

[Sonny_Jim]

It does say in the video that you can't update v1.03.30, which I guess was what you had.  For reference mine was v1.03.43 (ish, should have written it down)

Just commenting to say I'm quite happy they eventually released the firmware and if anyone needs to switch it back into English after an upgrade:

1.  Switch to multimeter mode
2.  Press menu
3.  Press F1

EDIT: Filename was "ZOYI-702S-FW-V58(1).ZTK" so I guess we are up to version 58 now.