Author Topic: New Zoyi multimeter+oscilloscopes - ZT-70xS, up to 50MHz/250MSps (nov 2022)  (Read 52047 times)

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Offline Edmiri

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I have tried repositioning the probe leads and had no diference. I also tried reel mode and same results.
Strange why it didnt read at all when connected directly to the input terminals.
Also why it needs some minutes of usage before the capacitance value raise.  This is for both stock probe and Bside twezers. After it warmed up i read even 1pf capacitor using bside tweezers.
 

Online indman

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We should expect to have some measured C of the probe set, but certainly the reading will depend on how the lead wires cross over each other and how close the ends are to each other. It is perhaps possible that the 16pf set could read 45pf if the leads were arranged differently?
No,there won't be that much change in capacitance. Of course, it will vary in some limits from the position of wires in space, but such a capacitance of 45-50pF, which has tweezers, is unlikely to reach. I could be wrong of course, I just wanted to explain this effect with different probes, which observes Edmiri.

I have tried repositioning the probe leads and had no diference. I also tried reel mode and same results.
Strange why it didnt read at all when connected directly to the input terminals.
As I see from your last message, you still did not quite understand the meaning of what I was trying to show in my photos and in the message above. Perhaps because of my bad English? Sorry! Maybe someone else who understood what I wanted to say will explain it to you more clearly.
« Last Edit: March 21, 2024, 07:47:41 pm by indman »
 

Offline Edmiri

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You we're very clear.
What i don't understand is why when i directly connect the capacitor to the multimeter without any probe, it doesn't show any value. Larger than 33pf ca0acitors show value, so this means the connection is ok.
 

Online indman

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What i don't understand is why when i directly connect the capacitor to the multimeter without any probe, it doesn't show any value. Larger than 33pf ca0acitors show value, so this means the connection is ok.
Once again, I'll try to explain to you why this is the case. You see the numbers 00.000nF on the display of the ZT-703S with no capacitance connected. In reality, this is not the case. Imagine that now your device displays a conditionally negative value (-00.033nF). When you connect a 33pF capacitance directly to the input pins, this conditionally negative value is compensated and you can see that the display shows no change, i.e. it shows 00.000nF. If you connect another capacitance directly to the input jacks, e.g. 100pF, you should see a result of about 00.067nF on the display, i.e. 100pF-33pF=67pF.
« Last Edit: March 23, 2024, 07:07:32 am by indman »
 

Offline m72

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My observations.
The multimeter is a separate part of the circuit. The most common and widespread multimeter made on DTM0660/DTM1106. Therefore, any answers to the topic “how it works” and “what to do with it” can be found in topics about this chipset. There will be nothing new here. All the nuances, all the limitations stem from the capabilities of the DTM0660.
a) It can be calibrated at any time by recording what you need in I2C EEPROM. I remade the current shunt, calibrated it by writing down the settings at address 0x2A and got an “ideal meter for 4-20 mA”. In Russian it's "as easy as to send two bytes."
b) When switching to a multimeter, its mode will always be voltage measurement because no one bothers with maintaining the operating mode. Yes, in fact, this is unlikely to work out in this circuit design.
 

Online indman

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The multimeter is a separate part of the circuit. The most common and widespread multimeter made on DTM0660/DTM1106. Therefore, any answers to the topic “how it works” and “what to do with it” can be found in topics about this chipset. There will be nothing new here. All the nuances, all the limitations stem from the capabilities of the DTM0660.
The ZT-702S multimeter uses DM1109EN and EEPROM 24C02 chip. In the ZT-703S, the multimeter chip is still unknown since the markings have been erased and EEPROM 24C02. There are many similarities with the DTM0660, but there are also differences.

a) It can be calibrated at any time by recording what you need in I2C EEPROM. I remade the current shunt, calibrated it by writing down the settings at address 0x2A and got an “ideal meter for 4-20 mA”. In Russian it's "as easy as to send two bytes."
Not all calibration constants and configurations are stored in the I2C EEPROM, so for each device model the contents of the EEPROM will differ significantly. There are many things that are already pre-recorded at the factory into the main DM chip and their value cannot be changed or a special calibration procedure is required, which is known to the manufacturer!
« Last Edit: March 24, 2024, 06:58:45 am by indman »
 
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Offline MarkusWandel

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Firmware Versions and Bugs
« Reply #381 on: March 26, 2024, 06:42:51 pm »
This is odd.  The Zotek website offers v1.27, and that's what people seem to be generally talking about.  But the one I just got shows firmware 1.30.

Interesting bugs found so far:  While showing it to a friend, first the trigger position indicator disappeared.  Only the tiny green right arrow at the top right showed, but no amount of scrolling left and right brought the trigger position into view, and in fact, scroling was infinite since it kept wrapping around.

Shortly after that, the trigger mode button stopped working.  It was just stuck in "Auto", no way to go to single shot any more.  Toggling the unit off and on, and toggling between scope and multimeter mode, changed nothing.  Resetting the scope to defaults fixed it.

Also, shouldn't there be a way to change the scale/position settings for channel 2?  Selecting channel 2 in the menu affects nothing; the directional buttons still change channel 1.  The only way I've found is to disable channel 1 temporarily; then they access channel 2.

One hopes for active bug fix updates.  But again, why do I have newer firmware than what is downloadable?

Main dislike other than the issues above, is that the buttons need a pretty heavy press.
 

Offline ksxx

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Re: Firmware Versions and Bugs
« Reply #382 on: March 26, 2024, 06:54:37 pm »
Also, shouldn't there be a way to change the scale/position settings for channel 2?  Selecting channel 2 in the menu affects nothing; the directional buttons still change channel 1.  The only way I've found is to disable channel 1 temporarily; then they access channel 2.

This sounds annoying... Will receive mine in the next few days. I will most likely use only 1 channel 95% of the time. What can we expect for around 80€ only? Lets see if we get more FW updates or if Zoyi rather releases a new scopemeter model.
 

Offline MarkusWandel

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Another question, is everybody's ZT703s as noisy as this one?  Probe clipped to the calibrator output/ground lug, default square wave output, haven't messed with the calibration screws yet.

About 2-3 pixels of noise regardless of the vertical scale.  Even with the probe grounded, at some vertical scales about 2 pixels of noise are present as in the last screenshot; at others the line is flat.  Par for the course at this price level?
 

Offline Hoggy

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Another question, is everybody's ZT703s as noisy as this one?  Probe clipped to the calibrator output/ground lug, default square wave output, haven't messed with the calibration screws yet.

About 2-3 pixels of noise regardless of the vertical scale.  Even with the probe grounded, at some vertical scales about 2 pixels of noise are present as in the last screenshot; at others the line is flat.  Par for the course at this price level?


I've noticed the same thing - and was wondering if it was just me...

My 3 cheapie ZeeWeii scopes don't show this much noise.
 

Online Mortymore

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Glad that they don't show perfect lines, as they seem to show perfect zeros on multimeter, to make some users happy  :palm:

 
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Online indman

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Glad that they don't show perfect lines, as they seem to show perfect zeros on multimeter, to make some users happy  :palm:
Bingo,you think right! Beware if you see a straight, nice and noiseless sweep line on digital oscilloscopes, as well as absolute zeros on the display when measuring capacitance! ;)
 
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Offline MarkusWandel

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Next one:  I haven't found a way to display absolute voltages for the horizontal cursors; it only displays a delta.

As long as the voltage graticule is accurate (with the channel zero point arrow lined up visually) one can just place one cursor on, say, 0V and then read the absolute voltage for the other off the delta.  But  have I missed something?
 

Offline MarkusWandel

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Beware if you see straight lines on cheap oscilloscope that is.  My previous experience with a digital scope, when I was still doing that sort of analog lab work, 30 years ago, was with a HP 54100.  And that one really did give clean lines - at higher pixel resolution too - for DC values.
 

Offline MarkusWandel

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Watched the video above.  Admittedly all the work with the old expensive early generation digital 'scope was in single-shot mode.  And I don't have any screenshots left (hardcopy in those days - you hooked up a printer via HPIB) to really confirm that my memory is accurate.
 

Offline Fungus

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Next one:  I haven't found a way to display absolute voltages for the horizontal cursors; it only displays a delta.

As long as the voltage graticule is accurate (with the channel zero point arrow lined up visually) one can just place one cursor on, say, 0V and then read the absolute voltage for the other off the delta.  But  have I missed something?

STOP it then use the trigger level as a "cursor".
 

Offline MarkusWandel

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Is this more "don't expect too much from a cheap scope" stuff?  I clipped both the probes (P2060) to the calibrator lug - and the ground clips to the ground lug - to finally adjust the compensation screws.  Nice and rectangular, but... different amplitude?  I figured OK, cheap probes, don't exactly do 10:1 attenuation (both were switched to 10X).  But swapping the BNC connections didn't change anything.  Channel 2 still shows the same, lesser amplitude.
 

Offline wasedadoc

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Is this more "don't expect too much from a cheap scope" stuff?  I clipped both the probes (P2060) to the calibrator lug - and the ground clips to the ground lug - to finally adjust the compensation screws.  Nice and rectangular, but... different amplitude?  I figured OK, cheap probes, don't exactly do 10:1 attenuation (both were switched to 10X).  But swapping the BNC connections didn't change anything.  Channel 2 still shows the same, lesser amplitude.
If you have not done so already, try doing the calibration.
 

Online kloetpatra

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It looks like new stock is sold with 1.3.0 Firmware. However it is still nowhere to be found online.
« Last Edit: Today at 10:06:24 am by kloetpatra »
 


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