Author Topic: EEVblog 121GW Multimeter Issues  (Read 125208 times)

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Online rattnallen

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Re: EEVblog 121GW Multimeter Issues
« Reply #750 on: November 22, 2018, 01:18:14 am »
Firmware version 1.57 at https://www.eevblog.com/product/121gw/
The manual is still not updated ...
 

Offline CDaniel

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Re: EEVblog 121GW Multimeter Issues
« Reply #751 on: November 23, 2018, 09:16:00 am »
It is very good that now we have improved capacitance mode .

But I can't understand how a team of profesional coders make a software and not check the basics - now in manual mode is not showing "overrange" , the display just freeze or show 0.000 .

Autoranging an 100uF capacitor is going into 10.00mF range so you see only 2 digits , 97uF for exemple .
10nF , 100nF , 1uF , 10uF seems to be fine ...

Other issues not corrected yet ...
In resistance mode , the autorange hysteresis is way too big , switch in upper range at 55000 counts but down at 40000 counts . So , as the resistance ranges switch from high to low resistance , a 470ohm resistor is showing 0.4700 in 5K range not at full resolution in 500ohm range as should be .

In voltage mode hysteresis is too big also .
This cause problems when measuring something in between , loss of resolution when measuring variable or adjustable voltages .
For a 50.000 counts multimeter I think it is normal to switch at 55.000 counts up and probably at 51.000 down , to have 50.000 counts all the time . And 5V is the most used voltage in electronics ... this value should never be in hysteresis


Edit
Interesting , when measuring capacitors in manual range is showing overrange if the capacitor is not too big , so in 10nF range is showing overrange for 100nF but just freeze for 10uF ...
« Last Edit: November 23, 2018, 09:46:12 am by CDaniel »
 

Offline 1anX

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Re: EEVblog 121GW Multimeter Issues
« Reply #752 on: November 23, 2018, 01:26:51 pm »
Edit
Interesting , when measuring capacitors in manual range is showing overrange if the capacitor is not too big , so in 10nF range is showing overrange for 100nF but just freeze for 10uF ...

Confirmed

Sheesh, two EEVBlog engineers and an instrument manufacturer like UEI, you would think they would have a test procedure worked out for firmware revisions by now!

If Dave was reviewing this meter and its updates on EEVBlog it would rate the dreaded FAIL conclusion.

If Dave is looking to bring out a version 2 of this meter, the thing needing change the most would be their testing procedures because at the moment its not professional.

My verdict is that the 121GW has potential, but is hampered by the driving force behind it, namely Dave being more interested in releasing regular blogs than fixing the meters problems.

I own one of these meters and am looking forward to the good faith shown by supporting the kickstarter being returned by proper quality checks and testing. Its so close, but still so far from being a great meter!
 
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Offline CDaniel

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Re: EEVblog 121GW Multimeter Issues
« Reply #753 on: November 23, 2018, 06:16:09 pm »
Now there are some warning beeps when auto power off timer is about to expire , this is a nice thing .
« Last Edit: November 23, 2018, 06:27:17 pm by CDaniel »
 

Offline dr.diesel

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Re: EEVblog 121GW Multimeter Issues
« Reply #754 on: November 28, 2018, 05:32:59 am »
I suspect this has already been noted, and perhaps a hardware limitation, but manual range is lost after APO and back on again.

As of v1.57

Offline n3mmr

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Re: EEVblog 121GW Multimeter Issues
« Reply #755 on: December 01, 2018, 01:11:43 am »
A minor issue with the manual: it doesn't talk you thru the idiot startup phase you have with  any new piece of gear.
Make sure meter is off.
Open it
Batteries in
Reattach the back
Turn the rotary switch to V
Display will show "U- FWversion", like "U- 1.54" for FW v 1.54.
.....

A minor tech issue with the meter:
I would have liked an AC DC mode where main display shows V DC and secondary display shows V AC.

Kudos for the meter being useful, albeit not too accurate, up to at least 40kHz for sub-1V voltage.
 

Offline nonentity

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Re: EEVblog 121GW Multimeter Issues
« Reply #756 on: December 04, 2018, 07:01:48 am »
Nanofarad values of capacitance yield readings of zero with nanofarad manual ranging.  Occasionally an incorrect low value for a capacitance is displayed which then very slowly increases over a ~30 minute period up to the correct value.
Also the Logging/Bluetooth value for the nonofarad capacitance is 10 times what it should be.

Using 121GW meter recently purchased from Welectron with V1.57 firmware.
iPhone bluetooth app version: build 1.78
Problem is reproduced by:
1.) Attach 0.14 nf cap                            [edited 4 Dec 2018]
2.) Turn on meter, select capacitance
3.) Set mode to capacitance - the correct value usually displays.
4.) Cycle through mode selection and ranges once or twice.
5.) The capacitance shows zero in both nonfarad ranges or an incorrect slowly increasing value toward the correct value.

Slowcap1 shows the initial Log file.
Slowcap2 shows Log file after about 20 minutes.
« Last Edit: December 05, 2018, 03:54:56 pm by nonentity »
 

Offline lowimpedance

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Re: EEVblog 121GW Multimeter Issues
« Reply #757 on: December 04, 2018, 09:26:15 am »
There was some discussion that had started in relation to this over in the firmware detail thread, that discussion morphed somewhat but to preserve that detail it stayed in that thread.
If there is a way for the 'moderators' to move the relevant posts here that would be better than diluting the other threads intent.
The odd multimeter or 2 or 3 or 4...or........can't remember !.
 

Offline nonentity

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Re: EEVblog 121GW Multimeter Issues
« Reply #758 on: December 04, 2018, 11:07:47 am »
I agree.  This is the issues thread.  The other thread is for something else.
 

Offline Seppy

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Re: EEVblog 121GW Multimeter Issues
« Reply #759 on: December 04, 2018, 02:04:28 pm »
Nanofarad values of capacitance yield readings of zero with nanofarad manual ranging.  Occasionally an incorrect low value for a capacitance is displayed which then very slowly increases over a ~30 minute period up to the correct value.
Also the Logging/Bluetooth value for the nonofarad capacitance is 10 times what it should be.

Using 121GW meter recently purchased from Welectron with V1.57 firmware.
iPhone bluetooth app version: build 1.78
Problem is reproduced by:
1.) Attach .014NF cap
2.) Turn on meter, select capacitance
3.) Set mode to capacitance the correct value usually displays.
4.) Cycle through mode selection and ranges once or twice.
5.) The capacitance shows zero in both nonfarad ranges or an incorrect slowly increasing value toward the correct value.

Slowcap1 shows the initial Log file.
Slowcap2 shows Log file after about 20 minutes.

The resolution of the capacitance is 0.01 nF, unless I've misunderstood you might be using it for values out of the meters range.

Regarding the app, an update hasn't yet been released to add support for the additional capacitance ranges (there is a note on the 121GW firmware page)
"NOTE: This version has a change that will not function correctly with the app in capacitance range. An update to the app will be released soon."
« Last Edit: December 04, 2018, 02:12:32 pm by Seppy »
 
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Offline Seppy

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Re: EEVblog 121GW Multimeter Issues
« Reply #760 on: December 04, 2018, 02:38:16 pm »
Hello EEVBlog!
I feel honored to now be a part of this awesome community. What makes me very sad is that my first post has to be a negative one.

I purchased my 121GW meter on July 26th 2018, during a small batch at official EEVBlog store, after being informed about its availability by the newsletter. Soon I discovered how big mistake I have made.

After receiving the meter and unboxing it, few things immediately stood out. The meter was scratched in many places (especially the knob and in the area around lead sockets) - see attachment. Scratches on two flat sides of the knob clearly came from someone's else fingernails. Part of the knob you grab by your fingers was noticably shinier than other areas. Batteries have also already been put inside the meter - From what I've seen on unboxing videos, these should be included seperately in the pouch.  Conclusion is simple - I recieved a used meter. I thought - "Ok, fine. This is not that bad. I can use this meter nevertheless." And I could - for a month. After that strange things started to happen.

Before making the purchase I did some research online (mainly this forum) and discovered that at some point a common problem with 121GW meters was the knob itself. Apparently there was a recall done at some point regarding the contact issues (knob replacement and addition of a shim). This took place months earlier. Common sense suggested that my meter should have already been free of this issue. This couldn't be farther from the truth.

After a month of very, very light use the meter is basically unusable. The knob wipers stopped making a good contact with the PCB (i think) and the meter reboots constantly while switching modes. Resistance mode cannot be turned on at all. The meter just turns off when I select it. The issue is present for every single knob position.
I made a short video where the issue is clearly visible:



As you can see, this is clearly not a 121GW revision with a fixed knob. I must have received an older, flawed version. This is absolutely unforgivable for a meter this expensive (and every other for that matter). What I find the most frustrating is that the recall was done some time before I bought my meter from the EEVBlog store. At that point I should expect this issue to be already resolved but in the end I recieved a meter with this exact defect still present.

I've sent Dave an email describing these issues on 5th October. He replied a week later and promised to send me a new meter. I was really happy about that. So why am I even writing this post, you may ask? Well, because the new meter has never been shipped and Dave has not replied to any of my emails since then :palm:. I've been trying many times to contact him through at least 3 EEVBlog email adresses and sending him PMs on the forum, asking why the new meter hasn't been shipped. Three weeks have passed and I have not recieved any reply. I have no idea why.

I can only hope that this post will grab Dave's attention and that my meter will get replaced eventually. Do you know if there is any other way to contact Dave or to fix the meter? I just want to be able to use the product i paid for.

Thank you for your help in advance,
A VERY frustrated customer.

Hello, not sure if this has been dealt with. Are you able to check whether a shim is installed internally in your meter.
It should be there. The shim resolved that issue earlier on, but it is possible your unit is missing this part...
 

Offline Antonov225

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Re: EEVblog 121GW Multimeter Issues
« Reply #761 on: December 05, 2018, 04:47:57 am »
Hi, This issue has been resolved. I have already received a replacement meter from Dave. Thank you.
 

Offline nonentity

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Re: EEVblog 121GW Multimeter Issues
« Reply #762 on: December 05, 2018, 09:46:40 am »
Quote
The resolution of the capacitance is 0.01 nF, unless I've misunderstood you might be using it for values out of the meters range.


My apologies, my message and post had the wrong capacitance value.  The capacitance used was 0.14 nano-farad.   Please see the corrected EEVblog 121GW Multimeter Issues Reply #869
« Last Edit: December 05, 2018, 03:59:10 pm by nonentity »
 

Offline DavidDLC

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Re: EEVblog 121GW Multimeter Issues
« Reply #763 on: December 06, 2018, 05:38:15 am »
I just installed firmware version 1.57, and it still shows a fixed current value of about 34 mA with nothing connected.

I had to go back to 1.26.

Does anybody know about this issue ?

David DLC
 

Offline chronos42

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Re: EEVblog 121GW Multimeter Issues
« Reply #764 on: December 06, 2018, 08:24:23 am »
I just installed firmware version 1.57, and it still shows a fixed current value of about 34 mA with nothing connected.

I had to go back to 1.26.

Does anybody know about this issue ?

David DLC

look at #819 in this thread, maybe that helps.
 
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Offline Seppy

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Re: EEVblog 121GW Multimeter Issues
« Reply #765 on: December 06, 2018, 11:28:13 am »
Quote
The resolution of the capacitance is 0.01 nF, unless I've misunderstood you might be using it for values out of the meters range.


My apologies, my message and post had the wrong capacitance value.  The capacitance used was 0.14 nano-farad.   Please see the corrected EEVblog 121GW Multimeter Issues Reply #869

Right, the app just hasn't been updated thats a planned update (needed because multimeter added some capacitance ranges).
After a while I have been able to reproduce the issue, we will look into this.
 

Offline joeqsmith

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Re: EEVblog 121GW Multimeter Issues
« Reply #766 on: December 16, 2018, 04:12:18 am »
Seems like YOU are the one polluting it.  Have anything technical to add?

I'll be very clear again.
This thread is for REPORTS of bugs and issues and CONFIRMATIONS of those bugs and issues.
DO NOT discuss them here, PLEASE!


I did not realize you were censoring posts in this area.   I resubmitted the post you removed twice because I literally thought I had forgotten to press the send key, not because I was trying to be a dick about it.   

I've had a go at cleaning up this area as well to save you the time.  Looks like about three pages were my posts so it does add up.   
« Last Edit: December 17, 2018, 04:44:07 am by joeqsmith »
How electrically robust is your meter?? http://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline chronos42

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Re: EEVblog 121GW Multimeter Issues
« Reply #767 on: December 16, 2018, 09:17:47 pm »
Hi,

I want point out the capatitance measure issue for low values again.
It was first discussed in the Firmware tread and also here.
This is a serious bug and makes the capacitance measurement unreliable for low values.
I still assume this is a firmware issue but I am unsure whether the developers are aware of this issue or not.

With a 100pF capacitor the meter has this behaviour:

First it shows the correct value.
After cycling through the modes it shows 21pF instead of 100pF and comes back very slowly to 100pF.

I had measured the waveform across the capacitor with a scope and found that it did not change in amplitude and time after cycling through the modes, so there seems no hardware related issue like wrong setups for the Hycon chip. Maybe a bug in the averange filter for the low capatitance mode? After cycling throug the modes it seems that the filter has a very long settling time for some reason. This issue should be investigated from UEI.
« Last Edit: December 16, 2018, 10:28:43 pm by chronos42 »
 

Offline chronos42

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Re: EEVblog 121GW Multimeter Issues
« Reply #768 on: December 16, 2018, 10:11:32 pm »
Hi,

beside of the unacceptable slow autorange in ohms mode there is another issue in this mode.

After shorting the leads and pushing the rel button the meter zeros out the low ohm range and compensates the lead resistor as expected. But it also disables simultaneous the autorange function.
Why? That makes no sense, no other of my meters does this.
Re-enabling the auto mode deletes the resistor compensation  :palm:.
That should be changed.
 

Online IanB

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Re: EEVblog 121GW Multimeter Issues
« Reply #769 on: December 17, 2018, 03:32:09 am »
After shorting the leads and pushing the rel button the meter zeros out the low ohm range and compensates the lead resistor as expected. But it also disables simultaneous the autorange function.
Why? That makes no sense, no other of my meters does this.
Re-enabling the auto mode deletes the resistor compensation  :palm:.

As far as I know this is typical behaviour in DMMs. The Rel function is specific to the range you are in. If a meter autoranges to a different range the Rel function is cancelled.

It appears the 121GW is locking in the Rel'd range rather than autoranging away and undoing the Rel setting. This seems to me like a reasonable and valid design choice.
« Last Edit: December 17, 2018, 03:34:07 am by IanB »
I'm not an EE--what am I doing here?
 

Offline GeoffreyF

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Re: EEVblog 121GW Multimeter Issues
« Reply #770 on: December 17, 2018, 04:00:35 am »
When people characterize something as "unacceptable" - in this case auto range, why not state what you are comparing it too and how you have used that other "acceptable" device.  Price, other functions? All really acceptable?  Why didn't you buy that one?
US Amateur Extra W1GCF.
 

Offline CDaniel

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Re: EEVblog 121GW Multimeter Issues
« Reply #771 on: December 17, 2018, 04:23:37 am »
GeoffreyF , 121GW is very slow in comparison with cheap or expensive multimeters , so stop being a fanboy troll . This firmware program should be scrapped completely and start from scratch with speed efficiency in mind . With a PIC family microcontroller a long time ago many , many users could have done a better firmware .

To add something , autorange hysteresis is 55000 counts up and 40000 counts down .Unreasonable huge . So , when you measure a 470ohm resistor from infinite resistance ( autoranging down ) , it will autorange in the 5K range and you will see 0,4700K .

But if you short the leads first and wait for 0 ohm reading ,  then measure fast ( now autorange is going up in ranges )  that 470ohm resistor , it will autorange correctly in 500ohm range as 470.00ohm .

« Last Edit: December 17, 2018, 04:38:08 am by CDaniel »
 
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Offline Marco1971

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Re: EEVblog 121GW Multimeter Issues
« Reply #772 on: December 17, 2018, 04:43:52 am »
Hi,

beside of the unacceptable slow autorange in ohms mode there is another issue in this mode.

After shorting the leads and pushing the rel button the meter zeros out the low ohm range and compensates the lead resistor as expected. But it also disables simultaneous the autorange function.
Why? That makes no sense, no other of my meters does this.
Re-enabling the auto mode deletes the resistor compensation  :palm:.
That should be changed.

Hi, my Fluke 89IV/189 and 287 (with firmware 1.16) all do it in the same way with automatically switching to MANUAL ranging.

Regards from Italy.

Marco1971
 

Offline GeoffreyF

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Re: EEVblog 121GW Multimeter Issues
« Reply #773 on: December 17, 2018, 05:14:35 am »
GeoffreyF , 121GW is very slow in comparison with cheap or expensive multimeters , so stop being a fanboy troll . This firmware program should be scrapped completely and start from scratch with speed efficiency in mind . With a PIC family microcontroller a long time ago many , many users could have done a better firmware .

So you can't make any real point and you call me a fan boy troll?  You discredited yourself completely.   Did I say I was a "fan"?  No.  I own one. I own others.   Troll?  I am not one of these people who never gets tired of repeating the same point again and again, completely unproductively.   As for "Scrapped completely" (as opposed to correcting bugs).  It is equally obvious you never really worked on production code. 

This is an Engineering blog - that means numbers, facts, comparisons - not rude school boy remarks. 
US Amateur Extra W1GCF.
 

Offline HKJ

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Re: EEVblog 121GW Multimeter Issues
« Reply #774 on: December 17, 2018, 05:28:07 am »
A few meters do not disable auto range when doing min/max or REL, one of them is Hioki DT4282
 
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