EEVblog 121GW Multimeter Issues

[beanflying]

It’s too bad Fanboys and Trolls are such a major issue with the 121gw as their posting seems to drown the real hardware and firmware problems being reported.

Fanboy I am not but it is in my on site bag and when I switch it on it is accurate and does what I need. This thread has been derailed to the point where is useless as any sort of bug tracker.

And yep the firmware does need some work but bitching and moaning isn't going to speed it up!

[chronos42]

Well, bug tracking only works with a list that summarizes all recognized bugs, all fixes with an exact description and all open issues. That was often desired, but never done.  It does not work in the current state (forum with a lot of "noise"). Several described bugs are simply ignored (like the very strange "low capacity bug", the 500V range loop etc.). I can't understand why this is not done more professionell.

[dcac]

Well, bug tracking only works with a list that summarizes all recognized bugs, all fixes with an exact description and all open issues. That was often desired, but never done.  It does not work in the current state (forum with a lot of "noise"). Several described bugs are simply ignored (like the very strange "low capacity bug", the 500V range loop etc.). I can't understand why this is not done more professionell.

I think the weird ‘low capacity bug’ is caused by drift in some of the input protection components causing a negative capacitance offset, but in the 121gw cap measurement any value below zero gets set to zero and then when the offset the meter was calibrated at gets subtracted you can get significant errors.

I also think UEI already battled with this problem as they are not doing the cap measurement like it is described in the hy3131 datasheet, they are using constant current instead of constant voltage for this range, this causes the measurement to be slower but I guess they figured the drift had less influence this way.

Anyway, a simple solution would be to allow negative readings in the cap mode, that value can then be compensated for with the rel button and you could get a correct reading at least for that moment at that particular state of drift.

[e0ne199]

hello anyone, any info about new firmware? (>v2.0)

[Nerull]

The fact is it doesn't have an easy way to see/download the data logging . This is a fair criticism . You should have pointed out clearly this deficiency at the "supporters area" early discusions 

Do you really go out of your way to be an ASSHAT?

Data being logged to an internal card at speed that is the same as on the display is not an 'issue' and you once again are being a TROLL !

I"m a troll for fanboys like you , the logging has issues not just the physical acces , a pain in the butt because they couldn"t do it wirelessly or add a normal computer interface . Whatever ...

As you have spent maybe half of your posts TOTAL on this forum whining bitching and moaning about this meter, the manufacturer and the distributor you are an ASSHAT ! Stop being a serial SOOK

Maybe, and I know this sort of thinking is discouraged here, but just maybe someone paid a fair amount of money for a product and isn't satisfied with what they got.

Just imagine seeing people being screamed at for being insufficiently brand loyal for documenting issues in a Rigol thread.

You bought a meter. It's a tool. It's really okay if other people don't like it. You'll be okay, really. You don't have to get so worked up.

[beanflying]

This is not about brand loyalty at all!

Mr CDaniel's MAJORITY of posts on this forum have been generally negative in sentiment about this ONE product, the manufacturer and Dave personally and perceived lack of action to his demands. Why his butt is not in a sling for this is because Dave is who he is and has let him be a trolling whiner. His first 25 posts were just about this meter as an example!

Repeatedly hammering the same point again and again is not what this thread is for. What Dave & UEI distill from the content is made harder by the noise.

Factual and technically fair critique is always fine and if you go back to page one of this thread there is some initial thoughts of mine that were not positive and still remain valid to some degree with the later firmware upgrades.

[CDaniel]

To be clear , I criticised the product and the company / persons unwilling or incapable of resolving the firmware issues for 2 years now .
Unfortunatly is David's multimeter and fanboys will jump in  I'm sure he doesn't mind and want to improve it , as himself strongly criticize other's people design faults .
The fact is there are many small and some big issues , not normal for any reputable brand . After all is just a multimeter .
This is not a thread for praising how good it is , so if for your level is OK then don't read and be happy .

[vk3zgw]

Bluetooth issue.

Sorry if this has been raised but after searching the forum for sometime, I haven't found an answer.

Phone, ZTE Android 7. Checked update status, "up to date".
Switched on BT on phone.
Activated BT on meter.
Opened App. No BT address. Refreshed many times, no go. Tapped Settings in the app, nothing happens and no BLE page either. Uninstalled the app and reinstalled. No change.

I can pair the meter so it's transmitting, but I read David's post saying it doesn't use pairing as its BLE. So removed it from the list on the phone, still nothing. Tried it when paired but same result.

Meter is 2.0

Any clues?

Thanks Geoff

[CDaniel]

For the first time you use the app , first you have to pair the devices from the phone bluetooth menu , then open the app and it will show you the meter .
If you opened the app before pairing it will not show the meter , only after you close the app ( it doesn't have close button so you must use the phone to shut it down ) and then start it again .
After that it will pair automatically and the meter address will pop up in the app even if was opened before .
I checked now and is working , I have v2.0

[vk3zgw]

Thanks CDaniel,

It turns out that I require to have Location Services on for the app to have it work. I could see the meter in the BT list and it was already paired, just needed the Location for some reason

Cheers
Geoff

[Kilrah]

In Android access to BT LE devices is tied to Location services.

[EEVblog]

It turns out that I require to have Location Services on for the app to have it work. I could see the meter in the BT list and it was already paired, just needed the Location for some reason

Unfortunately the location requirement is something that the BLE stack drivers require, so it's not our app that needed that or is doing something nefarious with it. Some people have had exception to this on principle/privacy concerns and I can completely understand that. Of course the app is full open source so it's possible to check that it's not doing anything with the location access.

[EEVblog]

FYI, David will be adding v2.01 to the website shortly because some people have asked, and Welectron have new stock with 2.01. Nothing to get excited about, it's just an internal bug fix related to factory calibration. So no need to upgrade for existing meters, it will not do anything for you, unless you plan on completely factory recalibrating your meter for some reason.

[hwj-d]

Yes. I have it from 12.08.2019 Welectron new charge with V2.01, wondering it wasn't published at this time. 

[CDaniel]

Probably because it doesn't solve anything , like David said .

[burra7]

Location Service = Turn on GPS then it works sometimes, seems like the 121gw app on Android is not that stable. Connect, dissconnect ...need to be improved. Tested with Nokia6.0 running Android 9 patch level 1 August 2019

[Halcyon]

Not so much of an issue, but I guess a suggestion...

When performing a firmware update, the LCD looks like it's displaying "Douun". I fully understand that the two U's together are supposed to resemble a W. However, would it be possible to make it display "LOAd" or "Run.." instead? OCD kicking in

[Dr. Frank]

FW 2.02 solves the 550..600 V_dc unsteady ranging problem, introduced with FW 2.00.

Instead, the 1000 V_dc range does not down-range any more  @ Uin < 500 V, but stays in this 1000 V range until U < 60.0 V, i.e. @ 59.9 V.

All other ranges, 500V, 50V, 5V down-range and up-range correctly.

Frank

PS: Gee, wouldn't it be possible for UEI, to test firmware changes, especially such specific bug corrections, more thoroughly?

[CDaniel]

Small cap drift or whatever you want to call it is not resolved ...
Resistor measurement seems faster ( maybe my impresion ) , but very prone to pick up the mains noise as before .

[EEVblog]

When performing a firmware update, the LCD looks like it's displaying "Douun". I fully understand that the two U's together are supposed to resemble a W. However, would it be possible to make it display "LOAd" or "Run.." instead?

Nope, that would require a change to the bootloader.

[e0ne199]

if this multimeter's firmware is truly open source, i believe it will sell like hot cakes...

[beanflying]

if this multimeter's firmware is truly open source, i believe it will sell like hot cakes...

It was never open source or intended to be. The Bluetooth is a different matter.

[EEVblog]

if this multimeter's firmware is truly open source, i believe it will sell like hot cakes...

It was never open source or intended to be. The Bluetooth is a different matter.

That was the original hope, but UEi have said they will not allow this as it contains proprietary code used on others products etc.

[IanB]

if this multimeter's firmware is truly open source, i believe it will sell like hot cakes...

It was never open source or intended to be. The Bluetooth is a different matter.

That was the original hope, but UEi have said they will not allow this as it contains proprietary code used on others products etc.

I wonder, would it be possible to have the internal hardware interfaces documented so that a completely independent firmware might be written? I would be a "community edition" of the firmware, totally unconnected to the UEi version.

I don't underestimate how complex that task might be, but if the emerging source code were shared on GitHub for example, then various people could contribute to it and it could be built up over time. It might be a fun project and it doesn't have to be completed overnight.

[EEVblog]

if this multimeter's firmware is truly open source, i believe it will sell like hot cakes...

It was never open source or intended to be. The Bluetooth is a different matter.

That was the original hope, but UEi have said they will not allow this as it contains proprietary code used on others products etc.

I wonder, would it be possible to have the internal hardware interfaces documented so that a completely independent firmware might be written?

It's not just the hardware, it's the firmware bootloader + all the intricacies of how the calibration data is handled. Sure you could write your own firmware from scratch but then you'd have to recalibrate the meter, a job which most people do not have the equipment for + you need the programmer if you want to change the bootloader.
This has been discussed before. Given that UEi don't wan to release that stuff, it's just not worth the effort for the few people that would have the capability to do this. Maybe someone could reverse how the calibration is done etc, and figure out the bootloader, but it's tough ask.