EEVBlog 121GW Discussion thread

[1anX]

Just tested it. AUTO DC+AC mode and I supplied about 25Vdc and it hunts. Raised voltage to about 44Vdc and it reads correctly. Lowering the DC voltage and it hunts again.

It looks like all pre-production errors are still present in the first batch of production meters of the 121GW. Even my crappy UNI-T UT71E is doing a better job in all of the discussed bugs.

I like to hear something soon from Dave how they will go on with the production meters of the early adopters... 

A fair and candid, (pun intended) comment !

I cant see us hearing from Dave anytime soon as he is keeping a very low profile and with good reason. He cant comment until he has a defined course of action to rectify the bugs and switch issue. Its up to UEi at this stage to pull their finger out and and turn this first "production" run meter into what it should be.

Dave needs to be extremely diplomatic with both his backers/buyers and with UEi. Nothing to be gained by pounding a fist on a table! As much as I dislike the situation with this meter, I am following Dave's lead with patience and high expectations for speedy fix.

The meter's potential with its unique specification is high and so is its potential for high worldwide sales. It will be interesting to see if Dave can turn the V1.0 bugs around and turn it into a best seller. It will also be interesting to see if UEi has the technology and ability to respond quickly to this meter's faults and apply thorough testing before releasing V1.01.

The EEVBlog forum has proved its worth once again by providing insights into this meter's teething problems and also presenting some impressive solutions. The firmware hacking and Joe's testing of the prototype, and informing us all of the carryover bugs, stand out for me!

[tpw_rules]

Are you both using the same firmware? 

The pre-production meter would lock in depending on the AC and DC components.  If you have a cheap power supply with a lot of ripple for example, the meter may actually read correctly.   

V1.02 original (no autoranging patch)

Strange.  You would think it would do it or it wouldn't.  I am not sure what sort of regression testing is being ran on the patched code.  Maybe the patch has something to do with it.   

Yeah, it was a regression.

The original problem was that AC/DC mode operates by switching the meter mode every measurement and caching the result, to mix in when measuring the other mode. So you'd get:
1. read 5.5000V DC, store as 55000 counts. Autorange decides to range up.
2. switch to reading AC, read 00.000V, add previous DC counts to show 55.000V. Autorange decides to range up.
3. switch to reading DC, read 005.50V, add previous AC counts to show 005.50V. Autorange decides to range down.
4. switch to reading AC, read 00.000V, add previous DC counts to show 00.550V. Autorange decides to range down.
5. and so on and so on, literally forever.

The obvious way to bring the meter back is to input a DC value that's > 4000 and < 55000 counts, which explains in Joe's video why it hunts starting around 5.0000V and comes back at nearly exactly 40.00V. Or, input an AC value that results in a value within that range after both a bogus addition and a correct addition (by the way, it's not addition, it's sqrt(AC^2+DC^2) which I don't entirely understand why), so autorange settles down. So yeah, it definitely can depend on the AC and DC content.

Anyway, they fixed this by adding a delay so it would show two measurements before autorange decided to act again, thus flushing the bogus cached counts. But my patch mashes that delay to 0 whenever autorange acts (vs. the user), giving the same situation. My apologies for the confusion, but I can't test anything due to the delay in the US meters. I'll look into either applying that only to the resistance range, or perhaps just not to AC+DC mode.

[EEVblog]

Isn't one of the selling points is that it can be turned with one hand?

So far no one has said that if there was no wobble, if it could or not be used with one hand.

If so, probably only after Dave realised early on that is was never going to be as stiff as the BM235 (which was a selling point about how stiff it was, and any shootout would get extra point for stiffness), and quickly turned a negative into a positive.  I think we underestimate how good he is at the marketing, and his own down playing of this skill, is a key part.  I would bet, if he could have got them to make it as stiff, he would have.

Actually, I think the BM235 range switch is a bit too stiff, I find i have to apply some downward pressure in order to switch it one handed on a smooth surface, worse if it's up on the tilt stand
Whilst the 121GW technically has the same pressure issue, the action is less "violent" than the BM235 and requires less force. Sometimes I think that's better, sometimes not, depending upon my mood and usage scenario, it's entirely personal preference. The 121GW range switch was simply UEi's standard method used in their other meters and I didn't see any reason to mess with it.

[nuclearcat]

A bit fun with 121GW bluetooth data stream + USB microscope + (C++/wxwidgets/OpenCV to add OSD layer)
https://www.youtube.com/watch?v=nIbdnlQJ1fA&feature=youtu.be
Still PoC, not sure if such will be useful, or maybe such apps already exist.

[Seppy]

I am having problems with connecting the 121GW app from dave2. I did no get any data shown in the app up to now. Most time it even does not connect.

I first run bluetooth and connect to the 121GW then I start the app. Sometimes when I click on refresh I can see the 121GW. Only one time it was able to connect (but no data shown, only white screen). Most time it says "connecting..." but never does.

The other app "EEVBlog 121GW" sometimes connects successfully and shows some values but sorry, it's so ugly.

/EDIT:
Now I got it running for one time but I think I am missing some data on the screen?

There are a couple things to note when using the app and its easy to prevent it from working.
1. Make sure only one instance is running at a time.
2. You shouldn't need to pair the app at all on android to give that a try before you go and pair the device.

It seems people tend to open the app to see what they installed then pair or enable bluetooth, then open a second instance of the app. That is known to cause issues.

[ChrisG]

Hi Joe, I just tried it and can not replay your issue in the video. 10Vpp sine-wave from the Siglent SDG 2042X into the 121GW and the BM869s connected too. This 121GW on any ms range indicates correctly at frequencies from 10Hz to 200Hz (10, 50, 100, 200). I can not get a wrong reading on the meter. Still on V1.02 not patched for slow update rate.

[ChrisG]

Well it was not a cheap power supply at 500€ but will try with a 9V battery then later. I’ve so far not se3n what you show in your viceo. Anyone else?

Hi Joe, tried a 9v (actually bit dated and went to 8v) battery. Apart from slow auto-ranging no issue on locking in. So if slow auto-ranging is hunting then yes but I assume not.

[benst]

Just want to add that rotary switch wobble issue exists also with my meter (EU shipped). https://youtu.be/pjaWWMoPMsE
Is this same for everyone or only part of the already shipped meters?

Mine (#000499) is similar, maybe a bit less.

Edit: and I have the funky display sometimes. Wiggling the switch a few times fixes it.

Ben

[dcac]

Yet another auto ranging benchmark - Keysight U1461A which also uses hy3131 but has a 6600 counts mode - goes from infidelity infinity to zero ohms in just 2.2-2.4 sec. Though it only goes down to 0.1 ohms resolution so to be fair 121gw has two more range steps to complete. Still seems promising if a low resolution mode can be added to 121gw.

Perhaps sniffing the bus on how U1461A controls the hy3131 could give an idea how it achieves this speed. But if we're unlucky there are other HW differences that makes the 121gw so dreadfully slow.

[ANTALIFE]

Quick question/problem, I am trying to measure power (VA) of a device plugged into an AUS AC socket.
I have everything connected as per diagram on pg46 of manual (11 December 2017 rev), when I switch to mVA/VA mode (in AC too) I get Vac too large to read.
Interestingly enough I can measure Vac & Iac individually which come out as ~245Vrms & ~16mA (rms?)

So my question is, am I doing something wrong or is the meter not designed to measure stuff plugged into an AC socket

[ChrisG]

Hi Joe, I just tried it and can not replay your issue in the video. 10Vpp sine-wave from the Siglent SDG 2042X into the 121GW and the BM869s connected too. This 121GW on any ms range indicates correctly at frequencies from 10Hz to 200Hz (10, 50, 100, 200). I can not get a wrong reading on the meter. Still on V1.02 not patched for slow update rate.

Well it was not a cheap power supply at 500€ but will try with a 9V battery then later. I’ve so far not se3n what you show in your viceo. Anyone else?

Hi Joe, tried a 9v (actually bit dated and went to 8v) battery. Apart from slow auto-ranging no issue on locking in. So if slow auto-ranging is hunting then yes but I assume not.

9V I assume was for the AC+DC mode.  If you read the previous posts, looks like the reason for the difference was indeed the patch.   It appears they did address a few of the problems.   I think the big one is what appears to be a metallic dust in those previous pictures.  If you have been putting a few cycles on yours (even a few hundred total) and a camera that you can take some close ups of the pad area, it would be interesting to see a few more pictures.   

Hi Joe, I'll give that a go the coming days. Too much normal work going on for me at the moment. I'm not sure I'm looking forward to this to be honest. If the tracks are or seem to deteriorate quickly I would be appalled. Are you getting an official, non pre-production, 121GW soon perhaps?

[ChrisG]

Hi Joe, I just tried it and can not replay your issue in the video. 10Vpp sine-wave from the Siglent SDG 2042X into the 121GW and the BM869s connected too. This 121GW on any ms range indicates correctly at frequencies from 10Hz to 200Hz (10, 50, 100, 200). I can not get a wrong reading on the meter. Still on V1.02 not patched for slow update rate.

Well it was not a cheap power supply at 500€ but will try with a 9V battery then later. I’ve so far not se3n what you show in your viceo. Anyone else?

Hi Joe, tried a 9v (actually bit dated and went to 8v) battery. Apart from slow auto-ranging no issue on locking in. So if slow auto-ranging is hunting then yes but I assume not.

9V I assume was for the AC+DC mode.  If you read the previous posts, looks like the reason for the difference was indeed the patch.   It appears they did address a few of the problems.   I think the big one is what appears to be a metallic dust in those previous pictures.  If you have been putting a few cycles on yours (even a few hundred total) and a camera that you can take some close ups of the pad area, it would be interesting to see a few more pictures.   

Hi Joe, I'll give that a go the coming days. Too much normal work going on for me at the moment. I'm not sure I'm looking forward to this to be honest. If the tracks are or seem to deteriorate quickly I would be appalled. Are you getting an official, non pre-production, 121GW soon perhaps?

Personally, I would rather know if there was a problem early on.   If there is, maybe it could be corrected before any major damage happens to the PCB.  What sort of warranty did you get?   If you put a few thousand cycles on the switch over the next few weeks and the parts are damaged, is the meter covered? 

From what I understand, very few meters made it to people in the USA so even if I had joined, I doubt I would have it.  Strange as I would have thought they would have been the largest consumer.   Anyway, I was concerned that there had not been a full review of the meter that disclosed what the problems were and how they would be mitigated.  Obviously, there were problems that have been known for some time.  I had asked a question in the kickstarter that went unanswered.   Also, looking at the closeup video, it appeared the meter's weak front end was still in play.  Again, it's not a lot of money but if I bought one it would be to run it to failure and I did not want to invest this amount of time if the design was still not stable or if it was not going to be an improvement over the earlier version.  If and when it looks like the meter is stable and it becomes available through normal channels, I may run one.   For now, it seems it is way too early.   

Agree with you Joe and at the same time I'm happy I did join the campaign very much so. It's a joint effort in the end of this community to come up with a solid product and I would not have expected it to be perfect during the first production version. However traces on the PCB which are not up to spec would a, as said already, disappoint me.
BTW: I thought the front end was pretty okay and not weak. Did I miss it in your pre-production test video?

[Smokey]

....Keysight U1461A .... goes from infidelity to zero ohms in just 2.2-2.4 sec

HA!  I thought infidelity was already due to low resistance

[dcac]

....Keysight U1461A .... goes from infidelity to zero ohms in just 2.2-2.4 sec

HA!  I thought infidelity was already due to low resistance

lol, yeah autocomplete at its best - should of course have been - infinity to zero ohms in 2.2-2.4 sec.

[dcac]

From what I understand, very few meters made it to people in the USA so even if I had joined, I doubt I would have it.  Strange as I would have thought they would have been the largest consumer.

Probably the large time difference between USA and Australia caused potential consumers to be too late in the game - at least for the first batch anyway.

[nidlaX]

From what I understand, very few meters made it to people in the USA so even if I had joined, I doubt I would have it.  Strange as I would have thought they would have been the largest consumer.

Probably the large time difference between USA and Australia caused potential consumers to be too late in the game - at least for the first batch anyway.

No... The US meters were simply stuck in customs all the way up to when the switch tolerance issue was reported. Now they won't ship until that issue is fixed.

[EEVblog]

Look at the data.  There are several meters that have done very well in these tests.  2KV is lower than the average and not something I would be impressed with.  I was just as surprised by the Fluke 87V result.  Received a lot of negative posts over that one from the fans.  Not much I can say about how the meter's do in the tests.   I can say that the Fluke 87V is not what I consider the goal post.

I guess this goes to show how important this stuff actually is in the real world, as much as we all like to fuss over these sorts of details because, you know, we are nerds.
I have never heard a single person complain that the Fluke 87 series isn't a robust industrial meter, and not surprising because it's been an industry standard for like 30 years now.

[EEVblog]

Perhaps sniffing the bus on how U1461A controls the hy3131 could give an idea how it achieves this speed. But if we're unlucky there are other HW differences that makes the 121gw so dreadfully slow.

FYI, the 121GW is now on par with the U1282A.

[1anX]

Perhaps sniffing the bus on how U1461A controls the hy3131 could give an idea how it achieves this speed. But if we're unlucky there are other HW differences that makes the 121gw so dreadfully slow.

FYI, the 121GW is now on par with the U1282A.

So whats that in Seconds?
How are UEi progressing on the bug fixes?
Any timeline on when they expect to have a fully functional and thoroughly tested meter to ship?
Sounds like progress is being made, so thats good news 

[exe]

Dave, a week or two ago you mentioned Dave2 was working on making some instructions how to make own firmware for the meter (or was it only about how to flash it?). Is there any progress on this? I understand you are busy guys, but I'd appreciate any information on how to roll own firmware so I could start developing it (or other duded smarted than me). I know it's possible to reverse-engineer the current firmware, but I think it's a waste of time this is inefficient. Also, I think it is already proven community can fix problems much faster than any manufacturer.

I also would like to get more updates on the meter. Any rumors, estimations, etc. So, we could see it's not abandoned. If possible. Or, better, a UEI representative here in the thread. Like other manufacturers do on this forum (e.g., MicSig, R&S, Siglent (tautech), Rigol, etc).

[joeqsmith]

Look at the data.  There are several meters that have done very well in these tests.  2KV is lower than the average and not something I would be impressed with.  I was just as surprised by the Fluke 87V result.  Received a lot of negative posts over that one from the fans.  Not much I can say about how the meter's do in the tests.   I can say that the Fluke 87V is not what I consider the goal post.

I guess this goes to show how important this stuff actually is in the real world, as much as we all like to fuss over these sorts of details because, you know, we are nerds.
I have never heard a single person complain that the Fluke 87 series isn't a robust industrial meter, and not surprising because it's been an industry standard for like 30 years now.

As I have mentioned before, I  really don't know what the failure rate is for the 87V.  I've seen posts where they have failed which is not too surprising.  Enough hype and marketing can easily cover up any short comings.   You are right that there are people that that care less about the marketing and more about the results.  I certainly classify myself in that category and offer these test results as proof of that. 

Another data point we have is the age of the 87V and how it compares with Fluke's newer designs.  I've also looked at the 101,107,115 and 17B+.  All newer, all from China.   The worst of them was the Fluke 17B+ that was damaged at 10KV 50us.   Sure, it could be by accident that their newer meters are so much more robust but I doubt it.  I suspect it has more to do with reducing the number of field failures and warranty returns.  But again, I really don't know and can only present the data.   It's up to the people that view it to interpret it.     

[EEVblog]

Look at the data.  There are several meters that have done very well in these tests.  2KV is lower than the average and not something I would be impressed with.  I was just as surprised by the Fluke 87V result.  Received a lot of negative posts over that one from the fans.  Not much I can say about how the meter's do in the tests.   I can say that the Fluke 87V is not what I consider the goal post.

I guess this goes to show how important this stuff actually is in the real world, as much as we all like to fuss over these sorts of details because, you know, we are nerds.
I have never heard a single person complain that the Fluke 87 series isn't a robust industrial meter, and not surprising because it's been an industry standard for like 30 years now.

As I have mentioned before, I  really don't know what the failure rate is for the 87V.  I've seen posts where they have failed which is not too surprising.  Enough hype and marketing can easily cover up any short comings.

Or maybe the "short comings" aren't really short comings in a practical world? And the 87V's reputation as one of the most reliable and robust meters on the market is actually well earned?
Maybe the 61010 CAT IV 600V rating as tested by UL is more than enough for almost everyone?
For instance, the now infamous 87V GSM bug wasn't found for a decade, and countless units sold of the biggest selling meter on the market.
Or the very popular Keysight U1272A's EMC problem taking how long before someone found it?

[dcac]

Perhaps sniffing the bus on how U1461A controls the hy3131 could give an idea how it achieves this speed. But if we're unlucky there are other HW differences that makes the 121gw so dreadfully slow.

FYI, the 121GW is now on par with the U1282A.

FYI, that still makes it dreadfully slow - I’m sorry, but I guess I miss the old clonk-clonk-clonk Dave who’d facepalme and hammer his failbutton through the desk if confronted with an auto-ranging this slow on a DMM in this class. But still I really do appreciate what you’re trying to provide with the 121gw and my main point was that the U1461 was so much faster in a 6000 count mode.

Am I expecting UEi to provide a fast 5000 count mode for 121gw? - no not really - but they’re in a much better position having the FW source code to make an addition like that - compared to hacking/patching the binaries. But I’m starting to wonder if UEi them self is limited in what they can achieve with the development tools they’re using. Else I can’t really understand why 121gw ever was released with an auto-raging that was so slow that backers would go seriously WTF!

[ChrisG]

Perhaps sniffing the bus on how U1461A controls the hy3131 could give an idea how it achieves this speed. But if we're unlucky there are other HW differences that makes the 121gw so dreadfully slow.

FYI, the 121GW is now on par with the U1282A.

FYI, that still makes it dreadfully slow - I’m sorry, but I guess I miss the old clonk-clonk-clonk Dave who’d facepalme and hammer his failbutton through the desk if confronted with an auto-ranging this slow on a DMM in this class. But still I really do appreciate what you’re trying to provide with the 121gw and my main point was that the U1461 was so much faster in a 6000 count mode.

Am I expecting UEi to provide a fast 5000 count mode for 121gw? - no not really - but they’re in a much better position having the FW source code to make an addition like that - compared to hacking/patching the binaries. But I’m starting to wonder if UEi them self is limited in what they can achieve with the development tools they’re using. Else I can’t really understand why 121gw ever was released with an auto-raging that was so slow that backers would go seriously WTF!

That would not be good at all and with all the issues piling up till now and the fact that some if not most are really HW related it starts to be a real problem for me. This morning I had to cycle the knob 3-4 times before it wanted to switch on?     how can that be?

[ChrisG]

POSTING again since the other one got lost?

Herewith the pictures of the PCB selector tracks.