EEVBlog 121GW Discussion thread

[CDaniel]

Anybody familiar with the schematic will see from the picture that the replacement 2 transistor board is for output protection in resistace/capacitance mode ... D7-D8 1N4007 . Output = the current source or charge / discharge circuit used for measuring resistors or caps .

[1anX]

How long before the next gen 121GW becomes available with the new PCB and updates?

Well past this batch of 700, they have a lot of blank boards yet. Can't give a timeline.

I'm quite happy to hardware mod my current 121GW and would love to see a video on EEVBlog on the modding and re-calibrating this meter.

Most people do not have the capability to calibrate the meter, it requires precise generated values from a proper meter calibrator.

Its a pity that UEI and EEVBlog didn't bite the bullet and scrap the 700 out of spec PCBs that require shims for the switch to work properly. The hardware upgrades could have been incorporated on the new PCB giving the meter the stability and speed it requires to lift itself from being just another kickstarter prototype.

I needed another similar spec meter and would have waited for the upgraded 121GW to appear if it featured the necessary upgraded hardware. As you could not provide a time frame or even list the fixes that would appear in the next production model I have purchased another meter.

I purchased the similar priced Brymen BM867s, ($300) as I know what the performance and accuracy are and how reliable this meter has shown to be under many different tests. This is a professional and proven design that features fast update rates and stable display readings. IMO this older Brymen meter's performance is what the 121GW needs to match and better if it is to stand the test of time and continue to sell.

[CDaniel]

The big issues are firmware related , the shim is working fine for the majority ( I don't want to say that they shouldn't do it right ). And that little shield for buttons + modified protection in resistance mode won't change much .

[ChrisG]

The big issues are firmware related , the shim is working fine for the majority ( I don't want to say that they shouldn't do it right ). And that little shield for buttons + modified protection in resistance mode won't change much .

Funny.  I don't see the firmware being big issues.  Certainly there are more firmware problems reported than hardware and they may be more visible to the average joe but I see getting a stable hardware platform as being a larger problem.   

Seeing them change from the single dimple contact to double and now back to single.  Looking at photos of the wear, I'm not convinced the meter will hold up.  Dave did run a life test on some version of it but it seems odd they are changing the design if all is well.     The same is true for the transient protection.  If Dave is going to make a statement that the meter passed cert and that's the end of the story,  then there should be no reason to change the front end.   It's good to hear they continue to develop the hardware.  I'm looking forward to seeing what they come up with.

I still believe both need to be taken care off but the biggest concern I now start to have is transparency on why the changes are happening single to double and back etc. For me there was never a good  response on why my meter had so much crud on the contacts after less then 100 power cycles. It took also quite some time to acknowledge the mechanical issue with the selector knob. All and all I am personally okay to support such an initiative, spend the money accept the risk of a possible lemon or brick but then I see room for improvement on the development process going forward. I do want to acknowledge here too that we can on this forum give plenty of updates, issue reporting or even rant on whatever we think should have been done and that in itself is worth something already.

[ChrisG]

How long before the next gen 121GW becomes available with the new PCB and updates?

Well past this batch of 700, they have a lot of blank boards yet. Can't give a timeline.

I'm quite happy to hardware mod my current 121GW and would love to see a video on EEVBlog on the modding and re-calibrating this meter.

Most people do not have the capability to calibrate the meter, it requires precise generated values from a proper meter calibrator.

Its a pity that UEI and EEVBlog didn't bite the bullet and scrap the 700 out of spec PCBs that require shims for the switch to work properly. The hardware upgrades could have been incorporated on the new PCB giving the meter the stability and speed it requires to lift itself from being just another kickstarter prototype.

I needed another similar spec meter and would have waited for the upgraded 121GW to appear if it featured the necessary upgraded hardware. As you could not provide a time frame or even list the fixes that would appear in the next production model I have purchased another meter.

I purchased the similar priced Brymen BM867s, ($300) as I know what the performance and accuracy are and how reliable this meter has shown to be under many different tests. This is a professional and proven design that features fast update rates and stable display readings. IMO this older Brymen meter's performance is what the 121GW needs to match and better if it is to stand the test of time and continue to sell.

Could not agree more with that. Though we were all very anxious to get our hands on the item. I remember I was really looking forward to it.  I have a BM869s and BM235 too and when I open these up I see no wear, no crud no nothing after years of usage.

[CDaniel]

The big issues are firmware related , the shim is working fine for the majority ( I don't want to say that they shouldn't do it right ). And that little shield for buttons + modified protection in resistance mode won't change much .

Funny.  I don't see the firmware being big issues.  Certainly there are more firmware problems reported than hardware and they may be more visible to the average joe but I see getting a stable hardware platform as being a larger problem.   

Seeing them change from the single dimple contact to double and now back to single.  Looking at photos of the wear, I'm not convinced the meter will hold up.  Dave did run a life test on some version of it but it seems odd they are changing the design if all is well.     The same is true for the transient protection.  If Dave is going to make a statement that the meter passed cert and that's the end of the story,  then there should be no reason to change the front end.   It's good to hear they continue to develop the hardware.  I'm looking forward to seeing what they come up with.

Ok , you are very interested in testing the switch , and surviving XXX KV transients , that's your job or hobby ( or both ) , and it's fine , but what hardware issues that we know are important for an average customer that will buy this meter ?

The shim is working fine , the 2 diodes 1N4007 are leaky and temperature dependent but affect mostly 50Mohm range .
I made a shield for membrane buttons as in David's picture , so far it is still sensitive to touching that zone , I will test more .

Firmware bugs are numerous , from slow autorange , missing features , etc , maybe someone should compile a list .
To make a good and efficient firmware , not just working , needs money ( a team , not one or two people working in spare time  ) , skill and will .

[Terry01]

I got side tracked yesterday so didn't get to test the "hysteresis" but I will do it today for sure and post the results.

[joeqsmith]

The big issues are firmware related , the shim is working fine for the majority ( I don't want to say that they shouldn't do it right ). And that little shield for buttons + modified protection in resistance mode won't change much .

Funny.  I don't see the firmware being big issues.  Certainly there are more firmware problems reported than hardware and they may be more visible to the average joe but I see getting a stable hardware platform as being a larger problem.   

Seeing them change from the single dimple contact to double and now back to single.  Looking at photos of the wear, I'm not convinced the meter will hold up.  Dave did run a life test on some version of it but it seems odd they are changing the design if all is well.     The same is true for the transient protection.  If Dave is going to make a statement that the meter passed cert and that's the end of the story,  then there should be no reason to change the front end.   It's good to hear they continue to develop the hardware.  I'm looking forward to seeing what they come up with.

I still believe both need to be taken care off but the biggest concern I now start to have is transparency on why the changes are happening single to double and back etc. For me there was never a good  response on why my meter had so much crud on the contacts after less then 100 power cycles. It took also quite some time to acknowledge the mechanical issue with the selector knob. All and all I am personally okay to support such an initiative, spend the money accept the risk of a possible lemon or brick but then I see room for improvement on the development process going forward. I do want to acknowledge here too that we can on this forum give plenty of updates, issue reporting or even rant on whatever we think should have been done and that in itself is worth something already.

I don't see larger companies ever becoming transparent about their designs.  It's just not a realistic goal.  At best you may get some level of independent testing like Dave showed with his toggle bot.  Maybe you will get some high level historical overview of the design after the fact but I doubt it.   

Personally, I too would have scrapped the boards and pushed on.  Just knowing that a new version is in the works may impede sales of the older model.   

Even on these forums we have read about large companies having to do recalls on their hardware.  Keysight's susceptibility problems for example.  The switch design requiring a shim was a much more telling indicator about UEI's validation process.   Brymen for example has not only told me about how they cycle test their switch designs, they have shown me video clips of their cycle jigs.  If that wasn't good enough, they sent me a meter to repeat my own cycle test on and it held up quite well.   I don't see UEI testing at this level or having the same confidence in their own products. 

[Terry01]

If i'd have known there was a newer updated model due out I would have waited rather than buy one a week or two ago! 

But there ya go… I suppose!

[GeoffreyF]

If i'd have known there was a newer updated model due out I would have waited rather than buy one a week or two ago! 

But there ya go… I suppose!

It is not a new model.  If you read the fine print in just about any specs including these, it is clearly stated that they may make improvements and tweaks which are within the original specs but somehow improve performance or contain costs.  What you complain of is routine across most products.   Really, go and check.

[Brumby]

What you complain of is routine across most products.   Really, go and check.

This is very true.

Normally people do not see this stuff happening in real time like we are with Dave's 121GW.  We see it when we ask for spare parts for an appliance or a vehicle and they ask for some very specific identifiers for subtle differences that identify exactly which version of a part is appropriate.... and we don't think twice about this.

As long as you get a product that operates within specification, you don't really have a leg to stand on.  As for any product newly released, there is usually a price for being a first adopter - which usually involves ironing out some kinks.  The switch shim being a perfect example.

[Terry01]

I only said if i'd known there was a newer model(version) due out I would have waited.

I tried to measure 89 mA in the mA range last night and the 121GW kept saying "OFL" or whatever it was, my U1273a read it no problems at all.
To be honest i'm not really bothered I will stick it on Ebay and get some of my money back as I have other more reliable meters.

I kinda liked the look and some of the features of the meter but the more I use it the more I find things I don't like about it.

If I had wanted to complain I would have messaged where I bought it but i'm really not that bothered.

A 87v I took a punt on came up so that has nailed the 121GW's coffin shut tight.

It'll be on Ebay soon! 

[GeoffreyF]

Right and there isn't a newer version or model.

The same model has received a small improvement.  This happens all the time in all sorts of electronics.  IT IS NOT A NEWER VERSION OR MODEL.   Also, this incremental improvement does not change the published specs.  From the description, it provides the meter with some stray RF noise immunity. This is a good thing but probably makes no difference for many users.   Anyone who works in a development environment can tell you that a particular make/model is always getting tweaked in subsequent manufacturing runs.

[Terry01]

Right and there isn't a newer version or model.

The same model has received a small improvement.  This happens all the time in all sorts of electronics.  IT IS NOT A NEWER VERSION OR MODEL.   Also, this incremental improvement does not change the published specs.  From the description, it provides the meter with some stray RF noise immunity. This is a good thing but probably makes no difference for many users.   Anyone who works in a development environment can tell you that a particular make/model is always getting tweaked in subsequent manufacturing runs.

Ok, so I would have waited for "the same mode that has received a small improvement" then.

I also saw the "same model has received a small improvement" has a new daughter board and a couple of other updates on it after the 700 boards they have from this run are finished.

That's what I would have waited on. If your spending near £300 you want the best for your money.... unless you are dumb!

Spend today untwisting your knickers man!

Will be interesting to see if the new boards will have a different "V" number.....

[GeoffreyF]

If you thought about what I wrote (you didn't), you would wait forever.  Not just for test equipment but for cars, microwave ovens, tv sets etc.  EVERYTHING gets tweaked from time to time.   Unless you plan on using your 121GW around intense RF fields, this improvement means nothing.

The 121GW you bought meet specs.  The later ones meet specs. You paid for something that meets specifications.   The addition of the shield is probably to mitigate support questions more than anything.  That's usually the case with this sort of thing.

Do you even know or did you even think about whether the shield would be better for your uses?   Do you even know or think about what you would have to pay for something with the same feature set as what is specified, but also with more accuracy, ruggedness, shielding or whatever?  Every product targets a price point and a perceived need. This one does.  OTOH, if you need something else, you should have bought that one.

[EEVblog]

Seeing them change from the single dimple contact to double and now back to single.  Looking at photos of the wear, I'm not convinced the meter will hold up.  Dave did run a life test on some version of it but it seems odd they are changing the design if all is well.     

That "some version of it" was the version with the shim that shipped to everyone.
Of course the "design is changing" to remove the shim, it was never intended to there. That change BTW is just the thickness of the main PCB to go back to what was intended.

[EEVblog]

It took also quite some time to acknowledge the mechanical issue with the selector knob.

It takes time to investigate stuff like this.
Fluke took a whole year to investigate and fix the GSM issue for example.

[EEVblog]

Right and there isn't a newer version or model.
The same model has received a small improvement.  This happens all the time in all sorts of electronics.  IT IS NOT A NEWER VERSION OR MODEL.

Correct. This is not a new version or model, and there is no new version or model underway. The shim will eventually be removed, and the current mods will be integrated into a new PCB, but there are no plans for other improvements or spec changes. We are more focused on getting the firmware and development system improved, and a new shared version control system is being setup with the intention that we (EEVblog) will now have visibility on firmware changes, and also the ability to eventually make changes and compile/test ourselves.

[joeqsmith]

If you thought about what I wrote (you didn't), you would wait forever.  Not just for test equipment but for cars, microwave ovens, tv sets etc.  EVERYTHING gets tweaked from time to time.   Unless you plan on using your 121GW around intense RF fields, this improvement means nothing.

The 121GW you bought meet specs.  The later ones meet specs. You paid for something that meets specifications.   The addition of the shield is probably to mitigate support questions more than anything.  That's usually the case with this sort of thing.

Do you even know or did you even think about whether the shield would be better for your uses?   Do you even know or think about what you would have to pay for something with the same feature set as what is specified, but also with more accuracy, ruggedness, shielding or whatever?  Every product targets a price point and a perceived need. This one does.  OTOH, if you need something else, you should have bought that one.

You are suggesting they went to the TI mux and changed the clamp for an RF problem?   Are you suggesting that adding a shield to make the meter less sensitive to the proximity of your hand makes it an RF problem?   

The fact that they have changed the contact design yet again tells me the switch continues to have problems, even with the shim.  We have seen two people post where the meters our of the box with shims did not work.   Granted they were replaced but why spend $300 on a meter that the switch may not hold up?  Manuals are not going to spec the switch life.  I doubt few people buying an expensive meter would consider that something as simple as the switch being a problem.   

[Terry01]

If you thought about what I wrote (you didn't), you would wait forever.  Not just for test equipment but for cars, microwave ovens, tv sets etc.  EVERYTHING gets tweaked from time to time.   Unless you plan on using your 121GW around intense RF fields, this improvement means nothing.

The 121GW you bought meet specs.  The later ones meet specs. You paid for something that meets specifications.   The addition of the shield is probably to mitigate support questions more than anything.  That's usually the case with this sort of thing.

Do you even know or did you even think about whether the shield would be better for your uses?   Do you even know or think about what you would have to pay for something with the same feature set as what is specified, but also with more accuracy, ruggedness, shielding or whatever?  Every product targets a price point and a perceived need. This one does.  OTOH, if you need something else, you should have bought that one.

Holy gwackers he's waffling on about cars and microwaves now! 

If i'd known there was a meter with updates coming I would have waited. THAT'S ALL!!

Do you want me to post you a copy of that in braille or ask Dave or Joe to make you a video up or.....

just go away...pest!

Why does there always have to be that 1 person?

[1anX]

Right and there isn't a newer version or model.
The same model has received a small improvement.  This happens all the time in all sorts of electronics.  IT IS NOT A NEWER VERSION OR MODEL.

Correct. This is not a new version or model, and there is no new version or model underway. The shim will eventually be removed, and the current mods will be integrated into a new PCB, but there are no plans for other improvements or spec changes. We are more focused on getting the firmware and development system improved, and a new shared version control system is being setup with the intention that we (EEVblog) will now have visibility on firmware changes, and also the ability to eventually make changes and compile/test ourselves.

Dave, it may not be a complete new model, but it will be a substantial Revision of the current model. The reason I did not buy another 121GW was because UEI and EEVBlog have decided to use up the remaining 700 out of spec PCBs.

While this may make some sort of financial sense to you and UEI it made absolutely no sense to me as a customer as I dont want another prototype meter. I already have my kickstarter meter that I bought because of your involvement with it. I want my test meters to last and the switch and shim solution are at best a temporary fix. Problem is that you and UEI have decided to carry on with it and let your customers carry the risk of early failure.

I wonder how much better the sales of the 121GW would be if you made it clear to customers that the new revision meters had a new PCB with hardware updates and a reliable switch with a stated switch cycle life. I dont think I am alone in deciding that an alternate meter would be a better choice until you and UEI bring this meter up to spec!

Make the responsible decision that is right for the customers and suffer a tiny financial loss on the out of spec PCBs and you will find this meter becoming a best seller. If you do it on the cheap and let your customers carry the risk IMO then you carry the risk of not having any customers.

I have a Brymen BM867s on its way and I would have preferred a properly made 121GW meter instead.

[Terry01]

Right and there isn't a newer version or model.
The same model has received a small improvement.  This happens all the time in all sorts of electronics.  IT IS NOT A NEWER VERSION OR MODEL.

Correct. This is not a new version or model, and there is no new version or model underway. The shim will eventually be removed, and the current mods will be integrated into a new PCB, but there are no plans for other improvements or spec changes. We are more focused on getting the firmware and development system improved, and a new shared version control system is being setup with the intention that we (EEVblog) will now have visibility on firmware changes, and also the ability to eventually make changes and compile/test ourselves.

Dave, it may not be a complete new model, but it will be a substantial Revision of the current model. The reason I did not buy another 121GW was because UEI and EEVBlog have decided to use up the remaining 700 out of spec PCBs.

While this may make some sort of financial sense to you and UEI it made absolutely no sense to me as a customer as I dont want another prototype meter. I already have my kickstarter meter that I bought because of your involvement with it. I want my test meters to last and the switch and shim solution are at best a temporary fix. Problem is that you and UEI have decided to carry on with it and let your customers carry the risk of early failure.

I wonder how much better the sales of the 121GW would be if you made it clear to customers that the new revision meters had a new PCB with hardware updates and a reliable switch with a stated switch cycle life. I dont think I am alone in deciding that an alternate meter would be a better choice until you and UEI bring this meter up to spec!

Make the responsible decision that is right for the customers and suffer a tiny financial loss on the out of spec PCBs and you will find this meter becoming a best seller. If you do it on the cheap and let your customers carry the risk IMO then you carry the risk of not having any customers.

I have a Brymen BM867s on its way and I would have preferred a properly made 121GW meter instead.

You won't be disappointed with the 867s. It's an awesome meter! Granted the 121GW has a few extra features but the 867s "does what it says on the tin" and everything it does, it does well!

[newbrain]

I got side tracked yesterday so didn't get to test the "hysteresis" but I will do it today for sure and post the results.

I don't think you'll get different results from what's already known.
In the linked post, for reference, the behaviour of Fluke 87V.

Just to make sure, I quickly retested with FW 1.57, for DC V (5V range) and mA (5mA range): the thresholds are still 40000-55000 counts (-20% + 10% wrt nominal 50000).

[Terry01]

I got side tracked yesterday so didn't get to test the "hysteresis" but I will do it today for sure and post the results.

I don't think you'll get different results from what's already known.
In the linked post, for reference, the behaviour of Fluke 87V.

Just to make sure, I quickly retested with FW 1.57, for DC V (5V range) and mA (5mA range): the thresholds are still 40000-55000 counts (-20% + 10% wrt nominal 50000).

No prob, I still haven't done it anyways. I will when i'm next at my bench. The difference being I have FW 1.54 installed.

[EEVblog]

While this may make some sort of financial sense to you and UEI it made absolutely no sense to me as a customer as I dont want another prototype meter. I already have my kickstarter meter that I bought because of your involvement with it. I want my test meters to last and the switch and shim solution are at best a temporary fix. Problem is that you and UEI have decided to carry on with it and let your customers carry the risk of early failure.

We are confident the shim solution will not lead to "early failure".