EEVBlog 121GW Discussion thread

[amspire]

For reference when referring to the rotor, that is the plastic carrier for the contact fingers, the PCB is the Stator and the knob would be the 'clicker plate' just like any rotary wafer switch assembly.

You are right. I used the words switch rotor when I meant knob. I have corrected it.

Okay when making it worse are you referring to the small sleeve or the PTFE under the circlip ?.
For the sleeve i disagree that any additional stress is being applied to the contacts or the PCB. The dimensions of it are carefully chosen by measurement to only
apply enough pressure to the plastic fingers of the rotor body to the PCB hole reducing only lateral free play ,(which in my opinion is excessive ), to a minimum without
adversely effecting the effort required to rotate. This mechanical change guarantees alignment of the switch contacts on the rotor with the PCB stator and how will this
introduce ant further stress on the contacts.

I believe that when you put the PTFE under the circlip, then the circlip does push downwards on the switch rotor slightly. Not much deflection, but I don't think anything you do on the knob should be pushing the rotor up and down.

The way I have fixed my meter, there is a clear gap between the circlip and the rotor.

As far as the sleeve goes, I do not think you need any reduction in play of the rotor since the hex shaft from the knob locates the position of the rotor. You should have a knob that is centred and doesn't wobble.

If you need the sleeve to help stop the knob from wobbling, then I think you are making the switch rotor do something it shouldn't be doing. Any rotating pressure on the knob is transferred directly to the rotor and the PCB. There is no need for this to be so.

 Now for the PTFE under the circlip, has anyone measured the distance from the top of the rotor body to the underside of the circlip to determine how much distance
there actually is ?. I will admit it has crossed my mind and yet I did not actually do it myself , so as soon as I can I will take the meter apart again I will attempt to get some
measurement done there and post back, as well as try the knob without the PTFE spacers to see if only the sleeve cured my issue or it is indeed needed to apply light pressure to the rotor.
If even that is actually happening with the spacers installed.

I just observed some deflection, but I didn't measure the amount. I had already decided to go a different way. The best way to measure this deflection may be to measure the height of the rotor clip above the PCB on the component side.

What struck me is that when the front case was away from the switch, the knob was really loose - much worse then when attached to the switch.

The problem is threefold - the circlip allows a big vertical movement, the knob sides have too much clearance and the knob moulding taper is all wrong. The knob hole in the case gets wider at the top, and so the knob should also get wider and not narrower at the top. I wanted a knob that on its own wasn't wobbling and that didn't rely on the tightness of the circlip to stop the wobbling.

Now both our "fixes" are definitely not approved by Dave or the manufacturer, so they are both just our own opinion of a solution. Given that it seems that a new knob is coming, it is probably best to wait if you have no problem right now - just be careful with the knob.

[lowimpedance]

Indeed the fixes we have done for our own are for a bit of tinkering and not 'approved'. And of course I will use the redesigned assembly when it arrives.
But as I have clearly found on my meter the was a direct link to PCB flexure from only small movement of the probe inputs that caused major issues
on the ohm/diode modes of that switch position that it was completely unusable until I did my version of a fix and now in the interim the functions work.
(note that my 121 meters knob was quite 'wobbly' to start with! so I am not convinced its just the knob and not also the rotor slop at play here too.).
Now purely for my own edification I will see what effect the sleeve has without the PTFE packing. Is most surely not going to damage my meter to have a play
while I wait for the 'approved ' replacement part.

[ChrisG]

Indeed the fixes we have done for our own are for a bit of tinkering and not 'approved'. And of course I will use the redesigned assembly when it arrives.
But as I have clearly found on my meter the was a direct link to PCB flexure from only small movement of the probe inputs that caused major issues
on the ohm/diode modes of that switch position that it was completely unusable until I did my version of a fix and now in the interim the functions work.
(note that my 121 meters knob was quite 'wobbly' to start with! so I am not convinced its just the knob and not also the rotor slop at play here too.).
Now purely for my own edification I will see what effect the sleeve has without the PTFE packing. Is most surely not going to damage my meter to have a play
while I wait for the 'approved ' replacement part.

Gents, all of this is fine for the wobbly knob and rotor action. However it does not address the wear of the knob axis within the PCB. The gunk which was on my PCB tracks (or does it?).

[videobruce]

I hate to ask, but what is so special about this DMM??? 
One would think by all the posts in now THREE sticky threads that it was the 3rd coming, especially considering these threads are only 3 weeks old.   

Who is the manufacture?  I don't see it listed in that DMM thread thou that hasn't been updated in 8 months.

[nidlaX]

I hate to ask, but what is so special about this DMM??? 
One would think by all the posts in now THREE sticky threads that it was the 3rd coming, especially considering these threads are only 3 weeks old.   

Who is the manufacture?  I don't see it listed in that DMM thread thou that hasn't been updated in 8 months.

There are three stickies and a ton of posts because it's Dave's multimeter, so this is the primary place to discuss it.

If you haven't learned by now that the multimeter is made by UEi, then you aren't trying hard enough.

[videobruce]

Now I have learned.
Of course if there was specific info, other than some U-Boob video as to whom was making/selling this and a link where to buy it, it would of been apparent. This should of been in the OP, without the ASSUMPTION that EVERYONE here already knows about another multimeter of which there are a hundred already in existence and hundreds more discontinued.

That's almost as bad as using acronyms & abbreviations (that aren't COMMON and often used) in documents without at least stating once what they stand for. 

"EEVBlog" doesn't ring a bell as a importer or manufacture.   

[nidlaX]

Now I have learned. O
Of course if there was specific info, other than some U-Boob video as to whom was making/selling this and a link where to buy it, it would of been apparent.

There was an announcement thread. There is a Kickstarter page. There is Google.

I recommend learning how to use the Internet.

[mikeselectricstuff]

"EEVBlog" doesn't ring a bell as a importer or manufacture.   

The clues are out there...

[lowimpedance]

Indeed the fixes we have done for our own are for a bit of tinkering and not 'approved'. And of course I will use the redesigned assembly when it arrives.
But as I have clearly found on my meter the was a direct link to PCB flexure from only small movement of the probe inputs that caused major issues
on the ohm/diode modes of that switch position that it was completely unusable until I did my version of a fix and now in the interim the functions work.
(note that my 121 meters knob was quite 'wobbly' to start with! so I am not convinced its just the knob and not also the rotor slop at play here too.).
Now purely for my own edification I will see what effect the sleeve has without the PTFE packing. Is most surely not going to damage my meter to have a play
while I wait for the 'approved ' replacement part.

Gents, all of this is fine for the wobbly knob and rotor action. However it does not address the wear of the knob axis within the PCB. The gunk which was on my PCB tracks (or does it?).

Are you sure the ''gunk' on the PCB is related to the rotor fit/action in the hole of the PCB ?. Looks more like its related to the contacts wiping action on the gold plated traces, unless I'm
looking at the wrong picture!.
If its related to the abrasion of the rotor plastic there should be noticeable scrape marks on the plastic fingers of the rotor that pass through the PCB hole. One would think this type of multimeter
switch rotor construction would be a problem no matter who's brand it is.

[lowimpedance]

Followup to the above where I said ;

Now purely for my own edification I will see what effect the sleeve has without the PTFE packing.

I have removed the packing and left off the circlip too.  So testing of the diode mode, (which failed to work on my meter when received), it still works with no issues at all from any probe movement or
any lateral or wiggling movement of the knob. So it appears at least for my meter the sleeve HAS fixed the issue I had and the PTFE packers are in fact not needed.
Thus too much lateral free play of the rotor is the problem and not contact pressure on the PCB. (and I'll bet its the same with all others meters doing odd things on other ranges that are not firmware related.).


Using a piece of 0.85mm thick PTFE sheet cut in a thin strip and bent to go into the space between the rotor top and top housing I can see the distance (tested by inserting the 'shim' where the knob would have been) to be close to 0.9mm.
The circlip is 0.6mm thick. So in the stock production meters there is no contact between rotor and circlip.
Picture showing the knob removed from the assembled meter and using a teflon shim to measure the gap between the rotor and hosing.

Edit: To note also the knob is much less 'wobbly or free' in its movement when seated with the sleeve in place and no packing under the circlip. (or even the circlip ! )

[Kean]

I forgot to mention that a couple of days ago I dumped the batteries out of a set top box remote control I need to return and was surprised to see that they were made by UEI. I wonder if the 121GW comes with a UEI battery?

UEI batteries in a remote control would be from a different UEI: Universal Electronics vs UEi Test Instruments

[1anX]

For anyone interested in Dave candidly discussing the 121GW issues:

 https://theamphour.com/377-debugger-vs-printeffer/

Spoilers: Dave chuckles over the irony of the slow resistance settling time and what he has said about other meters.  He also noted that the slowness was introduced in a late firmware update and he noted that they should have had a formal list of tests to be done for each release.

I'm standing by for the US deliveries....

I had a listen to it myself today, as still no word from Dave or UEi on the current state of the meter's repair and updated firmware!

Seems on the theamphour.com interview, Dave says that UEi have a fix for the hardware switch issues. All the suggestions on this forum thread seem to indicate that a fix is necessary and probably straightforward to implement.

Can anyone provide info on what UEi have come up with to fix the wobbly switch and intermittent contact issue?

[amspire]

Can anyone provide info on what UEi have come up with to fix the wobbly switch and intermittent contact issue?

When UEi release fully tested fixes and upgrades, Dave will announce it.

Like it or not, it does not help anyone if companies release updates and fixes in a bit of a panic. It doesn't help if companies promise solutions before they actually have the complete solution. This is a Kickstarter meter - it is close to a prototype unit. They have made the initial 500 or so meters and found a few problems. If you want a great meter, give UEi time to resolve the issues in a proper manner. This is a normal process. A fix for the knob probably means a new moulding and then it should be properly tested to decide if the mark II knob is right or not. It might be too tight for a good feel. They might have to try a third or fourth knob to get it right. Software updates can actually mean major rewrites that then need to go through a full quality audit and testing.

Do you actually have intermittent contact issues yourself? If not, just use the meter, and when the updates come in a week or a few months, you will have a better meter.

[EEVblog]

For anyone interested in Dave candidly discussing the 121GW issues:

 https://theamphour.com/377-debugger-vs-printeffer/

Spoilers: Dave chuckles over the irony of the slow resistance settling time and what he has said about other meters.  He also noted that the slowness was introduced in a late firmware update and he noted that they should have had a formal list of tests to be done for each release.

I'm standing by for the US deliveries....

I had a listen to it myself today, as still no word from Dave or UEi on the current state of the meter's repair and updated firmware!

For the third or fourth time now, when I know it's all done and dusted, you'll know.
This stuff doesn't take days to do, it can take weeks.
I have just got a new version that fixes the Low-Z high frequency issue, but I have not tried it yet.
So I think that's most of the software issues now fixed, but we will not be dribbling out updates every few days and they solve an issue, there will be one big update that includes all the software bug fixes.
The hardware switch issue is still waiting on parts delivery.

Can anyone provide info on what UEi have come up with to fix the wobbly switch and intermittent contact issue?

They have tweaked the dimensions of the white plastic spring assembly and switch assembly I believe.

[Brumby]

For those who might miss it ... I will highlight a couple of points...

For the third or fourth time now, when I know it's all done and dusted, you'll know.
This stuff doesn't take days to do, it can take weeks.

If you seriously look at what is involved in the manufacture of an even moderately complex product, this should be no surprise at all.

So I think that's most of the software issues now fixed, but we will not be dribbling out updates every few days and they solve an issue, there will be one big update that includes all the software bug fixes.

Getting people to re-flash the firmware 20 times in a month is NOT conducive to a high standard of testing - nor is it an appealing prospect to owners.  It is also bad form.

[BravoV]

Getting people to re-flash the firmware 20 times in a month is NOT conducive to a high standard of testing - nor is it an appealing prospect to owners.  It is also bad form.

Kids these days tend to love frequent updates, no matter how shitty the update, as long the manufacturer keep pumping out updates every week, they will be happy, just don't know why. 

Just look at popular PC forums on motherboards when these tons of whiners cried/cursed/begged etc for frequent BIOS update just for minuscule non critical bug. 

Prolly they already used to live with their gadgets that do frequent updates like in smartphone apps ? or worst Win 10 syndrome ? 

[nidlaX]

Getting people to re-flash the firmware 20 times in a month is NOT conducive to a high standard of testing - nor is it an appealing prospect to owners.  It is also bad form.

Just look at popular PC forums on motherboards when these tons of whiners cried/cursed/begged etc for frequent BIOS update just for minuscule non critical bug. 

While I generally agree with you, I disagree that firmware updates for this meter in its current state should be aggregated for months before being released.

1. The meter is essentially in a beta phase of release right now, so frequent updates and testing will help the manufacturer find and fix issues more quickly. Issues are expected to be the norm at this stage.
2. The people who wanted first dibs on this meter are also probably the ones who will tolerate more frequent updates. Better to do rapid revisions with 500 willing guinea pigs now than later on when customers expect a mature product.
3. You can always let people opt-in to a faster firmware release channel. If there's a significant new issue or regression, you can always roll back.

[amspire]

While I generally agree with you, I disagree that firmware updates for this meter in its current state should be aggregated for months before being released.

1. The meter is essentially in a beta phase of release right now, so frequent updates and testing will help the manufacturer find and fix issues more quickly. Issues are expected to be the norm at this stage.

But the manufacturer also has to provide warranty on these meters and they do not want to have to support 100 different versions of updates.

They haven't released any firmware update officially yet. Until they do, they can still change things. It could be that today, there is a meeting at UEi right now where someone is saying "Our autoranging code is not really capable of managing the needs of this meter, particularly in VA mode. There is no way to fix it. We really have to rewrite the autoranging from scratch."

The last thing they would want is a flood of public complaints, Youtube videos, posts and emails about problems with previous updates that will become absolutely irrelevant when the new code is in place.

[IanB]

This stuff doesn't take days to do, it can take weeks.

While I generally agree with you, I disagree that firmware updates for this meter in its current state should be aggregated for months before being released.

The suggestion was weeks, not months. Let's not exaggerate.

[Brumby]

For some of the "Now" generation, even saying "tomorrow" will get you howls of disapproval...

[Brumby]

... so frequent updates and testing will help the manufacturer find and fix issues more quickly.

Except ... that it won't - necessarily.

Each time a revision of any software is made - especially firmware in a device like this - it should undergo full regression testing to make sure that some little tweak in one place didn't break something somewhere else.

Also, an interim solution may demand a particular behaviour in some aspect of operation - but it is later found that this interim solution to one problem caused other issues.  These other issues could then dictate a different solution, with a different behaviour.

No.  As a software developer, I would NOT be happy about releasing something half-baked, especially when there is pressure to get the whole thing sorted.  The rigmarole in just getting a release out would be a waste of resources.

[EEVblog]

[amspire]

If a rushed update corrupted the calibration data in the meter, then UEi or Dave would have to organise the recalibration of hundreds of meters located around the world under warranty. Releasing firmware is definitely not to be taken lightly.

[1anX]

Hey, many thanks Dave!

That's the Dave I know and love watching. I for one enjoy watching the meter development process and it getting tested by you along the way. No need for a media blackout and a code of silence being enforced. We members on these forums are mostly technical people and supporters of yours and appreciate being kept in the loop.

Bring us along for the ride as it develops, so we can all learn from the experience.

IMO your selling this meter's attributes short by not showing the features off as they are fixed. I say more videos highlighting what goes on technically to rectify the bugs. Don't discount the tremendous interest in this product. Make these early shortcomings its strengths by highlighting the fixes. I would have thought this is a video bloggers dream opportunity!

Those who seem to want to know nothing about the meters progress, and are more than happy to wait weeks without an update, well they can just view the thread once a month or so. That way all forum members/backers and supporters of the kickstarter project are catered for. 

Food for thought, Dave?

[amspire]

Bring us along for the ride as it develops, so we can all learn from the experience.

IMO your selling this meter's attributes short by not showing the features off as they are fixed. I say more videos highlighting what goes on technically to rectify the bugs. Don't discount the tremendous interest in this product. Make these early shortcomings its strengths by highlighting the fixes. I would have thought this is a video bloggers dream opportunity!

Those who seem to want to know nothing about the meters progress and are more than happy to wait weeks without an update can just view the thread once a month or so. That way all forum members/backers and supporters of the kickstarter project are all catered for. 

Food for thought, Dave?

Would you like to see daily posts saying "There is no update today" ?

Quite often, there is not much more to say until there is an update released. Dave does actually say a fair bit about the multimeter, but it is spread across many threads. It almost sounds like you want to see a live video feed of Dave discussing problems with UEi. Just don't hold your breath waiting for it.