Author Topic: EEVBlog 121GW Discussion thread  (Read 251337 times)

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Online CDaniel

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Re: EEVBlog 121GW Discussion thread
« Reply #1650 on: November 14, 2019, 11:10:29 am »
You should read carefully what are the issues , use the meter some time and then tell us the conclusion .
I doubt your pF measurement is consistent and not drifting ...
The problem with the 50ohm range are the last 2 digits or so , for small resistors ... even when you short the leads the reading is very inconsistent .
 

Offline beanflying

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Re: EEVBlog 121GW Discussion thread
« Reply #1651 on: November 14, 2019, 01:11:48 pm »
You should read carefully what are the issues , use the meter some time and then tell us the conclusion .
I doubt your pF measurement is consistent and not drifting ...
The problem with the 50ohm range are the last 2 digits or so , for small resistors ... even when you short the leads the reading is very inconsistent .

So you start with knowing the issues, use the meter and then reach a conclusion based on what exactly? :palm: Your non scientific method is truly amazing and a wonder to behold :o

What J-R should maybe look at FIRST is what are the accuracy or tolerance of the Caps he is playing with and do his meters confirm that the combined accuracy is in the correct ballpark. You can test with as many meters as you like but without a 'known' starting point or some sort of reference all the readings are just relative to each other. Stating meter X is better than Y is  :bullshit: without a reference or known standard to compare against. The best you can do is really give a best guess yeah or nay as to accuracy at the extremes of spec.

The drift is another matter and as per the post I linked to I found that to be the case on small Caps nearly a year ago https://www.eevblog.com/forum/testgear/eevblog-121gw-discussion-thread/msg2051194/#msg2051194 If you want to go there and be stable best look elsewhere for a meter. This you can make observations about drift or non shorted readings compared to shorted ones before readings as they are just comparative rather than a finite number. Buy an LCR meter and do it properly if you NEED these readings to be accurate otherwise it is just NOISE.

Want to measure small resistances accurately buy a Millohm meter or certainly one with four wire measurement. It is 'sensible' to use a low current on a battery powered meter as a compromise so stop exaggerating and making overstated claims. My Milliohmmeter for example kicks the butt of my 34401A and 34461A as it pumps up to 1A on the lower ranges as a test current.
« Last Edit: November 14, 2019, 01:36:32 pm by beanflying »
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Online CDaniel

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Re: EEVBlog 121GW Discussion thread
« Reply #1652 on: November 14, 2019, 03:08:40 pm »
For fanboys ... Fluke 289  multimeter use 10mA for 50ohm range , of course you have to be Fluke to realize this ...  ;D

In capacitance mode , when something drifts , the reading is not consistent +-50pF or so , it's shitty accuracy all day long . It can't be trusted .
And please don't tell me what to buy , if you don't know how a good design meter should behave  :-X  ,  although probably even a chinese crap meter doesn't have this capacitance issue .
 


« Last Edit: November 14, 2019, 03:14:47 pm by CDaniel »
 
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Offline daveyk

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Re: EEVBlog 121GW Discussion thread
« Reply #1653 on: November 15, 2019, 03:11:17 pm »
All the meters are like yours with slow resistance autorange . The 50ohm range  is not stable because they design it with very low measurement current and insanely high ADC gain .  This can't be fixed in firmware .

So CDDaniel, you are basically telling me the Resistance mode of the 121GW is just plain bad?  It does work okay, in manual resistance range.  I just can't tell watch range I am in or when I cycle back to auto when pushing the range switch.  It would be nice for some sort of easier to view enumerator was on the display.  There is the "AUTO", but when range is pushed that goes away and I have no idea what range I am in, and NO, I am not reading the manual to know what ranges it toggles through.  Why should I have to do that?  Any other meter displays what range it is on! Okay maybe that bottom analog scale might show it?... It is hard to read.  Why not put something where the AUTO is? So I press range one time and I am on the 50 ohm range? Leads together read 0.000 ohms. Push range again, and it stays on 50 ohms , but reads 0.50, no .204, just slowly drifts up. Push range again, and I am on 500 ohm range? Put leads together and it reads 0.00, after a few seconds of braiding down to 0.00. Push range again and it changes from 500 ohm to 5 ohm range? 0.0000 K ohms with leads together. Range again: 50 ohm range, again. Range again, stays on 500 ohm range, Leads together, it takes about 3 seconds to read 0.00.   I could go on, it is just difficult to figure this thing out.  It may be fantastic but it is not natural to use.  I push Range many times and it does not go back to auto.  Maybe it's cycling through the various ranged, but it so hard to tell when to stop.  That could be fixed in Firmware.

Dave
 

Online CDaniel

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Re: EEVBlog 121GW Discussion thread
« Reply #1654 on: November 15, 2019, 04:51:18 pm »
The issues I see with resistance mode
1 - slow autorange , this is improving with every firmware update
2 - in 50ohm range the last 2 digits are pretty useless . Every time you short the leads you get different reading and fluctuating .
3 - any range is more or less affected by mains noise , if you touch the probes . Of course this is subjective as some people have "quiet" labs , so for them is ok .
 

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Re: EEVBlog 121GW Discussion thread
« Reply #1655 on: November 15, 2019, 11:55:27 pm »
So CDDaniel, you are basically telling me the Resistance mode of the 121GW is just plain bad?  It does work okay, in manual resistance range.  I just can't tell watch range I am in or when I cycle back to auto when pushing the range switch.  It would be nice for some sort of easier to view enumerator was on the display.  There is the "AUTO", but when range is pushed that goes away and I have no idea what range I am in, and NO, I am not reading the manual to know what ranges it toggles through.  Why should I have to do that?  Any other meter displays what range it is on! Okay maybe that bottom analog scale might show it?... It is hard to read.  Why not put something where the AUTO is?
\

Seriously?
The 121GW works like every other auto ranging meter in existence. Press Range and the fixed range annunciators are clearly displayed on the right hand side.

Quote
I push Range many times and it does not go back to auto.

You hold down the Range switch for a few second to go back into Auto mode.
 

Offline J-R

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Re: EEVBlog 121GW Discussion thread
« Reply #1656 on: November 16, 2019, 07:46:16 am »
The issues I see with resistance mode
1 - slow autorange , this is improving with every firmware update
2 - in 50ohm range the last 2 digits are pretty useless . Every time you short the leads you get different reading and fluctuating .
3 - any range is more or less affected by mains noise , if you touch the probes . Of course this is subjective as some people have "quiet" labs , so for them is ok .

1 - Agreed, "slow" is a valid term to use.  I typically grab another meter for rapid resistance tasks, but I trust the 121GW to give me an accurate reading if necessary.

2 - In the 50 Ohm range, the accuracy at best is within 20 counts in either direction, so the last digit IS useless and the second to the last digit is effectively useless.  So I don't think your point is valid.

3 - Why would you be touching the probes if you care about accuracy?  I think this point is also invalid.

 

Offline J-R

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Re: EEVBlog 121GW Discussion thread
« Reply #1657 on: November 16, 2019, 08:42:07 am »
What J-R should maybe look at FIRST is what are the accuracy or tolerance of the Caps he is playing with and do his meters confirm that the combined accuracy is in the correct ballpark. You can test with as many meters as you like but without a 'known' starting point or some sort of reference all the readings are just relative to each other. Stating meter X is better than Y is  :bullshit: without a reference or known standard to compare against. The best you can do is really give a best guess yeah or nay as to accuracy at the extremes of spec.

I suppose what you are saying is technically valid, but we can also consider probabilities, statistics, logic, reason, etc.  If I'm standing outside my house and my GPS says I'm 2,300' under sea level, I can just look left and right and know that my GPS is faulty no matter what calibration certificate is stuck to it, unless we all live in The Matrix and nothing is real.

So if I buy a few random capacitors from various suppliers, measure each one individually using multiple devices to check their claimed values, then add them together in parallel and the values are still reasonable, then the probability of everything being completely wrong is tiny to the point of being nearly impossible.  Or I'm living in the Matrix and nothing is real.  I know what I'm going with...
 

Offline J-R

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Re: EEVBlog 121GW Discussion thread
« Reply #1658 on: November 16, 2019, 10:32:51 am »

So CDDaniel, you are basically telling me the Resistance mode of the 121GW is just plain bad?  It does work okay, in manual resistance range.  I just can't tell watch range I am in or when I cycle back to auto when pushing the range switch.  It would be nice for some sort of easier to view enumerator was on the display.

The operational characteristics of the 121GW are probably more hen-pecked than any other device out there and you can search the forums for specific tasks you might want to perform to get more information.


If the meter is in Auto Range mode, then pressing the Range button once will disable Auto Range and the meter will STAY in the current range.  So if you short the leads in Auto mode, it will end up in the 50 Ohm range and pressing the Range button once will set it there.  Similarly, if the leads are OPEN, then it will end up in the 50M Ohm range and pressing the Range button once sets it there.

Subsequent Range button presses cycles through the ranges, in order, as listed in the manual (page 19).

If a value is displayed on the meter, you can observe the decimal point and the "M" or "k" to immediately see the resistance value.  If OFL is displayed, you can reference the small number on the bottom right of the display as it cycles between 5, 50 and 500 along with the units display (M, k, etc.) to determine what range you are in.

« Last Edit: November 16, 2019, 10:34:37 am by J-R »
 

Offline 1anX

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Re: EEVBlog 121GW Discussion thread
« Reply #1659 on: November 16, 2019, 08:48:09 pm »
Hey Dave, or anyone from the EEVBlog Store!
Can you please make clear what version of the meter is currently in stock and being sold from EEVBlog Store.
Dave, how about a technical run down on what the latest hardware revision of the meter does and how the meter has changed over the period of time since it first went on sale!
It seems you provided heaps of great info on this meter initially, (pre-sales) and I for one found it interesting and informative.
The meter has a few problems and didn't live upto initial expectations, but I'm still interested as an owner and as an early adopter/supporter of your collaborative effort with UEI.
My wish is that you would come forward and update the buyers of this meter on just what progress has been made!
The worst thing IMHO is that you have become silent on the technical progress of this meter. Your silence and not keeping the community around this meter informed is damaging your reputation as an advocate for honest unbiased technical reviews.
Looking forward to hearing from you with an updated EEVBlog on the current state of play with the 121GW meter!
 

Offline joeqsmith

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Re: EEVBlog 121GW Discussion thread
« Reply #1660 on: November 17, 2019, 12:34:00 am »
I wrote Dave today after he suggested that I "... should have asked first!" that it's really up to him to communicate with his customers, not the other way around.   

In my case, the entire drama could have very easily been avoided with a simple note in the ad.   Again, to be clear, I was never looking for special treatment.  I want the meters that any one else placing an order would get.   What I was not expecting was to find out that a newer major revision of the meter was available a few months before I bought mine and I received the old hardware, without notification.    This is just bad business practice and pointing the finger at the customer is certainly not a step in the right direction.   They are certainly free to handle their affairs as they see fit, but as a past customer it won't happen again.     

I suggest major revision as the PCB revision had changed and the shim had been removed, along with other changes.  Any changes to that switch design IMO is major. 

While we are off to a rocky start with this review, you can be assured I will remain unbiased.  These tests are data driven, not drama driven. 
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline ornea

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Re: EEVBlog 121GW Discussion thread
« Reply #1661 on: November 17, 2019, 02:21:23 am »
I think statistically there is value in using many meters to compare.

I was in a metrology lab (same one dave visited) one day and  asked how the calibrate their top level equipment (The exact equipment may have been measuring time, I cant remember). They said they compare and reference against same level of tier of equipment around the world and if they agree then its calibrated.
 

Offline e0ne199

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Re: EEVBlog 121GW Discussion thread
« Reply #1662 on: November 17, 2019, 03:25:59 am »
Hey Dave, or anyone from the EEVBlog Store!
Can you please make clear what version of the meter is currently in stock and being sold from EEVBlog Store.
Dave, how about a technical run down on what the latest hardware revision of the meter does and how the meter has changed over the period of time since it first went on sale!
It seems you provided heaps of great info on this meter initially, (pre-sales) and I for one found it interesting and informative.
The meter has a few problems and didn't live upto initial expectations, but I'm still interested as an owner and as an early adopter/supporter of your collaborative effort with UEI.
My wish is that you would come forward and update the buyers of this meter on just what progress has been made!
The worst thing IMHO is that you have become silent on the technical progress of this meter. Your silence and not keeping the community around this meter informed is damaging your reputation as an advocate for honest unbiased technical reviews.
Looking forward to hearing from you with an updated EEVBlog on the current state of play with the 121GW meter!

i agree with this..i honestly see that this meter actually has so many potentials to be one of the great meters but somehow it is constantly plagued with so many major bugs and it takes too much time for a fix...i really hope so much that the problem is not related with hardware...i hope that people who made this meter should try fix every bugs that exist in this meter and if they aren't able to do it anymore (or probably unable to do it) then just release its source code to the public so that everyone can work together to fix the problem of this meter...
 

Online EEVblog

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Re: EEVBlog 121GW Discussion thread
« Reply #1663 on: November 17, 2019, 07:54:23 am »
I wrote Dave today after he suggested that I "... should have asked first!" that it's really up to him to communicate with his customers, not the other way around.   
In my case, the entire drama could have very easily been avoided with a simple note in the ad.   

When you placed your order I had not received the new meters and still had a couple of boxes of old meters, so your order was shipped as standard.
In terms of getting the latest build your order was a simple case of terrible timing, that once again could have been avoided if you simply had asked. You seemed very upset and angry that you got an older version and I offered to replace them but you refused, and that's fine, I have no problem with it, your choice. I'm not sure how many times I'm going to have to repeat saying this.

To be very clear, there are no specification changes, no operational changes, and no rating change between meters. Most customers would not care about every minute detail you care about, to them it's the same spec meter with the same performance, the same features, and the same warranty. They are fully independently tested by ETL.

Quote
I suggest major revision as the PCB revision had changed and the shim had been removed, along with other changes.  Any changes to that switch design IMO is major. 

This change has been know about since almost day one. There were 4000 assembled PCB's from the first Kickstarter batch, and I stated publicly at the time that all those 4000 boards would be used up until stock was exhausted and then the next production run would use the correct 1.6mm PCB that would not require the shim.
 

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Re: EEVBlog 121GW Discussion thread
« Reply #1664 on: November 17, 2019, 08:07:09 am »
Hey Dave, or anyone from the EEVBlog Store!
Can you please make clear what version of the meter is currently in stock and being sold from EEVBlog Store.

I have I think a box and half of the original stock left.
I just got in a shipment of the latest build, that AFAIK Welectron do not have yet. FYI, I have no no visibility in what stock Welectron have or when they got it, they order direct from UEi as required, but I'm fairly sure they don't have the new 1.6mm PCB. So once the box and half or whatever is gone I'll start selling the new build.

This new build (v.02 -1910 PCB) is the first run after the 4000 Kickstarter boards were assembled, changes are (IIRC):
1) Correct 1.6mm PCB as intended (the KS PCB was unknowingly thinner from the manufacturer, hence the shim)
2) Plated hole on the knob
3) The protection transistors that were fitted onto small daughter boards are now integrated into the PCB.
4) Battery terminals are now smaller
5) Supplied with UEi silicone probes now instead of Brymen.


 
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Online thinkfat

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Re: EEVBlog 121GW Discussion thread
« Reply #1665 on: November 17, 2019, 09:34:50 am »
In my case, the entire drama could have very easily been avoided with a simple note in the ad.   Again, to be clear, I was never looking for special treatment.  I want the meters that any one else placing an order would get.   What I was not expecting was to find out that a newer major revision of the meter was available a few months before I bought mine and I received the old hardware, without notification.    This is just bad business practice and pointing the finger at the customer is certainly not a step in the right direction.   They are certainly free to handle their affairs as they see fit, but as a past customer it won't happen again.     

If I order some device, be it directly from the OEM or through a distributor, I won't know either whether I have the very latest revision of the device. Unless I specifically ask for a specific revision I have no leverage anyway, it will be from whatever stock is in the warehouse at the time. If I look at listings at Distrelec or Batronix or wherever, they don't even mention specific revisions. They will assume, rightfully, that all gear the receive from the OEM are meeting advertised specifications. If not, there would be a update notification or even a recall option.

Dave says there was no update to the published spec, so I don't quite see what's the ruckus...
 

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Re: EEVBlog 121GW Discussion thread
« Reply #1666 on: November 17, 2019, 09:51:52 am »
Dave says there was no update to the published spec, so I don't quite see what's the ruckus...

There was no ruckus with the BM235 which underwent a couple of hardware revisions and half a dozen (non-upgradeable) software updates
 

Offline ggchab

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Re: EEVBlog 121GW Discussion thread
« Reply #1667 on: November 17, 2019, 09:53:49 am »
If a production meter is a production meter and specifications have not changed, tests results should be the same whether it's the latest hardware version or not. Or am I missing something ?

On the other hand, I am wondering why spending time and money to change something that already meets specifications ? (except thickness of the PCB to avoid the patch)

So, it would be interesting if Dave could simply send another 121GW with the latest hardware to Joe Smith so that he could make real comparisons. But I don't think this will ever happen  ???

Also, as Joe already said, I don't see why he would deserve a better service than other users ? He bought his meters the same way we all did. May we swap our 121GW with one having the latest changes ?
 

Online CDaniel

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Re: EEVBlog 121GW Discussion thread
« Reply #1668 on: November 17, 2019, 12:48:51 pm »
But who said that newer meters behave better ? As far I can see my meter always could measure 150pF and Joe's newer version out of the box couldn't .
I'm wondering how is working now , has recovered itself ? In the latest video 1nF was close with the other meters , not 1nF - 150pF
« Last Edit: November 17, 2019, 12:51:31 pm by CDaniel »
 

Offline jancumps

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Re: EEVBlog 121GW Discussion thread
« Reply #1669 on: November 17, 2019, 01:49:48 pm »
...

On the other hand, I am wondering why spending time and money to change something that already meets specifications ? (except thickness of the PCB to avoid the patch)
...

These are answered a few posts above: move protection transistors from separate little PCB to main PCB, thickness of PCB, the hole for the knob plated, smaller springs for the batteries.
Costs are saved because no daughter board and shim needed, while specs stay the same.
« Last Edit: November 17, 2019, 01:51:21 pm by jancumps »
 
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Offline joeqsmith

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Re: EEVBlog 121GW Discussion thread
« Reply #1670 on: November 17, 2019, 02:59:14 pm »
But who said that newer meters behave better ? As far I can see my meter always could measure 150pF and Joe's newer version out of the box couldn't .
I'm wondering how is working now , has recovered itself ? In the latest video 1nF was close with the other meters , not 1nF - 150pF

I suspect there is both a software and hardware problem when measuring small capacitor values,  which is what I was showing in the last segment.   No the meter has not magically healed itself.   The new hardware could very well correct one of the problems.
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline daveyk

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Re: EEVBlog 121GW Discussion thread
« Reply #1671 on: November 17, 2019, 03:09:05 pm »
Hello Joe,  I found your videos on YouTube; nice.  Is the older board the reason, they were on sale on the EEVBLOG store verses getting them from another source with the newer board?  Is there anything other than the board, switch and shielding?
 

Offline joeqsmith

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Re: EEVBlog 121GW Discussion thread
« Reply #1672 on: November 17, 2019, 03:21:07 pm »
This new build (v.02 -1910 PCB) is the first run after the 4000 Kickstarter boards were assembled, changes are (IIRC):
1) Correct 1.6mm PCB as intended (the KS PCB was unknowingly thinner from the manufacturer, hence the shim)
2) Plated hole on the knob
3) The protection transistors that were fitted onto small daughter boards are now integrated into the PCB.
4) Battery terminals are now smaller
5) Supplied with UEi silicone probes now instead of Brymen.


We know there was a least one meter sold without a shim using PCB revision V.02-1905.   Like my old hardware, these also appear not to have a plated hole for the knob.  Both clamps in question are using different components than seen on my old hardware and are located on mezzanine boards.   

According the the person who supplied the picture, this hardware was available at least two months prior to me placing an order. 

We have shimmless to shim and back to shimless.   No shield to shield.   Then we have  diodes to TVS to small transistor mezzanine to a large transistor mezzanine onto large transistor integrated clamps.      They were changing the switch contacts as well.   At some point they have some sort of hybrid using both double single dimples.  My old hardware is all single dimple.  No idea what's in there now.

I think the difference is Brymen seems to do a decent job with their testing.  They make small corrections once a problem has been identified, not major reckless changes.  From what I have seen so far, there is no comparison in the quality.
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline joeqsmith

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Re: EEVBlog 121GW Discussion thread
« Reply #1673 on: November 17, 2019, 03:31:09 pm »
Hello Joe,  I found your videos on YouTube; nice.  Is the older board the reason, they were on sale on the EEVBLOG store verses getting them from another source with the newer board?  Is there anything other than the board, switch and shielding?
Thanks. 

Your first question is for Dave.  You can check the store  https://www.eevblog.com/product/121gw/    and see if they have changed the ad to include details about the revisions and what you are buying.   If something goes on sale, I wouldn't normally jump to the conclusion it is old stock.   Normally this would be part of the ad.   

Your second question is difficult for me to answer as it's relative to what?  I don't have one of the original kick start meters to compare it with.  They don't maintain the public documentation (schematics).   Read my last post which includes some of the things I have noticed from what other's have posted. 
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline 1anX

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Re: EEVBlog 121GW Discussion thread
« Reply #1674 on: November 18, 2019, 11:05:10 pm »
Dave has a new video up on auto-ranging speed!

 


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