Author Topic: EEVblog 121GW Multimeter Issues  (Read 223900 times)

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Offline Scottjd

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Re: EEVblog 121GW Multimeter Issues
« Reply #1075 on: December 05, 2019, 07:46:07 am »
Glad to see Joe also was able to capture this  :phew:, now with multiple confirms of the issue my guess is the manufacture will look into the issue and hopefully resolve it. Like Joe said, that’s why we test.

The weird thing is trying to make it repeatable. I did capture another 44K logs and it didn’t show up this time. So I ran a faster more aggressive fall curve with only 1000 points and 5 seconds between each point change from 20VDC to 5VDC over a few hours capturing a little over 2000 logs. And again I didn’t see it.
I could run another 19 hour test with 50K logs captured, but this is such a long test to do and not fun to watch  :popcorn: It must be a very specific chain of events that happens to cause this loop.
I think having three different meters see the issue is enough for me. My power supply is needed for some other projects.

I hope all goes well and you have a fast recovery.
Scott

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Offline EEVblog

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Re: EEVblog 121GW Multimeter Issues
« Reply #1076 on: December 05, 2019, 08:17:27 am »
The weird thing is trying to make it repeatable. I did capture another 44K logs and it didn’t show up this time. So I ran a faster more aggressive fall curve with only 1000 points and 5 seconds between each point change from 20VDC to 5VDC over a few hours capturing a little over 2000 logs. And again I didn’t see it.

I doubt it's go anything to do with the input signal, I suspect that's a red herring.
 
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Offline Brumby

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Re: EEVblog 121GW Multimeter Issues
« Reply #1077 on: December 05, 2019, 08:56:46 am »
This has the earmarks of an intermittent.  Whether it's hardware, software or a combination of both is the question - and the answer could be a very obscure set of conditions.

I doubt it's go anything to do with the input signal, I suspect that's a red herring.
I tend to agree.
 

Offline ggchab

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Re: EEVblog 121GW Multimeter Issues
« Reply #1078 on: December 05, 2019, 11:23:24 am »
A guess:  an SDcard write operation takes longer than expected (as others said) --> a write pointer to the buffer is not reset on time for the next value update --> buffer overflow... :(
The SD card write function probably still points the correct buffer but its content is no longer updated because new values are written somewhere (??) else ...
This type of problem might have other side effects ...
 

Offline joeqsmith

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Re: EEVblog 121GW Multimeter Issues
« Reply #1079 on: December 05, 2019, 01:32:31 pm »
The weird thing is trying to make it repeatable. I did capture another 44K logs and it didn’t show up this time. So I ran a faster more aggressive fall curve with only 1000 points and 5 seconds between each point change from 20VDC to 5VDC over a few hours capturing a little over 2000 logs. And again I didn’t see it.
I could run another 19 hour test with 50K logs captured, but this is such a long test to do and not fun to watch  :popcorn: It must be a very specific chain of events that happens to cause this loop.

I think having three different meters see the issue is enough for me. My power supply is needed for some other projects.

Most of the logging I have done is < 5V and < 3000 samples.  Early on, I could not log for very long without problems.   It did not matter how fast I collected the data.   The symptom was the same in that there was no indication that anything had gone wrong until I looked at the data on the card.  It's possible whatever changes were made to improve the reliability of the logging provides a clue to what is still wrong.   

When I first started testing the 1.0 and newer firmware, I had ran a few tests overnight using the function generator to inject a sinewave.   Looking at the data, this was <1V.  I also tried some extended logging at <100mVDC to look at the drift.   As I said, everything has been working and I did a fair amount of logging with the SD card. 

I am running one last test at 4sps with the 50V range, same 2.02 firmware.   I'll again let it capture at least 50,000 samples. 
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline joeqsmith

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Re: EEVblog 121GW Multimeter Issues
« Reply #1080 on: December 05, 2019, 06:39:01 pm »
I had changed three things.  The sample rate went from 0.5sps to 4sps.  I started off with 11.3V, just below where npelov saw it hang.  Changed the load to discharge the battery faster to to compensate for the higher sample rate.   I collected 86,500 samples with no faults.   

I then attached an RC to the meter, trimmed the R to give me a fairly fast decay that I could run in minutes rather than several hours.   I charged the C to 24V, started the 121 logging, still at 4sps and 2.02 firmware.   This time I watched the meter for a while as it discharged.   The sample counter froze at about 180 samples into the run for several seconds, recovered and began incrementing again.       I thought for sure this is what the problem was, so I let it sample about 1000 more and pulled the data. 

We can see it clearly hung.  I am not sure if it's related.     
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 
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Offline joeqsmith

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Re: EEVblog 121GW Multimeter Issues
« Reply #1081 on: December 05, 2019, 11:47:03 pm »
Once again, collecting roughly 86,000 samples at 4sps, 2.02 firmware.  This is with the RC, charged to 24V.  Notice there was a single dropout at sample 14572.  We can once again see at roughly 60,000 samples it hangs again with a repeating sample.
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Offline joeqsmith

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Re: EEVblog 121GW Multimeter Issues
« Reply #1082 on: December 06, 2019, 04:09:14 am »
Applying +/-500mV sine at 10mHz, for 65000 samples recorded at 4sps did not cause produce the repeating hang.   The meter does stall from time to time but it always seems to recover.     I will let it log even longer with the lower voltage level.   So far it appears the only time it has faulted out in this manner is with the higher range.   
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Offline joeqsmith

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Re: EEVblog 121GW Multimeter Issues
« Reply #1083 on: December 06, 2019, 01:16:46 pm »
Scott, read your note.  Hopefully the following will make things a little more clear.    After logging  150,000 samples using the same +/-500mV sine at 10mHz, recorded at 4sps, I was finally able to replicate the problem with firmware 2.02. 

SDLOG9 shows the entire data set.  We can clearly the 121GW get into the repeating mode around 70,000 samples into the run.

SDLOG10 is basically running the data through a highpass to show locations where the 121GW stalled during the collection.   Each peak is a discontinuity in the dataset. It happens a lot at 4sps.   I've known about this problem and have been able to ignore it for the most part.  Having the 4sps has been helpful when looking at how the 121GW's filters respond and I would hate to see them remove support because the meter can't keep up.     Obviously once the fault occurs and 121GW starts recording a repeating pattern, we no longer see the 121GW stall. 

SDLOG11 is zoomed into the area where the fault first occurs. 


I doubt it's go anything to do with the input signal, I suspect that's a red herring.


The problem is not range, level, or shape dependent.   While it does appear to be related to voltage levels, there may be one other variable at play that I had not considered.   When I first started testing, I would erase the SD card prior to running a test.   I then stopped doing this and it appears that as more data is stored on the SD card, the longer it is taking to replicate the problem. 

If we had the source code, we could possible address the problem for you but I'm not sure what more the community has to offer you or UEi as far as tracking down the root cause or this particular issue.

Again, thanks to NPELOV for pointing out this problem.   You may have saved a lot of people wasting their time trying to use the SD card for logging.   
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 
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Offline Scottjd

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Re: EEVblog 121GW Multimeter Issues
« Reply #1084 on: December 06, 2019, 04:12:40 pm »
I did decide to start some more tests yesterday, I wasn't comfortable with only seeing this issue on an older firmware.

Meter 1 on w/FW2.02 on PSU Channel 1 running a faster step down timer compared to my original test. It’s 31VDC to 6.3VDC with 2048 points stepping down every 5 seconds. Since this will not be a long run I decided to cycle repeat this 10 times. This has 3 more cycles before it completes and is still running.
Results:
This one did not have any issues running all 10 cycles.

Meter 2 w/FW 2.02 on PSU Channel 2 is running the original timer when I saw this bug on FW 1.22 in my first tested. It’s the exp. fall slope with 2048 points stepping down every 34 seconds set to run only one cycle. Voltage start at 20VDC ending at 10.8VDC.
Results:
Meter 2 did replicate the issue again starting on log 481 as the first repeated data and continued to the end at log 35447.
I have attached a shortened version of the log.

Information on both meters during the test:
Firmware 2.02
Stock provided 8GB MicroSD card
BT Off, logging to MicroSD card only
Meters interval log capture (In) set for 2
Auto Power Off (APO) is disabled
Current time and date set for time zone EDT
Backlight turned off
Average temperature in the LAB is 21C (70F)
Shielded cables used during these tests

Random information probably not relevant:
Meter 1 Battery Level 5.6V using alkaline cells
Meter 2 Battery Level 4.9V using Eneloop Rechargeable Cells
« Last Edit: December 07, 2019, 05:54:13 am by Scottjd »
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Offline Brumby

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Re: EEVblog 121GW Multimeter Issues
« Reply #1085 on: December 07, 2019, 02:41:39 am »
It is good to see some concerted focus on checking this issue out.  Getting reproducible failure modes with detailed and accurate reporting of such issues will be invaluable in isolating the problem, developing a solution and - one might say even more important - the means to confirm the problem has been properly fixed!

All credit to everyone who takes the time to acquire and share the data.  The more information collected - and the more care taken in collecting it - the more confident we can be of the solution when it is presented.


Pity the source code of the firmware isn't available - but that is understandable because of the proprietary nature of key parts of it.
 

Offline dcac

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Re: EEVblog 121GW Multimeter Issues
« Reply #1086 on: December 07, 2019, 01:49:21 pm »
A while back Dave posted this in the other thread:

For those interested, we (Kane & EEVblog) are now setting up a shared git (not public) for firmware version control with the intention that we (EEVblog) now have full visibility on all firmware changes, and in time will be able to make our own changes and compile ourselves etc.
At present we have almost no real visibility into their internal firmware environment.


But then nothing seemed to happen, or did I simply miss something?

 

Offline emece67

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Re: EEVblog 121GW Multimeter Issues
« Reply #1087 on: December 07, 2019, 02:40:00 pm »
Hi,

Worried about this log issue I started to make my own measurements. The first one was logging the current thru a 2k2 resistor feed by a Li/SOCl2 cell during 24 h at 1 sps, BT off, FW2.00. Nothing to report, all went OK.

The next was a 24 h (in fact ~26 h) log of the mains (230 V/50 Hz here) voltage at 1 sps, BT off, FW2.02. This time the issue surfaced in less than 2 hours:


Zooming into, the first offending sample (5101) is located:



From that point, the same waveform repeats with a period of 60 samples:


I'll try to continue testing other magnitudes.

Hope this helps. Regards.


« Last Edit: December 07, 2019, 02:49:37 pm by emece67 »
Information must flow.
 
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Offline joeqsmith

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Re: EEVblog 121GW Multimeter Issues
« Reply #1088 on: December 07, 2019, 05:15:03 pm »
Hi,

Worried about this log issue I started to make my own measurements. The first one was logging the current thru a 2k2 resistor feed by a Li/SOCl2 cell during 24 h at 1 sps, BT off, FW2.00. Nothing to report, all went OK.

The next was a 24 h (in fact ~26 h) log of the mains (230 V/50 Hz here) voltage at 1 sps, BT off, FW2.02. This time the issue surfaced in less than 2 hours:
....

I'll try to continue testing other magnitudes.

Hope this helps. Regards.

Thanks for taking the time to repeat this test.   As more tests are ran, it does appear to be related to the level applied.  Are both you and Scott erasing the SD card between tests? 
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline emece67

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Re: EEVblog 121GW Multimeter Issues
« Reply #1089 on: December 07, 2019, 05:17:38 pm »
Are both you and Scott erasing the SD card between tests?

Not in my case.
Information must flow.
 

Offline Scottjd

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Re: EEVblog 121GW Multimeter Issues
« Reply #1090 on: December 07, 2019, 08:51:06 pm »
Are both you and Scott erasing the SD card between tests?
I’m not, after all a 12hr to 16hr test only produces a 1mg , to 1.5mg file on an 8GB card.
I also keep known “OK” firmware’s on the SD card. They are renamed as EEVBlog-X_XX
And then I have the backup configuration also on the SD card.
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Offline jchw4

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Re: EEVblog 121GW Multimeter Issues
« Reply #1091 on: December 08, 2019, 06:30:29 am »
Upd: I put thumbnails inline, and the full size images are attached. These are probably too wide to be inlined. So please scroll to the end for full-size images.

I also was not able to reproduce this in the 1V range or with fast changing signal.
But it easily happens in the "battery voltage monitoring", which is basically 1-1/X .
I set up my signal generator like this:


Set logging with 0 interval and left it on for 16 hours:

I did check that the LCD still showed full cycle before I turned it off to extract SD card.

But there is something more. File is corrupted in several places.
Let's check the string length in the file:

Code: [Select]
$ awk '{print length}' 19120701.CSV | uniq -c
      1 27
      1 14
      1 18
      1 32
      1 60
      9 24
     90 25
    900 26
   9000 27
  11476 28
      1 173
  78518 28
  18848 29
      1 419
  17752 29
      1 239
   2927 29
      1 389
  44207 29
      1 389
  20757 29
      1 89
  87220 29
      1 25
      1 21
$


So there is header (first 5 lines of length 27, 14, 18, 32 and 60 characters).
Then there are 9, 90, 900, 9000 lines with increasing index.
But then after 9+90+900+9000+11476 = 21475 lines appears line of 173 characters. What are these?

All the bad lines were longer than 29 characters.
Code: [Select]
$ awk 'length > 30 { print }' 19120701.CSV
,MAIN,,,SUB-1,,,SUB-2,,,Remark,
No. ,Func. ,Value,Unit,Func. ,Value,Unit,Func. ,Value,Unit,
21476,DCV,009.121481,DCV,009.185,V,,,,,,,,
118118861,DCV,009.120,V,,,,,,,,
136614,DCV,009.136621,DCV,009.120,V,,,,,,,,
139561,DCV,009.120,V,,,,,,,,
183769,DCV,009.160,V,183781,DCV,009.120,V,,,,,,,,
204539,DCV,009.166,V,,,,,204541,DCV,009.120,V,,,,,,,,
$

That's interesting, but where are the 173 and 419 characters? Here they are:
Code: [Select]
$ awk 'length > 30 { print }' 19120701.CSV | xxd
00000050: 2c56 616c 7565 2c55 6e69 742c 0d0a 3231  ,Value,Unit,..21
00000060: 3437 362c 4443 562c 3030 392e 3100 0000  476,DCV,009.1...
00000070: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000080: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000090: 0000 0000 0000 0000 0000 0000 0000 0000  ................
000000a0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
000000b0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
000000c0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
000000d0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
000000e0: 0000 0000 0000 0000 0000 0000 0000 0032  ...............2
000000f0: 3134 3831 2c44 4356 2c30 3039 2e31 3835  1481,DCV,009.185
00000100: 2c56 2c2c 2c2c 2c2c 2c2c 0d0a 3131 3800  ,V,,,,,,,,..118.
00000110: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000120: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000130: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000140: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000150: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000160: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000170: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000180: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000190: 0000 0000 0000 0000 0000 0000 0000 0000  ................
000001a0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
000001b0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
000001c0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
000001d0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
000001e0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
000001f0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000200: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000210: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000220: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000230: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000240: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000250: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000260: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000270: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000280: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000290: 0000 3131 3838 3631 2c44 4356 2c30 3039  ..118861,DCV,009
000002a0: 2e31 3230 2c56 2c2c 2c2c 2c2c 2c2c 0d0a  .120,V,,,,,,,,..
000002b0: 3133 3636 3134 2c44 4356 2c30 3039 2e00  136614,DCV,009..
000002c0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
000002d0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
000002e0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
000002f0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000300: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000310: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000320: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000330: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000340: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000350: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000360: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000370: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000380: 0000 3133 3636 3231 2c44 4356 2c30 3039  ..136621,DCV,009
00000390: 2e31 3230 2c56 2c2c 2c2c 2c2c 2c2c 0d0a  .120,V,,,,,,,,..
000003a0: 3133 3935 3439 2c44 4356 2c30 3039 2e31  139549,DCV,009.1
000003b0: 3630 2c56 2c2c 2c2c 2c2c 2c2c 0d00 0000  60,V,,,,,,,,....
000003c0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
000003d0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
000003e0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
000003f0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000400: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000410: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000420: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000430: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000440: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000450: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000460: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000470: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000480: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000490: 0000 0000 0000 0000 0000 0000 0000 0000  ................
000004a0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
000004b0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
000004c0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
000004d0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
000004e0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
000004f0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000500: 0000 0000 0000 0000 3133 3935 3631 2c44  ........139561,D
00000510: 4356 2c30 3039 2e31 3230 2c56 2c2c 2c2c  CV,009.120,V,,,,
00000520: 2c2c 2c2c 0d0a 3138 3337 3639 2c44 4356  ,,,,..183769,DCV
00000530: 2c30 3039 2e31 3630 2c56 2c00 0000 0000  ,009.160,V,.....
00000540: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000550: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000560: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000570: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000580: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000590: 0000 0000 0000 0000 0000 0000 0000 0000  ................
000005a0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
000005b0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
000005c0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
000005d0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
000005e0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
000005f0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000600: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000610: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000620: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000630: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000640: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000650: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000660: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000670: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000680: 0000 0000 0000 0000 0000 0000 0000 3138  ..............18
00000690: 3337 3831 2c44 4356 2c30 3039 2e31 3230  3781,DCV,009.120
000006a0: 2c56 2c2c 2c2c 2c2c 2c2c 0d0a 3230 3435  ,V,,,,,,,,..2045
000006b0: 3339 2c44 4356 2c30 3039 2e31 3636 2c56  39,DCV,009.166,V
000006c0: 2c2c 2c2c 2c00 0000 0000 0000 0000 0000  ,,,,,...........
000006d0: 0000 0000 0000 0000 0000 0000 0000 0000  ................
000006e0: 0000 0000 0000 0000 3230 3435 3431 2c44  ........204541,D
000006f0: 4356 2c30 3039 2e31 3230 2c56 2c2c 2c2c  CV,009.120,V,,,,
00000700: 2c2c 2c2c 0d0a                           ,,,,..
$


So basically there are random blocks of zeroes and some lost data.

Do these correlate with the output problems?
I replaced corrupted lines with impossible value of -1V:


Here is magnified graph just before it stopped:

(it is attached to the next message.)

I am also attaching the original file (to the next message) if you want to play with it yourself.
« Last Edit: December 08, 2019, 12:36:11 pm by jchw4 »
 

Offline jchw4

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Re: EEVblog 121GW Multimeter Issues
« Reply #1092 on: December 08, 2019, 06:32:47 am »
I expected all the images to be inlined, but it did not work. ;(
And file 19120701.CSV.7z failed to upload (or maybe it is only visible to moderators?).

How do I insert attached images inline?
upd: I followed jancumps advice below.

The missing files are here.
« Last Edit: December 08, 2019, 12:37:58 pm by jchw4 »
 

Offline jancumps

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Re: EEVblog 121GW Multimeter Issues
« Reply #1093 on: December 08, 2019, 08:35:55 am »
save your blog with the images attached. Then copy those images hyperlinks (in most browsers right-click then copy link).
Edit your post again.
Navigate to where yoy want your image.

Press the Image button above the editor.
Put the url between the two image tags that just appeared.
« Last Edit: December 08, 2019, 08:37:40 am by jancumps »
 
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Offline jchw4

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Re: EEVblog 121GW Multimeter Issues
« Reply #1094 on: December 08, 2019, 01:05:39 pm »
Combining different posts, probably the key to reproducing "4 values" issue is to use > 5V voltage range.
Could somebody reproduce it with 500mV and 50mV ranges?

Upd: https://www.eevblog.com/forum/testgear/eevblog-121gw-multimeter-issues/msg2817450/#msg2817450 500mV seems to be affected too.
« Last Edit: December 08, 2019, 01:09:00 pm by jchw4 »
 

Offline EEVblog

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Re: EEVblog 121GW Multimeter Issues
« Reply #1095 on: December 09, 2019, 01:56:37 am »
I finally got it to fail, same conditions as before, 5V range. Seems quite random whether it happens or not, I have not been able to get it to happen again yet, but once is enough of course. Same SD card, not erased. 2nd image is just zoomed in around the 10,000 sample mark from the first image.



 
The following users thanked this post: Scottjd, AlanS

Offline ggchab

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Re: EEVblog 121GW Multimeter Issues
« Reply #1096 on: December 09, 2019, 07:26:10 am »
 

Offline emece67

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Re: EEVblog 121GW Multimeter Issues
« Reply #1097 on: December 14, 2019, 09:17:44 pm »
Hi,

This time the bug showed when measuring resistance. After a 7 hours logging of the resistance of an LDR, it started to cycle at about 3.5 hours. As before, the cycle lasts for 60 samples (FW2.02, BT off, 1 SPS, Ohm).







Regards.
« Last Edit: December 14, 2019, 09:23:14 pm by emece67 »
Information must flow.
 

Offline 1anX

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Re: EEVblog 121GW Multimeter Issues
« Reply #1098 on: December 15, 2019, 12:32:05 am »
Joe Smith has his final 121GW video out and he notices in his switch test and evaluation that Dave in his EEVBlog video shows the spacer being inserted upside down?

Just a heads up to anyone who received a separate spacer and self installed it to double check which way it is installed, (Dave may wish to comment on which way is correct?). The switch spacer insertion is shown around the 39.00 minute mark in the video.

The switch wear and final summation of the 121GW as viable meter for your money by Joe is pretty much to the point (as always) so I recommend watching this video before purchasing the meter.





 

Offline Stonewatch

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Re: EEVblog 121GW Multimeter Issues
« Reply #1099 on: December 15, 2019, 07:35:48 am »
SW version 2.02.
Measuring the output voltage of a VFD yields wrong results both frequency and voltage.

 Using the 1kHz filter makes matters even worse.

The BM 869S, BM235 or the Fluke 28II  have no problems with these kind of signals, whereas  the BM27s goes crazy.


Another issue remains autorange with capacitors
« Last Edit: December 15, 2019, 06:50:39 pm by Stonewatch »
 


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