Handheld meter robustness testing

[joeqsmith]

Looks like the diode test voltage was lowered.  I lost the CMOS switch twice and had changed the part to higher voltage one and added a TVS to protect it.  Margins were pretty tight but the meter survived after this.  I was hoping they could find a fix as the 15V feature would have been very nice for checking high voltage diodes.

[joeqsmith]

I made a second attempt at modifying the Kasuntest ZT102 to see if I could get it to survive some basic levels from my transient generators.

https://youtu.be/-V9JvFRjL78

[Crumble]

Nice one Joe! This must have been a hell of a lot of work. I actually found this one quite captivating. At one point I stopped it, but changed my mind and watched the entire clip because i was genuinly curious how it would end. Nice to see the meter survives now, did the Hioki not break down in a similar way?

[3db]

14 KV !! Awesome work Joe. 
Very interesting video.
Appreciate the time and effort you give in order to make these videos.

3DB.

[joeqsmith]

Nice one Joe! This must have been a hell of a lot of work. I actually found this one quite captivating. At one point I stopped it, but changed my mind and watched the entire clip because i was genuinly curious how it would end. Nice to see the meter survives now, did the Hioki not break down in a similar way?

Yes the HIOKI I ran broke down because of some plastic that was not quite large enough and the meter was not electrically damaged.   This meter was similar in that it was not damaged. 

14 KV !! Awesome work Joe. 
Very interesting video.
Appreciate the time and effort you give in order to make these videos.

3DB.

Well, a solid 10KV anyway.   You want 14KV, you got it.   This was really the goal, get it up to the levels that the most robust handheld meters I have tested survive at.  There is not a lot of science to it but I hope that it shows that its not something that is all that difficult to achieve.  I really see no reason that especially the $100 and up meters will not survive to the levels this modified $15 Kasuntest meter will.   

https://youtu.be/dEwLuiYX5cQ

[joeqsmith]

Someone had requested the dead meters be drop tested. 

https://youtu.be/PYFs9F0scDQ

[bitseeker]

Joe, you're really widening your equipment-destroying horizons. Break a leg...er...an instrument!

[floobydust]

I worked for a Telecom manufacturer and they did 1m drop testing on hard floors.
Scared the !Q@#%^@#^ out of me, mechanical engineers go in the lab and start throwing them down. SMACK! Buttons flying everywhere.
Results seemed so variable, if the display hit or the buttons hit first. It was a free-fall standard, but they threw them down to find the design weakness.

The main point was the desk phone would not crack or break under a typical slide off your desk scenario.

[Crumble]

A two floor drop and just a few scratches, seems reasonably robust to me. It may be helped by the fact they weigh almost nothing. It does seem that good spring material is difficult to get, i have had issues with fuses not connecting properly in cheap meters.

[joeqsmith]

The three CEM DT9939s. These are 40K count, have an internal RF link and tri-display.  They also have basic features like AC+DC.    A few of us bought the CEM from Ruby Electronics when they were selling them for $120.  I've made a review of them and showed many problems with the meter on the right.   

The meter in the center is from work.  It was just calibrated and turned five years old.  The meter has had a rough life.  I loaned it out once and the person had turned the knob past the dead stop.   A few times it came back with blown fuses.  Then I put it through a fair amount of abuse myself.  People say how they never use their meters about 40 deg C.  This meter has been used above those temps with the RF link.  I've dropped it a few times and you can see how the case has discolored with time from being out in the sun.

We would never have them generate a calibration report for a handheld so I don't have any records on drift.  It has never been aligned and I thought for fun I would compare it against some of my home equipment.   

[bitseeker]

Looking forward to the review, Joe.

[joeqsmith]

Happy Birthday EX540

https://youtu.be/Yih7D23z7vE

[joeqsmith]

I was asked if all I did was add more dope to get the Kasuntest to survive at higher levels without breaking down.  This video shows what it ended up looking like.  More than just dope.   

I also thought I would show how the current measurement compares with two other meters. 

https://youtu.be/EkQ6CCj7jmU

[MacMeter]

AMAZING, originally a $20 meter, guessing after time, parts, and labor, now CUSTOMIZED at over $500!

[Cliff Matthews]

AMAZING, originally a $20 meter, guessing after time, parts, and labor, now CUSTOMIZED at over $500!

The exercise is not to waist time and money (maybe it's pastime with a purpose?). Joe's channel is the only one I know of that stands up to poor DMM manufacturers by sharing what could have been done but wasn't (for a whole host of reasons).

[MacMeter]

AMAZING, originally a $20 meter, guessing after time, parts, and labor, now CUSTOMIZED at over $500!

The exercise is not to waist time and money (maybe it's pastime with a purpose?). Joe's channel is the only one I know of that stands up to poor DMM manufacturers by sharing what could have been done but wasn't (for a whole host of reasons).

You misinterpreted my post, I love the time and effort Joe takes to produce his videos, not sure where he finds the time. My point was there are probably some that would love one of these tiny meters that are customized to such a higher quality degree, but it would cost TOO MUCH in reality. So again, a $20 meter can be "upgraded" to much better grade, but I'm sure Joe would laugh at being able to make any money after his time, labor, and parts, even at $500!

[joeqsmith]

AMAZING, originally a $20 meter, guessing after time, parts, and labor, now CUSTOMIZED at over $500!

The exercise is not to waist time and money (maybe it's pastime with a purpose?). Joe's channel is the only one I know of that stands up to poor DMM manufacturers by sharing what could have been done but wasn't (for a whole host of reasons).

You misinterpreted my post, I love the time and effort Joe takes to produce his videos, not sure where he finds the time. My point was there are probably some that would love one of these tiny meters that are customized to such a higher quality degree, but it would cost TOO MUCH in reality. So again, a $20 meter can be "upgraded" to much better grade, but I'm sure Joe would laugh at being able to make any money after his time, labor, and parts, even at $500!

If you would like a better handheld meter the best option is to just buy one that meets your needs.   If you are interested in seeing a particular product  improved, I would contact the manufacture and let them know what features you are interested in.  I would never suggest anyone attempt to modify their handheld meter like I have shown.  I certainly would never offer any sort of a modified handheld meter or kit for sale.  I would see this as nothing more than a scam.  Worse, you are putting people at risk over a few dollars.  Sorry, not interested.

I did hook up the programmer and downloaded the contents of the PROM for the ZT102.  I went ahead and opened the window for the Amps range so the uA no longer beeps.  I also moved down the warning and over range limits.  I started to look at the switch and it does not seem like there is a clean way to change it. 

This is the unmodified contents:
:10000000FFFFFFFFFFFFFFFFFF5200BE0070C903AD
:100010001017381844026E50644B3C3C0AFF40FFF6
:10002000C798E38264009600008000803B7E826F68
:100030004E020930010A9AF60984F509E8030A001C
:1000400000010001000798006400640064000000E3
:1000500000800080008000800080008000800080A0
:10006000817E00830100922A000000000000000051
:1000700053810080C57DE07C180100000000000075
:100080000000000000001013000E00070012030122
:100090000000000000001115000F0009000004021C
:1000A00000000000000000000000000A0000000046
:1000B00000000000000000000000000B0000000035
:1000C0000D0002100D00032020000320200003106B
:1000D0000080008000800080410003050D000220A8
:1000E0000080008000800080008000800080008010
:1000F0000080FFFFFFFFFFFF5AC7CC0F0FA20000D9
:00000001FF


 

[joeqsmith]

What ever happened with Randomtronics?   I was watching his review of the AN8002 and I am not so sure the RMS conversion is as bad as it was made out to be in the video so I though I would run a quick test of my own to compare the ZT102 with a few meters. 



Randomtronic's video may be found here:
https://youtu.be/oNss6h0Zu98

[MacMeter]

Joe, did you read the first few comments on the YouTube page? There were some that pointed out his little mistake that he then acknowledged. All a bit over my newbie head.

[joeqsmith]

Yes, I read them.  I thought I would try and make it a little clearer. 


Rob C1 month ago

I am still confused by the comments is this meter true RMS or not??

Reply•   

[joeqsmith]

Someone asked about how these changes to the ZT102 effected its frequency response. 

https://youtu.be/0nxjyqJf2jI?t=2

[sleemanj]

What ever happened with Randomtronics? 

I think he must have moved or something and his equipment is still in packing boxes going by recent replies to comments.

[floobydust]

True-RMS (calculation) is AC coupled in the DMM IC used in the AN8002, AN8008 etc.
I thought any DC offset is ignored as part of the calculation.

But some DMM's include the DC portion if using the good old analog AD536 true-RMS converter (which costs much more than a cheap multimeter...)
Joeqsmith, didn't you already try adding a DC offset to a waveform, many posts prior?

[Fungus]

True-RMS (calculation) is AC coupled in the DMM IC used in the AN8002, AN8008 etc.
I thought any DC offset is ignored as part of the calculation.

But some DMM's include the DC portion...

I'd argue that it's more correct to include the DC portion because not all waves are symmetrical.

Where there's a DC offset it might be better to have a vpp function but I don't recall seeing that on a meter.

[floobydust]

I have a DMM with a switch for true-RMS AC+DC, or true-RMS AC only. Basically switches in/out a coupling cap to the true-RMS converter IC.

On the grid, pretty much no DC offset due to transformers. Missing DC is OK there, but not doing measurements on SMPS DC bus etc.

The DMM IC has result registers for DC and AC true-RMS (LPF) so they could be both used but the econo MCU is very basic and can't do math like multiply, square-root etc.