Thanks for the kind comments.
Also, the meters handled the 3 floor drop test better than I thought they would have. Did any come out without damage outside of scuffs/scratches/cracks?
It would be very hard to say just how much damage was done during drop as the meters had all been pretty much destroyed beyond repair by this stage of testing. There was one meter that it tore an IC off the board during drop. Many of the LCDs were damaged. That Circuit-Test was the only somewhat working meter I dropped. It cracked the kickstand in half but really that meter held up very well which was why I gave it its own little segment. I really thought the the INNOVA would do nothing in the drop because it is so light but that was not the case.
I might have to get me a Fluke 107...
5ky has offered to allow me to continue to test the Fluke 107. Don't be too surprised to see in a later video. The things I did not like about the 101, like the ultra slow continuity test, lack of a backlit LCD were addressed, plus you can measure AC and DC currents. Still not a very feature rich meter but hard to argue how electrically robust it is.
After all this, I am now interested in how the Flukes were designed so that they survive the 12kV pulse.
I don't think the secret is in the schematic.
A lot of the meters have the same level of protection but the MOVs and PTCs blew apart. The ones inside the Fluke didn't. Higher quality/better rated components in the Flukes...?
Exactly, I wonder what happens to the various MOVs PTCs ect when fed 12kV. It may be a simple gross overload, or possibly something more sinister such as leakage like non ideal behaviour that permits overload into sensitive areas.
It's time for me to learn about MOVs and the other protection device's real properties.
Take it for what its worth, I have now put 23 meters to the recycle bins. It's not a lot of data but worth a high level rundown of the types of failures I have seen from running these tests.
I would say the highest failures that cause the meters to be non-repairable, the control IC is damaged. This happens a lot. To be clear, I am not at all suggesting that the IC is the problem with the designs where they fail.
Transistors/diodes. This is been a very common theme. In these cases, most appear to be setup as a clamp. In many cases, these parts will blow apart and become an open. Then the transient will continue to the next part. Normally the control IC. In most cases where the IC was damaged, a clamp was damaged too. Most, but not all. In some rare cases I suspect the IC was damaged with no other damaged parts.
PTCs have taken their fair amount of damage. I most cases, they still work even though they arc over. The arc will often damage the outside coating assuming it has one. Parts that do not have this layer just arc around the outside. Of course, this nice low impedance arc will go to the next thing down the chain, normally the clamp. In some rare cases the PTCs were damaged beyond the point where they would function.
MOVs Well, my own experience with MOVs is they degrade and short. Their cases will catch fire and crack. For the meter's I have damaged, I have never seen an MOV fail. This does not surprise me at all nor should it surprise anyone here. The MOVs used are normally behind a PTC and are going to handle a fair amount of energy. Again, the amount of energy I am using to test these meters is VERY small. Enough hits' I would expect to see them degrade. This again is why I get confused when people talk about correlating these tests with meter safety. That's just stupid. There just is not enough stored energy to do anything like explode a meter. And again, that was never a goal of mine.... Sorry for beating the dead horse, yet again....
Resistors I was going to post HV resistors but that may confuse a few people. In several cases, I have seen the front end built with 1206s and other small packages. Some meters will use little MF 1/4 axial parts. This is not always a problem but there was a meter in this last set of tests that used 1 pc of a 1/4 MF resistor in series with a PTC then to a MOV.
Worse, I think that meter had footprints for some HV parts!! Again, everyone wanting to make their profits. Like the Brymen, this particular meter had two different circuits, each with their own single 1/4 MF resistor, going to the Vin jack. Both of those resistors opened up.
Circuit boards There are two things I see happen. Traces will not handle the surge and become damaged. In some cases, this has caused even more damage to other circuits once they open up. The other problem has been lack of creepage distance.
Other Let's stop using lead in solder again
Here's an idea, make reliable products that don't end up in land fills! I have seen more than one solder joint fracture. Some are just poor hand soldering. Normally, problems like this I just fix and move on with the testing. That said, most of these are now lead free and look good. Time will tell how this plays out.
So I stated in the video that I thought it would not take a whole lot to get the Brymen to pass that last test. While the Brymen BM869s was damaged, the two transistors still sort of worked. In most cases, when the diodes or transistors like this have failed, there was enough going through them to make the damage very visible.
Take that Danaher 87V for example. Three diodes damaged and the transient cracked every case. As you saw from my video, that Brymen can read in the pf. So shoving a MOV across the input with 2000pf may not be such a smart idea but in some cases this may not be critical. I don't think you will find a single one size fits all fix.
If we wanted to talk about safety, I think you need to consider that in some cases what I wrote about the failures may have been by design to prevent a hazard. Take for example the meter that I mentioned from 5ky that had the two 1/4W MF parts. Sure I bitched about the pads allowing for a larger package. However, that fact that they opened my have been by design to prevent a hazard.
I don't know, nor do I care as I have no interest in using a meter like this in a high voltage high energy applications. I am interested in a meter that is robust as well as feature rich. The Brymen BM869s is the best I have seen for my use.
Sorry for the long post. Hope it helps tie things together.
You seem full of praise for the Brymen and scorn for the Fluke 87V.
If I understand correctly, they both failed at 13kV on the Ohms range only and were both fixed by replacing a couple of transistors.
Can you explain the reason for the dichotomy?
Yes, I was wondering too.
Fluke, what can I say that has not already been written in the history of Fluke and Danaher.
"At Danaher, our vision is that associates and customers will demonstrate extraordinary loyalty; that we will be respected and admired by all who come into contact with us;...."
I admire the way the $400+ 87V is tested in your labs but blew the backs off of three diodes during a test that your $50 meter withstood! A $50 meter that you do not even mention on your US website nor offer in the US. Good Job Danaher, you have my respect!! And really, isn't the fact that I have taken the opportunity to post videos about my very first digital meter that I have kept over three decades, demonstrate my extraordinary loyalty to the brand? You have placed yourself on a pedestal for all to admire.
Brymen, what can I say. I am impressed with your website!
I know you wrote that the BM869s would not survive my 6KV hit by design, but you were willing to back me up and push ahead. When the BM869s was damaged, did you back out knowing very well I had just hit the meter with far more than it was ever designed to handle? No, you held up your end. And when I offered to have a look at the meter to see what had happened, did you say that would void the deal. No, you hung right in there. That is trust! You are an engineering company for engineers not some princess on a pedestal! I have no doubt reading the history of your company where you are heading.
If I wanted to buy a Danaher/Tektronix scope to put on a pedestal I would but I am surrounded by old LeCroy scopes for a reason!
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