Handheld meter robustness testing

[joeqsmith]

Both 97s are in pretty rough shape.  Shown before and after just using the rubbing compound.  It's better but I think it's time to try something a little more aggressive.. 

[joeqsmith]

Belkin iPad screen protector.  $5 for a fairly large amount of material.  Does not seem to impede the viewing and should protect the 181A's lens from further damage.   Pretty happy with the end results. 

[bitseeker]

Nicely done, Joe. I see you got a score on that screen protector. I can imagine an iPad-sized sheet goes a long way for handheld DMMs.

[Muttley Snickers]

I hate scratches with a passion and as you have done I put screen protectors on everything, I don't see any point spending hours buffing scratches out of a screen and then not taking additional steps or precautions to help minimise them occurring again in the future.   

Nice work as always Joe.   

[stj]

it's too bad the chinese dont sell toughened glass shields, like they do for phones.

[joeqsmith]

I ended up getting two of these packets.  Each packet comes with two sheets.  With one sheet, I also covered the Fluke 189, my Brymen and Dave's 121GW.  There's still a bit left.   The product is fairly easy to work with.   I give it and the PlastX both the   

[stj]

what is it, mylar?

[joeqsmith]

what is it, mylar?

Sorry, I would have no way of knowing what they are using.  It's not on the package.  Maybe their website has more information about it. 

Nope:
http://www.belkin.com/us/p/P-F8W526-3/

[joeqsmith]

I am now the owner of a Fluke 189.  Don't look for it on the transient generator any time soon.   If I could buy a brand new one of these, I would run it.   

Some time back I ran an AN8002.  It held up better than a lot of meters, has more features than the Fluke 101 and is about  the same size.  The meter was badly damaged but I have ordered a brand new one.  My intent is to see if I can fit a few MOVs inside it and further increase it's robustness and maybe make a few other mods to the hardware. 

Also, I have the AN8008 on order to do a side by side comparison of the layout and run some ESD tests on.  Maybe the new ESD gun will finally damage a meter, proving that it actually does anything.

[floobydust]

That 189 looks pretty good after the cleanup. It's worth it. I got a free multimeter with crude oil all over it, that was fun cleaning.
Used every household cleaner I have first, like IPA, Fantastic, dish soap etc. and then Comet (abrasive cleaner) and a scrub brush as the last step. Toothpaste scrub on the display window.

I haven't looked for the AN8008 PTC, it seems to be an Epcos part and DMM app notes say it affects measurements with big 10mF capacitors, so want <2k\$\Omega\$
If it turns out the PCB traces are the limiting factor, conformal coating in spots is the only fix I know of. I think the rotary switch is the bottleneck.

[bitseeker]

Wow, that 189 sure cleaned up well. I wouldn't have expected it from such a light-colored holster.

[joeqsmith]

I was very much surprised when he offered it to me.  This was a dish soap and hot water job.  The meter has some marks on it from the previous two owners that I did not want to remove.  It's seen a lot of use in the automotive world.  The plastic is in fair condition.       

The AN8002's PTC's logo is similar to Epcos but I don't think it was made by them. 

Most meters I have looked at all have similar designs to protect the sensitive parts.  Really, IMO there is absolutely no reason why any meter would not be designed to handle the basic transients I put them through with my little generator.  This is IMO especially true when you start looking at $100 and up class meters. 

Now if the companies just started to design them to be connected to the outputs of MOT and car ignition coils, we would see a lot less failures...

[floobydust]

A very long time ago, I was at Radio Shack and a guy's wanting a refund for his Micronta analog multimeter.
It had literally exploded, the range switch blown out.
The guy had put it on amps, stuck the probes in an outlet to see if he was getting 15A like the breaker's rating 
Store manager gave him a full refund, and almost kicked me out of the store for mumbling 'WTF did he do?!'

I wondered the voltage rating on the PTC "03M" seems to be Apr MZ31 series. Epcos PTC's are all blue, B59886C012 is a 500V 12mA part.

Other meters use a GDT but I think these are slow to ionize, and compared to your impulse generator, MOV's maybe fast enough.

[totalnoob]

Well, did he get all 15 amps?     

[Fungus]

Well, did he get all 15 amps?     

Sound to me like he did.

[floobydust]

In those days, cars had no airbags, no helmet to ride a bicycle, and multimeters had no fuses: Micronta_22-204A

[bitseeker]

All multimeters have fuses. The properly designed meters have intentionally placed ones. The rest are random.

[Muttley Snickers]

All multimeters have fuses. The properly designed meters have intentionally placed ones. The rest are random.

I regards to the major current input my Metex M-3650CR doesn't and neither did the Fluke 75 similar to the one pictured below which exploded in my left hand after a silly mistake involving three phase, it went off like a bomb, seriously.   

[bitseeker]

Woah! Hope your hand was OK.

[tautech]

Woah! Hope your hand paw was OK.

[Muttley Snickers]

They had proper thick holsters back then which managed to contain most of the blast, the selector switch and the screen acrylic went west and I ducked to the east, it's funny reading other peoples comments or theories on what may or may not happen during an event such as I described, until you have been there first hand everything else is just speculation.

[joeqsmith]

They had proper thick holsters back then which managed to contain most of the blast, the selector switch and the screen acrylic went west and I ducked to the east, it's funny reading other peoples comments or theories on what may or may not happen during an event such as I described, until you have been there first hand everything else is just speculation.

So just to be clear, are you promoting cheap crap handheld meters and your favorite brand is UNI-T??        

I wondered the voltage rating on the PTC "03M" seems to be Apr MZ31 series. Epcos PTC's are all blue, B59886C012 is a 500V 12mA part.

Other meters use a GDT but I think these are slow to ionize, and compared to your impulse generator, MOV's maybe fast enough.

This looks more like the logo.  I could believe the 500V rating.   They won't normally have a pulse rating on them.   A lot of companies put these piss ant PTCs in there.  They don't normally do well with my tests.   Again, really no excuse to make a meter that is not fairly robust now days.  It's not the 1980s.  Parts are readily available and the basic techniques on how to protect them is not some major PHD project.

Yes GDTs are slower than MOVs to turn on.  I made a video on switch time comparison and basic frontend protection. GDTs also latch as basically a dead short.  I assume the companies the use them do not consider the DC mode being a high risk or they have a MOV for the reset.   Very rare I see them used in handhelds. 

I looked at three meters that used GDTs.  I don't see a problem using them for the first stage of clamp assuming the designers did their job.  Of the three I tested, HIOKI, Gossen and Keysight, the Keysight was damaged at a fairly low level.   This is the reason you don't ever see a high end Keysight meter here.   Gossen has other issues. 

[Fungus]

I just noticed you never measured the Fluke 87V continuity tester speed. I wonder if it would beat your Brymen.

[kalel]

Speaking of continuity, as I never owned an "expensive" (I know that's relative to people and purpose) meter myself, how do the DT830's stack up with the higher quality meters?

[Fungus]

Speaking of continuity, as I never owned an "expensive" (I know that's relative to people and purpose) meter myself, how do the DT830's stack up with the higher quality meters?

You mean the freebies? They measure OK but they're liable to fail at any moment and I wouldn't put them within 10 yards of a mains socket.



Do they even have a continuity test? Mine doesn't.