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What are - for you - the 3 biggest disadvantages of your benchtop DMM(s)?
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Rasterist:
Keysight 34461A:  takes too long to boot up.  Especially annoying since it's never completely off; there's an LED on the front indicating it's only asleep.  Nevertheless, it's 29 seconds from hitting the power button until being able to make a measurement.  For this reason, I always reach for my Fluke 87V unless I need the precision or some other unique feature of the 34461A.
floobydust:

--- Quote from: bdunham7 on September 02, 2020, 09:39:11 pm ---
--- Quote from: floobydust on September 02, 2020, 07:13:06 pm ---I frequently go near or over 750-1000V,

--- End quote ---

You might want to rethink routinely running near-limit voltage through your very best DMM (if that's the case)...
--- End quote ---

I understand benchtop DMM's are fragile. Cat. II 300V is 2,500V/12R impulse. Will a BBQ lighter kill it? These kinds of small transients (not mains spikes) are commonplace to a multimeter when doing SMPS work for example. You get a fast dV/dt and it's a little hit. I don't want to find out the hard way the benchtop DMM is too fragile for practical use.
I've also made test benches for products using benchtop DMM's and a mux for bed-of-nails automated testing. Sometimes there is a failure (connection, pogo-pin, software etc.) and the DMM gets overloaded. I think it's a reasonable use-case. I see a couple MOV's, couple gas-tubes but no PTC in common benchtop DMM pics. Their relays are like 1,000V or 1,500V isolation. They have weaker front-end protection and questionable transient testing 61010 certificates.

"Keithley products are designed for use with electrical signals that are measurement, control, and data I/O connections, with low transient overvoltages, and must not be directly connected to mains voltage or to voltage sources with high transient overvoltages. Measurement Category II (as referenced in IEC 60664) connections require protection for high transient overvoltages often associated with local AC mains connections. Certain Keithley measuring instruments may be connected to mains. These instruments will be marked as category II or higher."
0culus:

--- Quote from: bdunham7 on September 03, 2020, 03:07:09 am ---
--- Quote from: joeqsmith on September 03, 2020, 02:51:45 am ---If it was exposed to an event that required repairs, it didn't survive.  Rather I would say it was repairable or salvaged.

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OK, fair enough.  I did say it was a debatable point.  Would you say the same for a meter that required the replacement of an internal fuse after exposure to excess current?  If not, then why would you have a different opinion when the items that 'failed' (actually they worked) are protective devices specifically intended for this purpose?  Of course, I'll grant that the MOVs might not fall into the same category as the fusible resistors, incineration isn't their normal mode of operation.  :o

My gripe here isn't about the definition of 'survived', it is that the aversion to repairability is causing people to completely shun 'repairable' failure modes.  Why have MOV protection when they could fail?  Just let the CPU take the hit--after all dead is dead.  I suppose that's true for cheap consumer products and things we send into space, but I don't think it should be for expensive instruments--at least where it is practical to build them otherwise.

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Lack of repairability is largely pushed by the vendors, and it really started in the 1980s and has only gotten worse. Why? Well, now when you break it out of warranty they can sell you a new one. They all like to maintain their trade secret designs too. 50 years ago this was not the case. Crack open the manual for a Tektronix 500 series oscilloscope...it is plainly obvious that they intended the end user to service their own instrument. They even gave you a roll of silver bearing solder! Then go download a manual for the 24xx series scopes and it's obvious how things had changed even by 1990 or so.  :--

That doesn't mean new stuff is unrepairable; the company just won't help you out at all. You have to reverse engineer it and understand how it works and the failure mode, and maybe have a few special tools. A perfect example of this is the infamous "red ring of death" failure for Microsoft's Xbox 360 game console. Many of them got thrown away, but it's really a failure of the BGA under the CPU, and it can be easily fixed if you have the capability to reflow. Also "The Signal Path" on youtube; his expert knowledge allows him to repair test gear that would otherwise get tossed.

Personally, I don't do very much work around truly high energy stuff (beyond single phase wall voltage), but if I did I certainly would want NEW equipment and not repaired equipment. It's not worth gambling your life when arc flash hazards are involved. For everything else I play with on my bench, repaired old equipment all the way.
joeqsmith:

--- Quote from: floobydust on September 03, 2020, 05:22:24 am ---I understand benchtop DMM's are fragile. Cat. II 300V is 2,500V/12R impulse. Will a BBQ lighter kill it? These kinds of small transients (not mains spikes) are commonplace to a multimeter when doing SMPS work for example. You get a fast dV/dt and it's a little hit. I don't want to find out the hard way the benchtop DMM is too fragile for practical use.
--- End quote ---

I never thought I would see the small lighter I use damage any meter but here we are.  Countless UNI-Ts dead and even the holy grail, the 121 was damaged to where it threw off the measurements a fair amount.   It's hard to believe as that ignitor is so weak.   

While I would assume most people would take steps to reduce ESD in their labs, its the other transients that I am also concerned with.  When I was young, I built a power supply like many beginners.   I then proceeded to hook it to all sorts of things.  One was an electromagnet.  I wasn't educated to know what BEMF was.  40 some odd years later, I have MOVs and TVSs internal to all my supplies.   :-DD  They still are not bullet proof.

Imagine the beginner wanting to measure the resistance change of their large electromagnet.  They attach their meter across the coil, measure the resistance, then power up the coil with their 9V battery, let it heat and then remove the power by disconnecting the leads.  The beginner who swears they never play with HVs has just damaged their new meter.   :-DD   Most of us do dumb things like this at one time or another.  It's how we learn.   

IMO, cheap meters have their place.  But a beginner who buys a meter that can't survive even that stupid grill starter and other basic transients may find themselves buying another meter.   Steering beginners to buy robust meters that may survive all the thing they expose them to, may make learning electronics more enjoyable but stressing about the meter you just blew up because of some stupid mistake is part of it.   I can't see robbing a beginner of that experience..     
SilverSolder:

--- Quote from: bd139 on September 01, 2020, 01:33:53 pm ---3478A:

1. Horridly bad LCD display
2. No continuity / feeper
3. Terrible front panel legend meaning I always stick my probes in the wrong holes.

That’s about it.

--- End quote ---

A DYMO labeler could be your new best friend!  :D
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