Buying second hand DMM trouble ? - Page 1
Forum section: electronics / testgear

author: JanJansen
author_rank: Frequent Contributor
timestamp: April 27, 2017, 04:10:16 pm
content: Hi, would you buy a second hand DMM ?When is a DMM to old to buy second hand ?Can it have a lot of problems ?, how do i know its good ?What does new DMMs has that old ones dont have ?I better buy a new one to stay out of trouble ?thanks

author: james_s
author_rank: Super Contributor
timestamp: April 27, 2017, 05:57:15 pm
content: Buying anything used is always a bit of a gamble, but personally I've bought all of my test equipment used and almost all of it has either worked perfectly or I knew it was broken when I bought it and I was able to fix it. I would not hesitate to buy a good quality DMM like a Fluke, Tek, Agilent, etc used. They are pretty robust and it's rare that one will be seriously damaged.

author: rsjsouza
author_rank: Super Contributor
timestamp: April 27, 2017, 06:08:10 pm
content: I echo the same comments as james_s. I have purchased a large number of used DMMs from eBay and so far there was nothing I couldn't repair myself.Our own EEVBlog user excavatoree posted a very nice buying guide a few years ago. Check:http://www.ebay.com/gds/Fluke-Meters-Main-Read-First-/10000000007231862/g.htmlIn this case, what exactly are you looking for? Perhaps there is some specific feature or model that we can comment better.

author: Alex P
author_rank: Contributor
timestamp: April 28, 2017, 11:24:38 am
content: Yes, I've bought half a dozen second hand. Try them out, and do check the fuses (people do replace them with aluminum foil or unsafe small fuses). Maybe I was lucky, but all sellers I bought from turned out to be honest. All the six used Fluke 8020 / 806x and newer handheld meters I ever bought were fully functional (except for the display on very old ones - replacement is a nice little exercise), and the limited amount of checks I did (compared to a 6.5 digit meter with valid calibration) showed them to be still in spec. Same for a fairly new used Agilent meter.Then again, someone gave me an old meter of a brand I do not remember. Garbage.Fluke 802x series meters from the 1970s can have a bad display or leaky capacitors, so yes, they can have problems. If you're not knowledgeable about it, only buy from someone you trust.Old ones don't have autoranging, and don't measure capacitors. New ones can draw much battery current (weeks for a set of AAs in a newer meter e.g. Fluke 287 vs. years for a 9V battery in e.g. a Fluke 7x or 8x).All the best meters do NOT have a transistor tester.Look at specifications, and think about features you need and don't need, and about what you are willing to pay.PM me if a Fluke 8022 will do - we are in the same country after all

author: JanJansen
author_rank: Frequent Contributor
timestamp: April 28, 2017, 02:42:42 pm
content: Thanks Alex, no thanks, i have a old multimeter already, only it is not accurate, i like to measure very accurate voltage,i,m looking to a 5.5 digit or 7.5 digit multimeter now.

author: TiN
author_rank: Super Contributor
timestamp: April 28, 2017, 03:43:18 pm
content: QuoteDepends on what you expect and need. Want warranty and support when needed - buy new.QuoteThere is no such thing as too old. You can use 40 year old nixie tube DMM and it can be still better than brand new cheapie. But older gear need more care, and servicing more likely than not.QuoteOf course it can have lots of problems, from tiny ones like bad cable contact to the huge clusterfails like unstable custom hybrids, unobtainable ICs, burnt holes in PCB,or hidden intermittent issues.To know it's good you need to know what DMM can do and cannot, and have other (often expensive) equipment to be able test that multimeter. Performance test procedures usually listed in user's manual, however even handhelds rely today on multifunction calibrators like Fluke 5520 or 5700A, because many ranges and many functions available. Since you asking questions like above, you unlikely to be prepared to know how much those cost.QuoteFancy LCDs, touchscreens, Bluetooth and other rubbish, usually not related to DMM function directly.Old ones from top tier brands usually better built, have nice beefy chassis (which can be PITA to send/haul over the lab), often many discrete-based circuits instead of two chips with custom firmware. There are cons and pros either team, pick what you need more. Some of old DMMs (designed in 80's-90s still kicking ass of any new DMM for specific purpose uses).QuoteEven if you buy brand new meter, trouble still can get you (bugs in linux firmware, poorly designed cost-down circults, EMI/RFI issues, etc).What is your very accurate voltage source, that you looking into 5.5-7.5 digit meter? (You do understand there are 10-20 times price difference between 5.5 and 7.5 meter, right?)

author: JanJansen
author_rank: Frequent Contributor
timestamp: April 28, 2017, 03:52:11 pm
content: Ok, i buy a new 5.5 or a second hand 7.5 is what i mean.I dont need the 7.5 only it is half the price of the 5.5 i like new.

author: TiN
author_rank: Super Contributor
timestamp: April 28, 2017, 04:30:03 pm
content: I'll be selling Keithley 2001 (calibrated and tested) in few weeks

author: JanJansen
author_rank: Frequent Contributor
timestamp: April 28, 2017, 04:35:31 pm
content: How much ?