I too ordered the meter via Amazon for $120. After 14 months, I noticed missing segments in the bar graph. I called them and they exchanged it no questions asked. They paid shipping both directions. I think it’s a great value compared to my Fluke 28-II. The CEM meter now lives in my RV go-bag.
Thank you for the great review. I just bought a Southwire 14070t and it looks like it was built by CEM. Its a nice meter so far and this review gives me some confidence in the UL / CAT rating. I have never seen as thorough a review of a meter. Very impressed and humbled.
I got my CEM DT9939 from Ruby Electronics for under $130 shipped. I bought it to keep in my RV, where I wanted a water proof meter. I’ve dropped it, kicked it across the ground, and other forms of inadvertent torturous handling. Still works great. A pretty good value for my usage.
Hey Steven. I had to retire my oldest CEM after someone borrowed it and broke two of the input connectors. That meter I think it now 8 years old and has had a hard life.
Thank you, Joe. You just saved me about 150 bucks, and more. I was going to order the Extech DMM, but after watching your video, it was no-brainer to decide for the CEM DMM.
Joe, this stuff is just such a pleasure to watch. You have an understated tone of a gentleman who has seen some stuff, and done some stuff :) It’s like James Bond, except the fireworks are real, and what’s in your head is worth more than the sports car. Running into you on CZcams was like an early birthday present. Do what you do, don’t mind whatever trolls (intentional or not) are seen passing, and know that what you do is highly appreciated. Great stuff, nothing more, nothing less.
After weeks of looking for a reasonably priced feature rich hi rez meter, that one seems to fit the bill.. Just snagged the last one off amazon. I look forward to adding it to my bench. Thank you sir for your insight and thorough testing.
Hey Tim, glad to help. I have a friend who had just ordered one today as well. It was a very good deal for those who got in on it. Maybe they will get more of them.
I know this is an older video, I might have even commented before. Anyway my Extech came with a problem but I think it had been previously opened as the internal packaged items were in some cases not packaged. I got a refund, and in the meantime I saw the CEM version for much less. I went with the CEM version and it was a blue body like the unit you are displaying. The USB Wireless worked fine and it's been a great meter for 2 years now. I am careful with the knob and only turn it carefully and slowly because the internals are kinda sketchy. Same is true of the Extech though. I love the store feature, and the USB feature is great for actual scope like tracking of the chosen data. Thanks for this review all those years ago, it helped me then and I'm using it today.
This is a great test video keep up the good work. I did get lost a little bit but after watching 3 or 4 times I got the logistics of the testing. The EXTECH EX540 that you got from that supplier is a USED meter. They buy used and demo models and sell them as NEW. How are they getting away with it I DO KNOW, but they are doing it. You said yourself that it had been opened before that should have been a clear sign that your test would not be a FAR test with an already damaged meter. Think about it. To have a real test to be FAR it should be done with ALL NEW METERS, I'm just saying.
wow... very honest review.. at the end Extech as brand has the same specifications as their Chinese brothers.... I'll go for the cheapest ones... thanks for the video
No problem. Glad you enjoyed it. I've used these meters in more recent videos. It's too bad Ruby raised the price. $120 for this meter was a great deal.
Great videos Joe, and so informative. I do have a question with regards to the cem 9939 and the Fluke 115. I did see in the 115 video that it failed out of the gate but sure came on strong at the end and finished very well. Given these two meters and knowing that the 115 has a lot of basic functions but the 9939 has many additional functions would you recommend one over the other? Are they both equally as safe to operate? They both appear to be priced about the same. Thank you so much and looking forward to more videos. Also from some of your videos it appears that you may be a ham radio operator as am I, ARS NI6J.
Great review, as always. I am looking for a new meter and I was going to buy the EVV blog one, but it's sold out here in the states. I was about to buy the DT-9939 and they raised the price to $159.95 ---grrr---. still a good deal though. .
Hello Joe...I totally enjoy your "shakedown" of various Multimeters and I find your topics and videos to be extremely informative. I have purchased one of the CEM DT-9939 Meters and I am relatively happy with it. I am also thinking that I have found at least two potential "bugs" or glitches in the firmware...and I am not totally sure it is only my particular unit. First potential bug is while in the "Volts DC" setting, if you press and hold the "Store" "< Recall" button for more than about 2 seconds, the meter locks up...displays all "00000" both in the main display as well as the "Min and Max" displays...no other buttons are functional except the "Exit" button. Second potential bug...while in "Volts DC" mode, the "Peak HOLD" function does not seem to be accessible. If you get a chance to check this potential issue out, please feel free to contact me either by responding here or by email. If by email I will be happy to give you an email address for myself...👍🏼🙂
The meter should have came with a manual. If not I strongly suggest downloading and reading it. Holding the store recall for more than 2 seconds activates the read back function. Assuming nothing was recorded, the only thing you could do is exit. If you had recorded data, as the manual states, you would increment/decrement through the data using the +/- buttons. The peak hold is used in the AC modes. Yes, it can read the DC values in the AC mode. 12Vrms = ??DCV. This is actually one of the faster, if not the fastest meter I own for catching glitches. Still, it's not a feature I would use as it's really a job for the scope. You can see how it stacks up against a few other meters here: czcams.com/video/mzBDgxkO3HE/video.html Enjoy the new meter and take the time to read how to use it.
@@joesmith-je3tq Thank you for the very speedy response, I am looking forward to getting more familiar with this Meter. I did read in the Owners Manual however...that the "Peak HOLD" feature is available in the AC, DC and Current modes...I guess i might be reading/interpreting the "jargon" incorrectly...😁...I will go back and read it again...👍🏼
What I am suggesting is that you place the meter in the ACV mode, enable the peak hold, then apply a DC voltage from your 9V battery. You will find it captures the 9V DC. Keep in mind you will need to manually range the meter. You can also have an AC signal applied, or some biased AC signal, all with the AC function selected. The meter won't care. It's just looking for the peak. Try it.
The Vichy is one of the very few meters I looked at that failed the basic static test. In that respect, it fits right in with most UNI--Ts. I have no use nor would I ever recommend any meter with glass fuses like the VC99. Not to mention the VC99 has not been certified. I'm sure there are people who feel the VC99 is a good value. I'm just not one of them.
Bacana, here in Brazil the resources to good products is difficult. It had one of the IMPAC representative model IP337T. I do not even know who is the manufacturer of this device, but to fix motherboards of notebooks was useful. Then I bought the VC99 for $ 8.19 kkk anniversary promotion. I could not let it go. Big hug.
My first meter was a VTVM. The second was from Radio Shack and was also analog. I did a fair amount of work using those meters and the VC99 would have been a BIG step up. Here we get these free meters from Harbor Freight. Like the VC99, not real robust. Unlike the VC99, there is NO fuse for the large shunt!! I have a really cheap Mastech that I use for low voltage car/motorcycle work. It has ceramic fuses but the input protection is poor. It has survived the ESD test but that's about it.
@@joesmith-je3tq Nothing can be as much fun as tuning a Hayabusa with an analog meter from RadioShack :P On that note, I miss being able to walk into a Radio Shack and pickup a simple part. Too bad they went out of business.
Thanks, Joe! Could you share the design of your test box you used for the resistance/diode/capacitance tests? I would love to build one of those. Thanks for all of your videos!
Hi Joe, great review again! I'm already owning the BM869s and have a much older Metrix MX53C. I've been wondering yes or no to add another DMM to my 'collection' on the bench and was considering the BM235 which is only 90EUR here in Europe. The DT9939 is 156EUR. So for the reason of LoZ, remote sensing and costs I'm leaning towards the BM235. (although the DT9939 has remote data logging :-) What would be your advice Joe?
Thanks I'm glad you enjoyed it. What equipment people need/buy is really up to them. For some, the HF free meter may be fine. Me personally, like I said at the end of the video still like the BM869s over every meter I have looked at.
Bought the BM235 and though not tested yet in full I really like the form factor and the options it has. Nice addition to the BM869s. Dave said you simply can not have enough DMM's so.... :-)
I like the 235. Price wise, it's not a bad deal and I like the small package and easy to read display. It would make a good meter for my own general outdoor use but for my indoor hobby, the BM869s has been good enough to where I seldom use my bench meters anymore.
Hi Joe, I've been, although quickly, comparing the datasheets between the 235 and 869s and in terms of accuracy there is difference the 869s uses a sec like 0.5% + 60d for AC 50Hz 230V and the 235 has 0.7% +3d. Not so easy to compare then. the 869s is more feature rich and has a better accuracy. I'm not too impressed with the EF detection on the 235 so far. I've ran through the house where "measuring" the location where 230line is running but when it's tucked in behind plaster, brick or even wood/plasterboard it's getting very inaccurate in terms of location. Not sure what to make of it. Did you try that feature perhaps?
Are you using the higher sensitivity setting for the EF? I did try it when I made the video review for the 235. But, that was just through air. I hate meter specs. Is it + or +-? Is it absolute, of reading, of full scale? Is it over the specified operating temperature?..... You would think they would tie the details down.
Hey Joe - I got a DT-9939 last week and it measures voltages a bit low from a few different references. Can I align this sucker? I will watch the video again but I can't remember if I can adjust this thing myself. Thanks!
If you have access to a reference standard, I don't know why not. CEM or Extech can supply the alignment procedure. Strange you would get a new one that is out of spec. I would imagine the standards used to align them are NIST traceable.
Yes, that is correct. And yes that was the SN for the 9100. The sheet is for a range of multimeter serial numbers. This meter's serial number falls outside of that range. It's a feel good paper, nothing more.
Joe, have you investigated or tested the CEM DT-9989? It seems to be an upgrade of the 9939, even approaching Uni-T UT181A, with built-in Bluetooth, 50,000 count, and single channel oscilloscope functions. The CEM web site mentions the 9989 has Surge Protection: 8kV peak per IEC 61010. It's $399.00 "Prime" on Amazon. Also sold as the Daktakom TRUE RMS MULTIMETER& OSCILLOSCOPE model AMM-4189. Price much higher on eBay for some reason...
just picked up a extech ex540 new old stop from ebay. still covered and does appear to be new. mine is version 5 so it looks like its tha same as your original. I like the tri display for use of the min max, I find it useful. I bought it for $60 so cant go wrong :)
Don, the only problem I have had with my original one is when I loaned it out once, the person turned the know past the dead stops and cracked the plastic hex shaped area where the shaft fits through. I rebuilt the hex using epoxy and then built this area up. A few times its been returned with blown fuses. I personally have abused it a fair amount in the five years I have had it and as you can see in the following video, it still works fine. A bit discolored now from the sun. czcams.com/video/Yih7D23z7vE/video.html
No problem. I really like the RF link on this meter. It works very well from 10 feet or so away and uses little current compared with the Gossen. If you use Labview, I did post how to decode the serial data. Enjoy your new meter.
Hi Joe. In this kind of input protection using back-to-back transistor (like diode), besides the leakage current, the other importante parameter is the "Vebo" (Voltage emitter base breakdown voltage)? The NPN 2N3904 is a good choice to this use? In a different way I saw this app note showing the use of the 2N3904, but instead of back-to-back using just the base-collector junction (www.analog.com/media/en/training-seminars/tutorials/MT-069.pdf) Can you indicate or share some material about this kind of protection? I think a vidou about this would be awesome. Thank you.
Hi 1. +1 about circut protection (clamps) info, and diagnostic + repair after HW testing and damage. 2. I have not eat few month and bought 869s ))), so now i am happy man. But i will be much happier if i will understand how to fix my fried multimeter (spoke earlier), because feeling and understanding how to fix some electronics is good thing! 3.If it is not a secreet, there you are study at?
Hey Fisherman. Hope you are enjoying the new meter. Before you try it, if I show the Brymen surviving at several KV, that is a very short pulse. This does not mean it would survive being connected to a high current high voltage source, even if the voltage is lower than I test to. I suspect the Brymen would fail just like your UNI-T when connected to the secondary of a MOT. Did you try contacting UNI-T to see if they would repair it?
Of course now i am understanding, what you should read some shematics, and think twice, before "stick something to somethere". I hope it will never happen with my new multimeter! I have tried couple times to contact to unitrend, but they use "ostrich policy" in their job, so i failed to do it. Of course, i could spent money, for to fix UT71D in any repair center, but it is much interesting to learn something new, and to fix it by my self. So i have tried to fix it but did only worse. I even bought hotair gun, ans soldering stuff, but lack of special knowledges do not allow me to understand that i did wrong. It is easy just in your videos - fried - couple minutes - fixed! Piece of cake! ))) About CEM and Extech (overall). Previously i thought, that Extech is well known brand like Fluke, producing just quality products. But now it is clearly see, that china garbage can have any well known label on it, and do not pass even EMC from grill ignitor. So that is why people have to watching teardowns and HV tests, for to analize what they are going to buy. Is it safe, or not? Would it work few years or not? Have you thought to buy Gossen meter for HV testing or it is far from budget? Maybe used one?
Playing with a MOT without some understanding could lead to not only a meters failure but to your death. We had a teenager that was killed over the summer with one. Too bad about UNI-T. I would have thought they would be big enough to have some sort of service center by now. There was a member on EEVBLOG attempting to repair one. Not sure if that was you. I don't think they were able to get theirs working. I've been able to repair a few of them but most were beyond being salvaged. The TPI 194II is one that I kept that is damaged. One pin of the controller IC is leaking and throwing off some of the readings. Most of it works so I kept it. The company does not have replacement parts for it.
Agree about how slow it is and it failed a little on the low side. It did hold up better than the Fluke 87V. I think another person I know picked the CEM up as well. Just double check their workmanship before you put it into service.
Joe, I truly hope you can test the CEM DT9989, also available from Ruby. It looks like a very good copy of the Fluke 289 but with built-in BlueTooth and a simple Oscilloscope function. It even has an Auto Hold feature very much like the Auto Hold on Fluke meters. The feature has some limitations, including speed of measurement and a somewhat hidden adjustment of the sensitivity. To measure 0.100 volts and 1.5 volts alternatively using the Auto Hold, the sensitivity must be set to 1%. Then it works just like the Fluke, only slightly slower. Sometimes I had to short my leads together prior to making a measurement to get the Auto Hold to recognize a new value. I find Auto Hold to be a great feature not present on my other deluxe meters including the Uni-T 181A and the Brymen 869a. This is a VERY useful feature when measuring power distribution panels, circuit boards , etc. when you can't look away for fear of shorting something. Lastly, I just checked Ruby's eBay store and the DT9939 is back to $139.00 with free shipping. It's $159.00 directly from Ruby. Go figure.... Thanks again for the awesome reviews. I still say, you're the engineer's engineer. You've reminded me about so many things I've forgotten over the years. Unfortunately so much being totally digital has spoiled our analog awareness.!
Like most, I normally use the min max for a hold. I saw a person post where they were on their second one of the 9989. They had to keep returning them for quality problems. I'm not too surprised. Their quality has not been as good as it should be.
@@joesmith-je3tq I am interested in your opinion about the devices as a whole, without taking into account any individual, even specific functions. It is clear that one is superior in something, in something else, but these are secondary functions for everyday work. CEM's bargraph is of course terrible, and this is the main disadvantage, I think. If you compare the "old man" with the "baby", the speed of work, workmanship and reliability, as well as ease of use.
@@user-ku4mq2ej5j My opinion is that both meters have their place. Depending on the requirements, one may be better suited than the other. I had found a deal on the CEM meters. $120 USD. That's hard to compete with. I use the RF link and will use a PC to remotely log data with it. I like meters that can display more than one parameter at a time. The peak detect on the CEM is fast but I've never had a use for it. CEMs quality seems hit and miss. I had used one of these meters for several years but the plastics couldn't handle the abuse. The CEMs front end is more robust than many of the low end meters I have looked at but it's far from being able to compete with the higher end brands.
Hi - Sorry but I have a stupid layman question, in watching your testing videos you often make reference to "AC plus DC voltage" mode - I know the difference between the two types of voltage of course, but id like to know the meaning and use of the AC+DC testing mode. I just dont know. Thanks --
It's just the square root of (AC^2 + DC^2). You will find that in pretty much any multimeter manual that supports it. Look at the Fluke 289 manual for example.
Make this video for the UT90A fans. czcams.com/video/aRuI_q_K5RY/video.html Since then the meter has been used in various other tests and continues to function.
I too ordered the meter via Amazon for $120. After 14 months, I noticed missing segments in the bar graph. I called them and they exchanged it no questions asked. They paid shipping both directions. I think it’s a great value compared to my Fluke 28-II. The CEM meter now lives in my RV go-bag.
CEM Instruments is a huge Chinese manufacturer. You will find many of their products that have been re-branded.
When Joe Smith gets to look at your multimeter there ain't no place to hide and it better be good !!
I enjoy watching them fail just like the next person..
The amount of effort you put into reviewing these meters is just unbelievable. FLUKE should hire you as a consultant.
Thank you for the great review. I just bought a Southwire 14070t and it looks like it was built by CEM. Its a nice meter so far and this review gives me some confidence in the UL / CAT rating. I have never seen as thorough a review of a meter. Very impressed and humbled.
I got my CEM DT9939 from Ruby Electronics for under $130 shipped. I bought it to keep in my RV, where I wanted a
water proof meter. I’ve dropped it, kicked it across the ground, and other forms of inadvertent torturous handling. Still works great. A pretty good value for my usage.
Hey Steven. I had to retire my oldest CEM after someone borrowed it and broke two of the input connectors. That meter I think it now 8 years old and has had a hard life.
Thank you, Joe. You just saved me about 150 bucks, and more. I was going to order the Extech DMM, but after watching your video, it was no-brainer to decide for the CEM DMM.
Glad it was useful. Too bad you did not get in on the $120 price. That was a great deal.
Joe, this stuff is just such a pleasure to watch. You have an understated tone of a gentleman who has seen some stuff, and done some stuff :) It’s like James Bond, except the fireworks are real, and what’s in your head is worth more than the sports car. Running into you on CZcams was like an early birthday present. Do what you do, don’t mind whatever trolls (intentional or not) are seen passing, and know that what you do is highly appreciated. Great stuff, nothing more, nothing less.
Enjoy your stay.
Thanks Joe. Good job.
Excellent review, as always! Gonna give this one a try. I really like the "Bait" mode, where you can use it for fishing! ;)
Problem with using the UNI-T for bait, you never know what you are going to catch with it.
After weeks of looking for a reasonably priced feature rich hi rez meter, that one seems to fit the bill.. Just snagged the last one off amazon. I look forward to adding it to my bench. Thank you sir for your insight and thorough testing.
Hey Tim, glad to help. I have a friend who had just ordered one today as well. It was a very good deal for those who got in on it. Maybe they will get more of them.
I know this is an older video, I might have even commented before. Anyway my Extech came with a problem but I think it had been previously opened as the internal packaged items were in some cases not packaged. I got a refund, and in the meantime I saw the CEM version for much less. I went with the CEM version and it was a blue body like the unit you are displaying. The USB Wireless worked fine and it's been a great meter for 2 years now. I am careful with the knob and only turn it carefully and slowly because the internals are kinda sketchy. Same is true of the Extech though. I love the store feature, and the USB feature is great for actual scope like tracking of the chosen data. Thanks for this review all those years ago, it helped me then and I'm using it today.
The plastics are the weak link to this meter. The switch and input jacks were damaged on mine.
The Fluke was the standard used to test calibration on your meter.
This is a great test video keep up the good work. I did get lost a little bit but after watching 3 or 4 times I got the logistics of the testing. The EXTECH EX540 that you got from that supplier is a USED meter. They buy used and demo models and sell them as NEW. How are they getting away with it I DO KNOW, but they are doing it. You said yourself that it had been opened before that should have been a clear sign that your test would not be a FAR test with an already damaged meter. Think about it. To have a real test to be FAR it should be done with ALL NEW METERS, I'm just saying.
I've looked at a few CEM meters. They never do well in these tests. You get what you pay for in this case.
wow... very honest review.. at the end Extech as brand has the same specifications as their Chinese brothers.... I'll go for the cheapest ones... thanks for the video
No problem. Glad you enjoyed it. I've used these meters in more recent videos. It's too bad Ruby raised the price. $120 for this meter was a great deal.
I love the dichotomy. He'll do all these fancy tests and check darn near everything in a methodical way. And then he'll just toss one in a river.
Great videos Joe, and so informative. I do have a question with regards to the cem 9939 and the Fluke 115. I did see in the 115 video that it failed out of the gate but sure came on strong at the end and finished very well. Given these two meters and knowing that the 115 has a lot of basic functions but the 9939 has many additional functions would you recommend one over the other? Are they both equally as safe to operate? They both appear to be priced about the same. Thank you so much and looking forward to more videos. Also from some of your videos it appears that you may be a ham radio operator as am I, ARS NI6J.
There is a FAQ linked in my about page. You may also find it in the description of several of the later videos. That is the place to start.
great job
taking a multimeter for a dunk .. nice review as always
Great review, as always. I am looking for a new meter and I was going to buy the EVV blog one, but it's sold out here in the states. I was about to buy the DT-9939 and they raised the price to $159.95 ---grrr---. still a good deal though. .
Thanks. Just checked and sure enough, they raised the price $40. Oh well, it was a great deal while it lasted.
Hello Joe...I totally enjoy your "shakedown" of various Multimeters and I find your topics and videos to be extremely informative. I have purchased one of the CEM DT-9939 Meters and I am relatively happy with it. I am also thinking that I have found at least two potential "bugs" or glitches in the firmware...and I am not totally sure it is only my particular unit.
First potential bug is while in the "Volts DC" setting, if you press and hold the "Store" "< Recall" button for more than about 2 seconds, the meter locks up...displays all "00000" both in the main display as well as the "Min and Max" displays...no other buttons are functional except the "Exit" button.
Second potential bug...while in "Volts DC" mode, the "Peak HOLD" function does not seem to be accessible.
If you get a chance to check this potential issue out, please feel free to contact me either by responding here or by email. If by email I will be happy to give you an email address for myself...👍🏼🙂
The meter should have came with a manual. If not I strongly suggest downloading and reading it. Holding the store recall for more than 2 seconds activates the read back function. Assuming nothing was recorded, the only thing you could do is exit. If you had recorded data, as the manual states, you would increment/decrement through the data using the +/- buttons. The peak hold is used in the AC modes. Yes, it can read the DC values in the AC mode. 12Vrms = ??DCV. This is actually one of the faster, if not the fastest meter I own for catching glitches. Still, it's not a feature I would use as it's really a job for the scope. You can see how it stacks up against a few other meters here: czcams.com/video/mzBDgxkO3HE/video.html Enjoy the new meter and take the time to read how to use it.
@@joesmith-je3tq Thank you for the very speedy response, I am looking forward to getting more familiar with this Meter.
I did read in the Owners Manual however...that the "Peak HOLD" feature is available in the AC, DC and Current modes...I guess i might be reading/interpreting the "jargon" incorrectly...😁...I will go back and read it again...👍🏼
What I am suggesting is that you place the meter in the ACV mode, enable the peak hold, then apply a DC voltage from your 9V battery. You will find it captures the 9V DC. Keep in mind you will need to manually range the meter. You can also have an AC signal applied, or some biased AC signal, all with the AC function selected. The meter won't care. It's just looking for the peak. Try it.
Excellent work, it makes the same sense with Vichy VC97 or VC99
The Vichy is one of the very few meters I looked at that failed the basic static test. In that respect, it fits right in with most UNI--Ts. I have no use nor would I ever recommend any meter with glass fuses like the VC99. Not to mention the VC99 has not been certified. I'm sure there are people who feel the VC99 is a good value. I'm just not one of them.
Bacana, here in Brazil the resources to good products is difficult. It had one of the IMPAC representative model IP337T. I do not even know who is the manufacturer of this device, but to fix motherboards of notebooks was useful.
Then I bought the VC99 for $ 8.19 kkk anniversary promotion.
I could not let it go.
Big hug.
My first meter was a VTVM. The second was from Radio Shack and was also analog. I did a fair amount of work using those meters and the VC99 would have been a BIG step up. Here we get these free meters from Harbor Freight. Like the VC99, not real robust. Unlike the VC99, there is NO fuse for the large shunt!! I have a really cheap Mastech that I use for low voltage car/motorcycle work. It has ceramic fuses but the input protection is poor. It has survived the ESD test but that's about it.
@@joesmith-je3tq Nothing can be as much fun as tuning a Hayabusa with an analog meter from RadioShack :P
On that note, I miss being able to walk into a Radio Shack and pickup a simple part. Too bad they went out of business.
@@tech29X I tune mine with a PC.
Thanks, Joe! Could you share the design of your test box you used for the resistance/diode/capacitance tests? I would love to build one of those. Thanks for all of your videos!
Hey David, there is a FAQ in the About and Discussions pages. In there I provide the brands of the parts I use.
Thanks again - I will take a look. I appreciate your efforts and videos very much.
No problem. If you still have questions after checking out the FAQ, feel free to ask.
Hi Joe, great review again! I'm already owning the BM869s and have a much older Metrix MX53C. I've been wondering yes or no to add another DMM to my 'collection' on the bench and was considering the BM235 which is only 90EUR here in Europe. The DT9939 is 156EUR. So for the reason of LoZ, remote sensing and costs I'm leaning towards the BM235. (although the DT9939 has remote data logging :-) What would be your advice Joe?
Thanks I'm glad you enjoyed it. What equipment people need/buy is really up to them. For some, the HF free meter may be fine. Me personally, like I said at the end of the video still like the BM869s over every meter I have looked at.
Bought the BM235 and though not tested yet in full I really like the form factor and the options it has. Nice addition to the BM869s. Dave said you simply can not have enough DMM's so.... :-)
I like the 235. Price wise, it's not a bad deal and I like the small package and easy to read display. It would make a good meter for my own general outdoor use but for my indoor hobby, the BM869s has been good enough to where I seldom use my bench meters anymore.
Hi Joe, I've been, although quickly, comparing the datasheets between the 235 and 869s and in terms of accuracy there is difference the 869s uses a sec like 0.5% + 60d for AC 50Hz 230V and the 235 has 0.7% +3d. Not so easy to compare then. the 869s is more feature rich and has a better accuracy. I'm not too impressed with the EF detection on the 235 so far. I've ran through the house where "measuring" the location where 230line is running but when it's tucked in behind plaster, brick or even wood/plasterboard it's getting very inaccurate in terms of location. Not sure what to make of it. Did you try that feature perhaps?
Are you using the higher sensitivity setting for the EF? I did try it when I made the video review for the 235. But, that was just through air. I hate meter specs. Is it + or +-? Is it absolute, of reading, of full scale? Is it over the specified operating temperature?..... You would think they would tie the details down.
Joe, the nec plus ultra of instruments testing.
Hey Joe - I got a DT-9939 last week and it measures voltages a bit low from a few different references. Can I align this sucker? I will watch the video again but I can't remember if I can adjust this thing myself. Thanks!
If you have access to a reference standard, I don't know why not. CEM or Extech can supply the alignment procedure. Strange you would get a new one that is out of spec. I would imagine the standards used to align them are NIST traceable.
only on this chanel, testing meters with water current
Current, I see what you did there! haha
The Fluke 9100 on the cal sheet is the meter they used to do the calibration. Well, claimed to have done.
Yes, that is correct. And yes that was the SN for the 9100. The sheet is for a range of multimeter serial numbers. This meter's serial number falls outside of that range. It's a feel good paper, nothing more.
Precisely! That's the difference between the real one and the one you pay $120 for.
The "real one"? Do you feel the one marked CEM is a knockoff? If so, why? Just the cert?
Joe, have you investigated or tested the CEM DT-9989? It seems to be an upgrade of the 9939, even approaching Uni-T UT181A, with built-in Bluetooth, 50,000 count, and single channel oscilloscope functions. The CEM web site mentions the 9989 has Surge Protection: 8kV peak per IEC 61010. It's $399.00 "Prime" on Amazon. Also sold as the Daktakom TRUE RMS MULTIMETER& OSCILLOSCOPE model AMM-4189. Price much higher on eBay for some reason...
I think someone on EEVBLOG bought one that came in defective. Maybe try a search over there.
just picked up a extech ex540 new old stop from ebay. still covered and does appear to be new. mine is version 5 so it looks like its tha same as your original. I like the tri display for use of the min max, I find it useful. I bought it for $60 so cant go wrong :)
Don, the only problem I have had with my original one is when I loaned it out once, the person turned the know past the dead stops and cracked the plastic hex shaped area where the shaft fits through. I rebuilt the hex using epoxy and then built this area up. A few times its been returned with blown fuses. I personally have abused it a fair amount in the five years I have had it and as you can see in the following video, it still works fine. A bit discolored now from the sun.
czcams.com/video/Yih7D23z7vE/video.html
lol abused it is and yse I learned of this meter from your videos. I enjoy them. Thanks for the entertainment and knowledge
No problem. I really like the RF link on this meter. It works very well from 10 feet or so away and uses little current compared with the Gossen. If you use Labview, I did post how to decode the serial data. Enjoy your new meter.
Hi Joe.
In this kind of input protection using back-to-back transistor (like diode), besides the leakage current, the other importante parameter is the "Vebo" (Voltage emitter base breakdown voltage)? The NPN 2N3904 is a good choice to this use? In a different way I saw this app note showing the use of the 2N3904, but instead of back-to-back using just the base-collector junction (www.analog.com/media/en/training-seminars/tutorials/MT-069.pdf)
Can you indicate or share some material about this kind of protection? I think a vidou about this would be awesome.
Thank you.
I've done a few videos on how meters are typically protected. Dave at EEVBLOG has done one as well. 3904 is fairly common.
Hi
1. +1 about circut protection (clamps) info, and diagnostic + repair after HW testing and damage.
2. I have not eat few month and bought 869s ))), so now i am happy man. But i will be much happier if i will understand how to fix my fried multimeter (spoke earlier), because feeling and understanding how to fix some electronics is good thing!
3.If it is not a secreet, there you are study at?
Hey Fisherman. Hope you are enjoying the new meter. Before you try it, if I show the Brymen surviving at several KV, that is a very short pulse. This does not mean it would survive being connected to a high current high voltage source, even if the voltage is lower than I test to. I suspect the Brymen would fail just like your UNI-T when connected to the secondary of a MOT. Did you try contacting UNI-T to see if they would repair it?
Of course now i am understanding, what you should read some shematics, and think twice, before "stick something to somethere". I hope it will never happen with my new multimeter!
I have tried couple times to contact to unitrend, but they use "ostrich policy" in their job, so i failed to do it. Of course, i could spent money, for to fix UT71D in any repair center, but it is much interesting to learn something new, and to fix it by my self. So i have tried to fix it but did only worse. I even bought hotair gun, ans soldering stuff, but lack of special knowledges do not allow me to understand that i did wrong. It is easy just in your videos - fried - couple minutes - fixed! Piece of cake! )))
About CEM and Extech (overall). Previously i thought, that Extech is well known brand like Fluke, producing just quality products. But now it is clearly see, that china garbage can have any well known label on it, and do not pass even EMC from grill ignitor. So that is why people have to watching teardowns and HV tests, for to analize what they are going to buy. Is it safe, or not? Would it work few years or not?
Have you thought to buy Gossen meter for HV testing or it is far from budget? Maybe used one?
Playing with a MOT without some understanding could lead to not only a meters failure but to your death. We had a teenager that was killed over the summer with one. Too bad about UNI-T. I would have thought they would be big enough to have some sort of service center by now. There was a member on EEVBLOG attempting to repair one. Not sure if that was you. I don't think they were able to get theirs working. I've been able to repair a few of them but most were beyond being salvaged. The TPI 194II is one that I kept that is damaged. One pin of the controller IC is leaking and throwing off some of the readings. Most of it works so I kept it. The company does not have replacement parts for it.
So which DMM do you recommend for $180 or less? (for hobby, electronics)
If you would take the time to read the FAQ, you will note that I do not normally offer recommendations.
Is CEM OEM for Extech & Sonel Instruments??
I have never heard of Sonel but Extech does rebrand some CEM products like the one shown during this video. Wasn't that clear?
Where did you get the plugs for mA jack on you Brymen?
These came from a dead meter. The CEMs had these same ones. I expect from one of the Extechs I looked at.
Great! I'm getting a CEM DT9939 next week. Thanks for a great review. Bummer about the slow continuity test.
Agree about how slow it is and it failed a little on the low side. It did hold up better than the Fluke 87V. I think another person I know picked the CEM up as well. Just double check their workmanship before you put it into service.
Joe, I truly hope you can test the CEM DT9989, also available from Ruby. It looks like a very good copy of the Fluke 289 but with built-in BlueTooth and a simple Oscilloscope function. It even has an Auto Hold feature very much like the Auto Hold on Fluke meters. The feature has some limitations, including speed of measurement and a somewhat hidden adjustment of the sensitivity. To measure 0.100 volts and 1.5 volts alternatively using the Auto Hold, the sensitivity must be set to 1%. Then it works just like the Fluke, only slightly slower. Sometimes I had to short my leads together prior to making a measurement to get the Auto Hold to recognize a new value.
I find Auto Hold to be a great feature not present on my other deluxe meters including the Uni-T 181A and the Brymen 869a. This is a VERY useful feature when measuring power distribution panels, circuit boards , etc. when you can't look away for fear of shorting something.
Lastly, I just checked Ruby's eBay store and the DT9939 is back to $139.00 with free shipping. It's $159.00 directly from Ruby. Go figure....
Thanks again for the awesome reviews. I still say, you're the engineer's engineer. You've reminded me about so many things I've forgotten over the years. Unfortunately so much being totally digital has spoiled our analog awareness.!
Like most, I normally use the min max for a hold. I saw a person post where they were on their second one of the 9989. They had to keep returning them for quality problems. I'm not too surprised. Their quality has not been as good as it should be.
How does this CEM DT9939 compare to the Brymen BM789 in your opinion?
Using what metrics? Most of the details may be found in the two manuals.
@@joesmith-je3tq I am interested in your opinion about the devices as a whole, without taking into account any individual, even specific functions. It is clear that one is superior in something, in something else, but these are secondary functions for everyday work. CEM's bargraph is of course terrible, and this is the main disadvantage, I think. If you compare the "old man" with the "baby", the speed of work, workmanship and reliability, as well as ease of use.
@@user-ku4mq2ej5j My opinion is that both meters have their place. Depending on the requirements, one may be better suited than the other. I had found a deal on the CEM meters. $120 USD. That's hard to compete with. I use the RF link and will use a PC to remotely log data with it. I like meters that can display more than one parameter at a time. The peak detect on the CEM is fast but I've never had a use for it. CEMs quality seems hit and miss. I had used one of these meters for several years but the plastics couldn't handle the abuse. The CEMs front end is more robust than many of the low end meters I have looked at but it's far from being able to compete with the higher end brands.
33:05 I am not sure that it is the right bait for electric eels :-)
Seems like a pretty good meter. It's a shame about the slow continuity though.
Yeah, and he even used ProbeMaster cables, which are nice ones and usually makes the continuity test a bit faster. Bummer...
@@JackZimmermann How fast do you need?
Did any of these meters pass the ice fishing test?
I don't think I ever tossed one of these in.
Hi - Sorry but I have a stupid layman question, in watching your testing videos you often make reference to "AC plus DC voltage" mode - I know the difference between the two types of voltage of course, but id like to know the meaning and use of the AC+DC testing mode. I just dont know. Thanks --
It's just the square root of (AC^2 + DC^2). You will find that in pretty much any multimeter manual that supports it. Look at the Fluke 289 manual for example.
yambo59 -an a/c sin can ride on a dc voltage. Without ac+dc you have to measure separate and calculate
That UT90A deserved so much better...
Make this video for the UT90A fans. czcams.com/video/aRuI_q_K5RY/video.html Since then the meter has been used in various other tests and continues to function.
UT90A in Terminator mode. :)
I've abused my UT90A more than any other meter. It's still in working condition today, waiting for the next abusive test.
"Manufactured by Fluke" as 87VC, 287C, 289C etc.
Sorry, I have no idea what your quote is referring to.