Author Topic: Multimeters and portable digital oscilloscope from CEM Instruments (Read 12798 times)

pascal_sweden · « **on:** May 24, 2015, 11:48:23 pm »

How do the multimeters and portable digital oscilloscope from CEM Instruments perform?

They look rather nice!

CEM DT-9987: 50K count Multimeter CAT IV 600V, CAT III 1000V (Waterproof IP-67/Bluetooth)

Website from manufacturer:
http://www.cem-instruments.com/en/pro/pro-825.html
Available on Amazon for 269 EUR:
http://www.amazon.de/CEM-Multimeter-DT-9987-50000-Counts/dp/B00T7WQ5KG

CEM DT-9989: 50K count Multimeter CAT IV 600V, CAT III 1000V and 10MHz/50MS/s digital oscilloscope (Waterproof IP-67/Bluetooth)

Website from manufacturer:
http://www.cem-instruments.com/en/pro/pro-824.html
Available on Amazon for 396 EUR:
http://www.amazon.de/CEM-Digital-Multimeter-Oszilloskop-Bluetooth/dp/B00T6J72QG/ref=pd_sim_sbs_60_1?ie=UTF8&refRID=0ZMVDRCH7W4AQZCXWXAX

CEM DT-990S: 40MHz/200MS/s/125Kpoints mem digital oscilloscope

Website from manufacturer:
http://www.cem-instruments.com/pro/pro-845.html
Available from Chinese distributor. Price unknown.
http://www.diytrade.com/china/pd/10801508/40_MHz_Handheld_Digital_Oscilloscope.html

Marco · « **Reply #1 on:** May 25, 2015, 12:24:21 am »

Colour LCD ... will eat batteries.

pascal_sweden · « **Reply #2 on:** May 25, 2015, 03:31:33 pm »

Apparently these multimeters come with a big LiPo battery (2400 mAh)

https://www.youtube.com/watch?list=UUrPuVDBtQIxgzj8_En81r0A&feature=player_detailpage&v=zzfYm2DorWU#t=106

Not exactly the same model of multimeter, but the same manufacturer, and most likely they will use the same type of battery in the higher-end models.

The fuses seem acceptable, and the construction of the connectors inside as well. However I am not impressed at all about the PCB quality. Looks a bit messy! There is also a component sitting on the back that can get loose any moment. This is an older model though, so let's hope they have improved on this in the mean time.

ivan747 · « **Reply #3 on:** May 25, 2015, 09:57:20 pm »

What's the price for these?

pascal_sweden · « **Reply #4 on:** May 29, 2015, 07:19:45 pm »

The prices are available on Amazon. It seems however that the portable scope with 20 MHz is a discontinued product. The combi multimeter and scope only supports 10 MHz, but has a nice form factor.

pascal_sweden · « **Reply #5 on:** May 30, 2015, 09:29:26 am »

I have contacted the manufacturer to check if they have a distributor in Europe and if they still deliver the 20 MHz scopemeter. Will post their feedback here when they come back to me.

firehopper · « **Reply #6 on:** May 30, 2015, 10:01:34 am »

the first one looks almost exactly like a fluke 289

Neverther · « **Reply #7 on:** May 31, 2015, 05:51:35 am »

I got:
DT-9918T as generic meter.
DT-9985 for testing ground faults on heaters/motors (tripping RCDs started to annoy after attempted repairs, got it at half price on sale) good voltage measurement and other stuff, continuity is slow.
DT-3351 for testing alternators and starters (also got it for half the price on same sale).
DT-3218 in car incase I need it (replaced Kaise SK-6590, would have preferred the newest SK-6592 but I could not get it anywhere, the CEM meter is huge when compared to the small Kaise).

Yellow bodies as they were made before the Fluke thing.
They are pretty good for the price.

Inside the 9918t, look into the old 100$ multimeter shootout and you might see something.
I have looked inside the 3351, but no idea where the pictures are.

pascal_sweden · « **Reply #8 on:** May 31, 2015, 11:52:02 am »

It seems they have fairly good protection with 5 MOVs: 2 on one side of the board, 3 on other side.
The connectors are connected pretty well with a screw.

Lightages · « **Reply #9 on:** May 31, 2015, 01:03:58 pm »

CEM makes some pretty good designs with good features and for reasonable prices some times. They are also the OEM for some other companies too. For example Extech re-brands some of the models for the EX series. CEM and Extech have a mixed history with quality control. Dave received a meter with a broken circuit board that was fixed with a bodge wire. Others have had problems with very bad solder joints, loose screws, control dials falling off, etc. The opinions and reviews with these problems are easy to find with a few searches. There are also many happy people with CEM products.

pascal_sweden · « **Reply #10 on:** May 31, 2015, 01:45:28 pm »

Apparently some people tried to get a sample in 2012 without success:
http://www.ittsb.eu/forum/index.php?topic=330.0

pascal_sweden · « **Reply #11 on:** June 03, 2015, 02:08:51 pm »

No feedback from CEM yet, but I will keep this posting updated.

ozcal · « **Reply #12 on:** July 07, 2016, 04:33:49 am »

We bought 10 of the DT-9989 meters nearly 2 years ago. Would not recommend. We've had endless quality issues with them.
Missing screws, battery not charging, readings out of spec (new OOTB), intermittent dropouts, incorrect units displayed (mA when uA selected). Yesterday, I even had one flip its display (mirrored).

Bobson · « **Reply #13 on:** July 08, 2016, 06:39:12 pm »

I have DT-9979. Assembly quality is good, precision is up to specs.

Cons: there is no known possibility to upgrade the firmware, and some of the features described in the built-in help are unavailable. Also, there are some Chinglish grammar errors. Trends could not be zoomed and traced. Clock precision is bad - upto several minutes per month. BT logging speed could not be changed.

Pros: it is easy to calibrate, bluetooth interface is working. Price is rather low. Display is so-so without backlight, but very good with it. Battery life upto 200 hours in logging mode. IP67 waterproof. Manual says 7 hours battery life, but my experience show 4 times better without backlight.

Summary: poor man's version of Fluke 289 with better display and BT.

Hydrawerk · « **Reply #14 on:** July 08, 2016, 08:26:05 pm »

As a poor man I would buy a decent Brymen for the price of DT-9979. I think I would hardly need a graphic DMM.

Bobson · « **Reply #15 on:** July 08, 2016, 08:46:08 pm »

Graphing is usable on DT-9987 and DT-989, but not of much help on DT-9979 due to restrictions (one static graph w/o marks, trace and zoom).

But I don't know any Brymen model which has BT connectivity, easy calibration, events and clock. They are in the completely different league, IMO.

Hydrawerk · « **Reply #16 on:** July 08, 2016, 09:40:09 pm »

OK, for some time-correlated datalogging stuff the CEM might be good.

Bobson · « **Reply #17 on:** July 08, 2016, 10:47:17 pm »

Not only datalogging. Top CEM models have good resolution, better uV, pF and MHz ranges than any Brymen. I've read bad CEM quality reports, but no statistics. Brymen has better QC, supposedly. CEM products have rather high prices (higher than UNI-T) and are hard to obtain. Definitely, good software could improve functionality very much, but CEM lacks resources as I can see.

Would add some more details to Fluke 289/CEM DT-9979 comparison:

Compared to Fluke 289, CEM DT-9979 is not much cheaper (I can get second-hand Fluke 289 for $350, DT-9979 new for $350 and second-hand for $200), and have lower quality.

CEM has much better display, faster boot time, BT and software is free. It uses built-in lithium battery. There is no known available calibration manual, but using Fluke's one can help.

Fluke has much better trend capture analysis built-in (however, using BT logging and PC/Android program with CEM you can do better), you can buy BT adaptor for $$. Also, Fluke has LowZ, conductivity, AC smoothing. It uses AA cells (sometimes it is better than built-in lithium, sometimes not). It has higher diode test voltage - 7 Volts compared to 3.2 and signals on wrong input jacks used. FLUKE HAS AN UPGRADEABLE FIRMWARE!! It has problematic built-in backup battery, thou.

If you have money and can cope with display problems, Fluke is much better.

Hydrawerk · « **Reply #18 on:** July 09, 2016, 12:00:47 am »

Yes, all the Brymen multimeters can measure max 1MHz frequency or less. It is probably because of the internal high voltage protection that has little impedance for high frequencies. My Unit UT70A (2009) can measure 10MHz and my Metex M-3650D can measure 20MHz. These two DMMs are rather basic, they have no autorange and no True RMS.

Quote

Fluke has LowZ, conductivity, AC smoothing. It uses AA cells (sometimes it is better than built-in lithium, sometimes not)

I prefer it. You can always use some accumulators like Eneloop advanced NiMh.

skander36 · « **Reply #19 on:** March 03, 2020, 08:56:09 pm »

Hi,
This days CEM DT 9979 is 225 E on Amazon .
Consider this , it is an option to Fluke 289 ? . Fluke is simply too expensive .
UNI-T DT181A is suddenly over 400 E almost as much as Fluke . They think that color display is make it worth ...

Thank you .

Andrus · « **Reply #20 on:** March 16, 2025, 08:44:56 pm »

Hello!

I am very satisfied with this CEM9989 !

as its reviewed in forum, there actually 2 boards inside: one for multimeter and other for scope.
What I really like : very fast and precise multimeter for measuring voltages, current and ohms. It goes for 50 Mohm and voltage for 1000 V / scope 600 V. 50000 count . Scope I use especially for CAN signal measurement: is it OK looking waveform or not.
And inputs are same, no need to switch between scope and multmeter outputs.
Somehow everything feels logical. menu naviagation and everything.

Its already 10 years old and still goes with original battery.
Now want prepare myself for replacement but there actually nothing.
I bought OWON like scopemeter with signal generator with 20000 count multimeter and ..
this thing sas slooooow... Waiting with calendar to get reading.

Gave it to friend

Can anybody give suggestion for replacement ?
I paid like 300 eur plus VAT , now they are on sale in EU approximately 350 to 500 eur.
Nice features will be USB C port for connection , replaceable 18650 batteries..
May be I am dreaming.

Also: I bought Peaktek 3440 which is also CEM made. and this is not so precise or sensitive for PWM voltages measurement!
9989 show 10 volt and Peaktech 3440 which is only multimeter, show 7 volts.
And 10 is more like it was!!! Resistance meter also have 0,000 resolution on CEM DT9989 compare to 0,00 on CEM DT-989/Peaktech3440

Thank You!

Andrus

tunk · « **Reply #21 on:** March 16, 2025, 11:19:25 pm »

Maybe Owon HDS242, or Zoyi ZT-702S or ZT-703S?
There's many others (not quite updated list):
https://www.eevblog.com/forum/testgear/portable-oscilloscopes-list/

dzwer · « **Reply #22 on:** March 17, 2025, 10:55:42 am »

Some comparison of CEM DT-9979 with Fluke 289: https://drive.google.com/drive/folders/1igp7XqN7p45zGInvfhaxH3LSriLjsxmb
I had the CEM just for the comparison, but was impressed 🙂
I have the Fluke on my work place.
My own DMM is UNI-T UT161E: https://meters.uni-trend.com/product/ut161-series/#Specifications
The letter "E" is the important one!

coromonadalix · « **Reply #23 on:** March 17, 2025, 10:59:59 am »

i think joeqsmith has done some torture on the meter ??, you can still check some teardowns ...

ru_tash · « **Reply #24 on:** March 17, 2025, 12:41:42 pm »

I am using DT9918T and I noticed unwanted behavior on DC or Resistance measurements, which is that the last digit jumps around the average value in 2-3 points.
Is there any way to fix this?
this is more noticeable near the end of the scale (ex 34.56V->34.54V->34.58V and so on in a circle)

Andrus · « **Reply #25 on:** March 17, 2025, 06:25:59 pm »

Hello!

I looked everything and looks like I was lucky with mu CEM DT9989.

But looks like there is no actual competitor.

Those newer model OWON and Hantek are soo slow at multimeter side


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Author Topic: Multimeters and portable digital oscilloscope from CEM Instruments (Read 12798 times)

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