BRYMEN BM789 vs. BENNING MM 12 (APPA 506B) comparison - interested? - Page 1
Forum section: electronics / testgear

author: Cymaphore
author_rank: Regular Contributor
timestamp: June 02, 2021, 01:43:35 pm
content: Hi,I recently got a BRYMEN BM789 and could do a comparison against my existing BENNING MM 12 (APPA 506B). If anyone here is interested I can also compare it against the RS PRO S2 (APPA S2).I could do some performance comparision, precision comparison, or whatever might be of interest.Both meters are vanillia, the only thing I did - to both meters - is greasing the rotary using electrolube CG70 for the contacts and traces, and Äronix silicone grease for the plastic parts). The MM12 is in heavy use for a longer time but generally in mint condition and it has a well-known stable calibration status.Anyone interested?Best regards,Martin

author: coromonadalix
author_rank: Super Contributor
timestamp: June 02, 2021, 05:12:25 pm
content: Would love to see the guts of a 789 ...

author: Cymaphore
author_rank: Regular Contributor
timestamp: June 02, 2021, 06:20:00 pm
content: Teardown #1

author: Cymaphore
author_rank: Regular Contributor
timestamp: June 02, 2021, 06:23:21 pm
content: Teardown #2I didn't desolder the shieldingStill got the device open on my bench, just let me know if a detail is missing.And I didn't remove the rotary-cover to not ruin my glorious greasing. :-) ... If you absolutely want it I will remove it, but I rather not screw arround with the plastics to often.

author: pjwum
author_rank: Contributor
timestamp: June 02, 2021, 10:01:02 pm
content: Hi Martin,a comparison would be great. Especially because Bennings/ Appas don't show up too often on this forum.I owned a Benning 7-1 for some time. Extremely responsive meter, very fast autoranging and measurement speed. I expect the MM12 to be similarly superior to the Brymen. Feature-wise the meters are very different, also regarding their pricepoints.What is your impression about the BM789's speed and overall responsiveness? I would be interested in your real-life experience beyond the datasheets.Patrick

author: Crambone
author_rank: Frequent Contributor
timestamp: June 02, 2021, 10:32:01 pm
content: I use a Bremen and would like to see the comparison.Andrew

author: Cymaphore
author_rank: Regular Contributor
timestamp: June 02, 2021, 11:48:44 pm
content: Happy to do that, I hope it is not too unstructured, it's based on my preliminary experience.See also my Review of the MM12 here:https://www.eevblog.com/forum/testgear/benning-mm-12-(appa-506b)-my-experience-(with-pictures)/msg3507808/#msg3507808For context: I'm in electrical engineering with focus in testing (traction batteries, testing, vehicles, occasional electronics) and have usually a different focus on measurement equipment.Reference test25°C ambient, Stabilized for >1hAD584JH voltage reference:Nominal | BM789 | MM122.5V | 2.4980 | 2.49795.0V | 5.0000 | 5.0007.5V | 7.499 | 7.49910.0V | 10.001 | 10.001Precision resistors:Nominal | BM789 | MM12100 | 100.04 | 100.021k | 1.0004k |1.0011k10k | 10.000k | 9.996k100k | 100.06k |100.02kDisplay and BargraphWith a sample rate of 10/s for most functions the MM12 is one of the fastest hand held meters available on the market. However, the bargraph is updated at the same rate, that's where the BM789 is the clear winner. It's bargraph is remarkably quick, actually I don't know if I know anything better.Display light and viewing angel the MM12 is superior. The BM789 has the brighter display backlight, but viewing from top angel is fading away. The "warm white" Brymen backlight versus the "cool blue/white" APPA backlight is a matter of taste, I personally prefer the latter since I usually have only neutral or daylight white light at workspaces anyways. Both displays are very good to read. MM12 is also better in artificial light situations.MM12 can be configured: Automatic backlight based on ambient sensor, always on, always off. BM789 at least has a long lasting backlight in contrast to other useless quick-off backlights, but cannot be turned on permanently.The MM12 has dual display for many of it’s functions like the BM869s, I consider this very useful but not a strict requirement.Display strategy is completely different on both meters, because the MM12 has something like a menu with arrow button navigation in contrast to the button-only function switching of the BM789. Matter of personal preferences here as well, both approaches work well.Rotary switch and function setupAfter some intense greasing the rotary of the BM789 has a much better in handling than out of the box. However, the MM12 can be operated single-handed completely by thumb, the required area underneath the rotary is free for that purpose. The BM789 is hard to operate by thumb, almost impossible with insulation gloves on (have to use the other hand in that case) and the test jacks are in the way when doing so.MM12 has a setup menu and deterministic strategy (always defaults to configured settings) in contrast to the BM789 remembering anything and allowing some pre-sets by power on keypress. It's a matter of taste, I think.RuggednessThe MM12 is much more robust and rugged, the casing including the booth is significantly thicker - but also significantly more heavy. My impression is, that the BM789 is very robust, but you cannot “hammer a nail in the wall” with it like with the MM12. On the other hand, holding it for a longer period of time is more convenient with a light meter like the BM789.The MM12 has a magnetic holder included, for the BM789 it is available as an extra. The magnet of the BM789 is really strong and grabs everything it can. When oriented one way it even dimms the beeper, like many people already observed. The other way around it is not a problem. When mounted on the back, the meter can directly be put on metal surfaces just like the APPA S Series and P Series meters (like my RS PRO S2) with the it’s magnetic booth. I like that very much and prefer it over the MM12s magnetic hanger. In vehicle or cabinet, I use this regularly to place the meter safely since I usually don’t have a convenient surface to place a meter.Tilt stand of the MM12 is more robust and made out of a soft material similar to the booth. Tilt stand of the BM789 is harder and more suited for permanent bench usage and has less grip on the surface. Both tilt stands work well and stable.Both meters are well suited for field use. However, the automatic backlight and rugged design of the MM12 is superior, while the BM789 has a slot for the magnet (as seen on the picture of the back, in the “right”/non-faulty orientation that doesn’t block the buzzer).Safety and electrical robustnessBoth meters have all the required components, protective circuits and design features to fulfill the standards and ratings. From what I’ve seen in Joe Smiths videos the Brymen is probably a bit better, but not by much.I used the MM12 in developing with a test system at 200kW for a 800V traction battery (together with a Fluke and a GMC unit) and it performed well, however fortunately I never made a capital mistake – yet, fingers crossed – that would require these circuits to do their job.Battery and fuse replacementMM12: One screw to access the battery and all fuses, no case opening required.BM789: Two screws to replace the battery, eight to replace the fuses, with PCB exposed in the process. Removing the fuses can be difficult, since there is no good nearby surface to push them out safely.Battery life of the BM789 is by the numbers better than that of the MM12. Both meters work well with NiMH cells.Voltage DCThe MM12 has a significantly faster display of voltage readings. At 10/s it's actually one of the fastest available handheld meters on the market. It shows readings and DC ranges faster than most other handheld meters I know of.However, the bargraph is updated at 10/s as well, that's where the BM789 is clearly significantly better.In my tests, the reading of both meters (MM12 in 40k mode) matches usually exactly or by 2 digits. The MM12 has an up to date calibration with certificate.Crest mode / peak hold works pretty much alike, no big difference between both meters (within tolerance).Auto hold works the same way on both meters as well.MM12 has a 40mV-range without equivalent on the BM789.BM789 (like in most aspects) is more precise by spec, in my humble tests the readings were mostly equal.AC+DC present and as far as I can tell working equally well on both devices.The MM12 has an intentional quick “rolling down” effect to accelerate the display reading after ranging, that is an unusual and unique feature and can be useful but irritating when facing it for the first time.Voltage ACBoth meters are about the same. MM12 has dual display and shows frequency and voltage. MM12 is again overall faster. Crest mode / peak hold works pretty much alike, no big difference between both meters (within tolerance). MM12 has a 40mV-range without equivalent on the BM789.Resistance, Diode, etc.BM789 ranges faster and reads a bit more accurate than the MM12. For smaller values it’s about equal. Continuity is vastly superior to the MM12 and fantastic to use.Diode tester is better on the BM789 as well, higher output voltage and beep for good Si-Diodes, but it takes a bit longer for the value to settle.BM789 can read conductance, MM12 doesn't have that feature.CapacitanceBoth meters get about the same readings and are about equally quick for the smaller ranges. Hovever, towards the mF-Ranges the BM789 is significantly (factor of two) faster than the MM12.TemperatureBM789 has two temperature inputs, MM12 only one. BM789 is much less thermally insulated than the MM12. That is good, if you want to balance the device with ambient conditions, but quite bad, if you need to shortly change location to a very hot or cold place, where the MM12 stays stable for a longer time due to it's thick outer casing.With the same sensor and stabilized conditions both meters give the same (+/-0.3°C) readings for room temperature. Both meters measure equally quick.Frequency and duty cycleBM789 has a better frequency counter, it's configurable and supports duty cycle. MM12 has a better sample rate and is even useful for some hifi amp poking.NCVBM789 has the stupid EF-feature that - like all other devices having that gimmick - detects harmless low volt output of switched supplies as dangerous voltage and deems some of my insulated HV-supplys harmless. Don't use that, don't trust it. General issue with “non contact voltage detection”, not Brymen-specific. The MM12 lacks that safety hazard.I’m not fundamentally against it, I value that feature as an add on on my two pole voltage tester to identify active circuits when cables are unlabeled, but I would never trust it for what it is usually marketed for.And I personally know no one who used that feature in a DMM to actually locate a breaking point in a wire. But someone here can proof me wrong.CurrentBoth meters work about equally well for A and mA ranges, the MM12 is once again faster but the BM789 has a very nice and well working µA range. The MM12 is more precise in measuring inrush peaks, however both meters are quite good at that.The BM789 can do 4-20mA level, the MM12 can’t do that.The 40mA ranges of the MM12 are an advantage with current transducers, but other than that the BM789 plays well with the eqipment I already have.Other than thatThe MM12 is a different class of meters, more like the 869s, but since it's my favorite meter I took it for comparison. Beside the things mentioned already, it has Bluetooth, optical USB, Datalogging, Remote Display via Smartphone App and a couple of other nice things I like about it.I wrote a sigrok-driver for the MM12 that I regularly use for logging and math using the cli and SmuView (usually together with the RS PRO S2 via Bluetooth LE). So I have a better insight into the MM12 than into my brand new BM789. I hope that Brymen will one day make something like a BM789 + Bluetooth LE for remote display reading and pc connectivity.ConclusionHappy to have them both, good complements. Now my personal DMM trio (BENNING MM 12, BRYMEN BM789, RS PRO S2) is finally complete, with each meter having it’s individual strengths and advantages.Only the poor little DT-830B disagrees with that statement by 12 digits (depending on the moon phase and it’s horoscope).

author: joeqsmith
author_rank: Super Contributor
timestamp: June 02, 2021, 11:57:52 pm
content: Quote from: Cymaphore on June 02, 2021, 11:48:44 pmThis is based on your expert opinion, or you actually have data that shows where the Benning and Brymen both fail using some common standard? Have you cycled the greased up switches to failure? Dropped them? Anything? Maybe they just look good to you?

author: Cymaphore
author_rank: Regular Contributor
timestamp: June 03, 2021, 12:23:00 am
content: Quote from: joeqsmith on June 02, 2021, 11:57:52 pmFor the MM 12 I actually tried to understand how what is protected out of interest. If I understood it correctly is another story. For the 789 I could point to your extensive work on the 786 and don't distrust the claims on the meter fulfilling the standards.Don't get me wrong. This is my personal experience and opinion based on that, not results of repeatable testing and number crunshing. I only have some basic knowledge here and not your expertise or equipment regarding meter testing.The rotary is strictly a matter about how it feels when I use it, not the lifecycle. I grease it to be able to optimally one-thumb it without breaking my finger or overshooting. If the the CG70 has some theoretic additional advantages on life time and spark prevention, fine for me.Ruggedness: It's my gut feeling. A friend of mine uses a MM 12 that was rolled over by a testing vehicle and has only a couple of scratches. Maybe that gave me some over confidence and in actual testing the outcome would be different. My MM 12 falls down occasionally on metal and other grounds, no problems or damages so far. The case design of the BM789 just feels like much less material to catch the forces to me, so maybe I misjudged that. Sorry in that case.

author: joeqsmith
author_rank: Super Contributor
timestamp: June 03, 2021, 01:47:03 am
content: Quote from: Cymaphore on June 03, 2021, 12:23:00 amThis makes much more sense.

author: EEVblog
author_rank: Unknown
timestamp: June 03, 2021, 02:28:25 am
content: Quote from: Cymaphore on June 02, 2021, 11:48:44 pmThat was actually the plan upon release, to have a BT option. But they had delays in the development so released it without BT. I don't know the current status of it.I tried to get them to activate the serial output from the main chip so people could add their own BT module, but they didn't come through on that

author: Cymaphore
author_rank: Regular Contributor
timestamp: June 03, 2021, 06:25:00 am
content: Quote from: EEVblog on June 03, 2021, 02:28:25 amIt got to my mind that I could easily fit a CC2541 in the empty space under the display, even without the risk of compromising the voltage rating, because nothing is nearby.But with these ASICs, little chance of finding out the serial connection. However, the ugly solution of just putting the LCD output on BLE is easily possible, because the driver is nicely accessable.Also, my gut feeling is that that there is SPI connection somewhere on U4 pin 1-12, that could be reverse engineered and fed to a CC2541 or similar.However, if they plan something like that, I rather wait for the clean solution. Might be nice to buy it with your branding.By the way is it just my unit or does the whole 78x Series have a relatively weak viewing angel from the top with backlight on (a bit like on many of the flukes I have available at work)?

author: joeqsmith
author_rank: Super Contributor
timestamp: June 03, 2021, 11:32:26 am
content: I would guess that APPA is the OEM. I've never ran any of their products and have no thoughts of how it may hold up. Looking at your photos, it appears they use the series PTCs rather then having the typical surge rated resistor. They don't appear to be the piss ant 5mm package that we have seen blow apart. I do see some what appears to be some nicks in the PCT. Sadly, there is no picture showing what the inside of the top case half looks like.http://www.appatech.com/en/It looks like the non-B version is available for about $230 USD w/tax and shipping. I changed one of the ICs on the BM789 that Brymen sent to improve some of my concerns that were identified during my testing. This may have reduced the meters performance. From Dave's 786 thread, it looks like they may have released new firmware. Other than running some harmless functional tests on the 789, it should be fine. I plan to review it at some point. Maybe we could run them side by side and collect some data on them.

author: Cymaphore
author_rank: Regular Contributor
timestamp: June 03, 2021, 03:28:18 pm
content: Quote from: joeqsmith on June 03, 2021, 11:32:26 amThis image is a good example. I'm wondering if R147 and R146 of the MM12 will have the same kind of pulse energy characteristics and withstand voltage like the comparably big shunts of the BM789. I've observed that components with better dielectric and pulse characteristics are usually bigger, R40 of the BM789 has much more volume, that's why my gut feeling tells me it should survive your tests longer than the MM 12 in case of a pulse that can not be handled adequitly by the diode network & co.Originally I didn't take photos of that area because the display light is soldered on. Later on I was interested in the MCU of the device and removed it anyways. Display light is a soldered-in pcb, I actually broke one of the legs of the LED supply because I was not careful enough when it stuck in the hole on removal. Luckily that was easy to fix. Attached is an image of the area underneath the display and images of the DMM and ADC chipsets.I would be glad to assist in that! What would be the requirements and what would I need in preparation / eqipment to deliver adequit data?

author: joeqsmith
author_rank: Super Contributor
timestamp: June 03, 2021, 03:48:54 pm
content: Quote from: Cymaphore on June 03, 2021, 03:28:18 pmThese are current shunts which have little to do with any of the potential destructive tests I run. About the only thing I will do with the current inputs is pull the fuses and check they don't breakdown. If they ship with a non-safety rated fuse, I may light them up.Most of my tests evolve around the voltage inputs, not the current. It's the only metric I track. I have been known to life cycle the switches, drop them and dab them with various chemicals but I don't keep records of that in the spread sheet.Could you post a picture of the inside of the top half case (function switch) where those PTC sit. Is there something there that caused the damage to your meter?

author: Cymaphore
author_rank: Regular Contributor
timestamp: June 03, 2021, 04:46:13 pm
content: Quote from: joeqsmith on June 03, 2021, 03:48:54 pmGood question, I was already using it for some time when I took the pictures. I'll have a look if it's possible I hit it with the tip of a screw (I left the screws in the holes when I checked how good the case slides in). Or I accidentially hit it with the sharp probe tip when I traced the functions. I'll open it up later on and investigate before I continue to speculate my head off.Otherwise only one relevant event regarding the V-Input comes to mind before I did the teardown: I accidentially measured a 465VDC measurement point of a terminal with the meter still in continuity. The meter didn't show any sign of malfunction afterwards, I did a brief check on the functions to see if it caused any damage.

author: Cymaphore
author_rank: Regular Contributor
timestamp: June 03, 2021, 10:54:23 pm
content: Here are further detailed images from the MM12.The BM789 just won a promotion to prime meter on the home bench for the time being. I left the MM12 open in a box for further investigation (it can be operated for as long as the rotary switch screw is in, see last image.PTC103Looks like I touched it with the soldering iron when removing the display, what a shame. Burn mark, also on the shrinking tube. In-Circuit readings of those PTCs range from 1.25k to 1.27k. First closeup is before I cleaned it.R107 (Shunt)Found with more detailed visual inspection on the components. Looks interesting and did not change noticeably over the last 8 months.Interesting that the amp-readings are always good on the meter with a component that looks like this.I hope I cought all the angels that you asked for. Btw, thanks for your expertise on this.

author: Cymaphore
author_rank: Regular Contributor
timestamp: June 03, 2021, 10:56:11 pm
content: MM12: Rest of the detail images.

author: Cymaphore
author_rank: Regular Contributor
timestamp: June 04, 2021, 06:13:54 am
content: Quote from: Cymaphore on June 03, 2021, 10:54:23 pmTo correct myself:Probably is came like that, since I had not yet desoldered the display at the time the first images were made. There was nothing (active) nearby on the bench as far as I remember, that could cause something like thisDue to pollen allergy and the medication against it my head is currently a bit worn out.

author: Cymaphore
author_rank: Regular Contributor
timestamp: June 04, 2021, 07:00:35 am
content: Regarding the viewing angle of the BM789, Part 1:First Image: How I look at it on the desk, ambient light is a neutral white LED light.Set of images: Cloudy morning, different viewing angels, looking in from outside the window

author: Cymaphore
author_rank: Regular Contributor
timestamp: June 04, 2021, 07:06:37 am
content: Regarding the viewing angle of the BM789, Part 2:Set of images: Backlight on, otherwise "complete" darkness

author: Cymaphore
author_rank: Regular Contributor
timestamp: June 04, 2021, 07:17:57 am
content: One additional shot, because I could not always get it to focus the digits correctly, because of the reflections. Daylight from the right

author: Cymaphore
author_rank: Regular Contributor
timestamp: June 05, 2021, 04:24:07 pm
content: Quote from: joeqsmith on June 03, 2021, 03:48:54 pmOn the BENNING MM12: I further inspected it but didn't find any other significant issues, but my knowledge is rather limited. Still I'm unsure why the shunt looks like that, I put a lot of Ah by the A input even before the first images, but nothing that surpasses the I²t rate of the fuse or the rating of the meter, so it should not be an issue.What would be your opinion overall about that, and the quality of the input protection of the MM12 in general?

author: joeqsmith
author_rank: Super Contributor
timestamp: June 05, 2021, 10:42:01 pm
content: Quote from: Cymaphore on June 05, 2021, 04:24:07 pmIt seems you do not know the difference between the shunts and the PTCs. Odd as I had circled the parts with a line pointing to the damage. I've also explained I don't collect any metrics on the current inputs.As for the voltage input, it's hard to say how well it would hold up. Normally I just test them and collect the data and will leave the opinions to the experts. I have ran other meters that used what appears to be a similar clamping technique with series PTSs. The wouldn't suggest your meter would behave the same. The only way to know it to run it to failure and see where it stacks up.

author: Cymaphore
author_rank: Regular Contributor
timestamp: June 06, 2021, 08:32:02 am
content: Quote from: joeqsmith on June 05, 2021, 10:42:01 pmI made some close ups in this post here:https://www.eevblog.com/forum/testgear/brymen-bm789-vs-benning-mm-12-(appa-506b)-comparison-interested/msg3581849/#msg3581849On the PTCs as well as the Shunt and some close ups in the input protection overall

author: joeqsmith
author_rank: Super Contributor
timestamp: June 06, 2021, 02:45:50 pm
content: Quote from: Cymaphore on June 06, 2021, 08:32:02 amEven if I had the meter in front of my, I lack the skill to be able to look at a product and determine how well it will perform. I'm a bit jealous as most reviewers do seem to posses this skill where I have to design and construct transient generators and actually test them to know how they will perform. A typically expert reviewer can provide an answer to how robust a meter is in seconds. It takes me about a day.One of the more interesting handheld meters I looked at was the UNI-T UT181A. It appears they used some decent parts in that meter. They appeared to use a fairly common clamp design. Still as a result of a poor layout the one I bought was damaged prematurely.

author: Cymaphore
author_rank: Regular Contributor
timestamp: June 06, 2021, 03:59:51 pm
content: Quote from: joeqsmith on June 06, 2021, 02:45:50 pmI fully agree.Probably I should be more careful about judging it only on a theoretic basis (components present and percieved to be of the correct size, percieved as being connected correctly and gaps are fine, brand). But my judgement was also based on long time usage experience. Not significant regarding it's extreme limits, you're right about that. Also the device survived the moron using it so far pretty well, for what it's worth.I was just interested in an assessment based on what's visible out of interest and to maybe get a better understanding.

author: joeqsmith
author_rank: Super Contributor
timestamp: June 06, 2021, 05:51:40 pm
content: If I owned a $2.00 meter and it sat in a box without batteries for 20 years, would you be impressed if I told you that my cheap meter lasted 20 years?If that same meter was only ever used to test 1.5V batteries and it never blew the front end, then I said it was in constant use for 20 years and was never damaged, would you be impressed?There is a member here who reviews meters who commented after I damaged a Keysight by rotating the switch a few thousand cycles. I showed how the switch was made with a glass filled plastic and broke all the springs. He explained how they rotate their switches 10's of thousands of cycles each year with no failure and made some half hour rebuttal video to tell us that. Not one test was ran, and they couldn't even pull the meter apart to show if their spring was made from the same materials. All they had was their expert opinion.I attempt to test them to some sort of common standards and then document my findings. My motives in running these tests are out of my own interest. There's no Patreon account and no begging for people to like and subscribe. I've been called a fan boy from time to time, most of what I will comment on is based on the data I've collected.

author: Cymaphore
author_rank: Regular Contributor
timestamp: June 14, 2021, 03:52:35 pm
content: Just for fun and out of interest I made a video to compare the bargraph and display reading speed (recorded in 60p) while "measuring" "music":Quote

author: Cymaphore
author_rank: Regular Contributor
timestamp: August 02, 2021, 08:53:05 am
content: In myvideo about the SIEMENS B1023I did two measurements using the BM789. In case someone is not interested in my whole blabla and love about the vintage meter, I put here two direct links to the timecode of the two tests involving the BM789 (first the SIEMENS, then the BRYMEN).At 14:04:Measurement of a Photoresistor, to demonstrate how fast autoranging in resistance range is by waving my hand over the sensorAt 20:17:Measurement of an automatic colorchanging RGB-LEDto demonstrate the performance in diode mode