Author Topic: EEVBlog branded Brymen BM235 in depth feature review and thoughts (Read 24222 times)

Scottjd · « **on:** February 21, 2016, 11:37:22 am »

I know this is a long video but I really did test everything except the diode tester. Somehow I forgot about that. Being my first Brymen I'm impressed with the acuracy even down to the mV and uA.

If you want to cut to the chase then the beginning is my thoughts. The middle is all testing, the end is a neat design feature I missed until I was cleaning up and my final thoughts over all. I don't normally review DMM's but being my first Brymen I thought I would run it through the ringer and fully test it. So I decided to video it also.

FYI, I think I found the chase of the backlight noise also. I'll update once I'm done looking into it.
UPDATE: This is the post with the tear down.
https://www.eevblog.com/forum/testgear/quick-tear-down-of-the-eevblog-brymen-bm235-backlight-noise-research/

https://youtu.be/sfXiTFebXlU

Fungus · « **Reply #1 on:** February 21, 2016, 12:02:01 pm »

"Wringer". You put things through the "wringer"...

This is a wringer:

This is a ringer:

Brumby · « **Reply #2 on:** February 21, 2016, 12:14:18 pm »

... when auto correct won't help you, someone will always notice.

HAL-42b · « **Reply #3 on:** February 21, 2016, 12:17:33 pm »

I didn't know about the blinky continuity feature. Nice!

My only problem is that contrary to Dave I don't really like latched continuity. Most of the time I'm using that for checking worn cables with intermittent connection. For that application the cheap non-latched buzzer is best. You connect your leads and bend the cables and listen for the scratches. If the buzzer is latching type you can't do that.

EEVblog · « **Reply #4 on:** February 21, 2016, 12:19:57 pm »

Cool, first review, thanks.

Bob F. · « **Reply #5 on:** February 21, 2016, 12:44:07 pm »

"Wringer" is correct... To put though harsh and excessive punishment or interrogation.

nctnico · « **Reply #6 on:** February 21, 2016, 12:56:31 pm »

Quote from: HAL-42b on February 21, 2016, 12:17:33 pm

Most of the time I'm using that for checking worn cables with intermittent connection. For that application the cheap non-latched buzzer is best. You connect your leads and bend the cables and listen for the scratches. If the buzzer is latching type you can't do that.

I agree. Sometimes I have to do some reverse engineering and have to figure out which signal goes where on several chips with hundred pins or more each. Instant continuity test allows to drag the probe along the pins quickly and test hundreds of connections in seconds.

Wytnucls · « **Reply #7 on:** February 21, 2016, 01:43:58 pm »

Transients below 100mS become difficult to hear. For instance, at 10mS, a 15dB sound pressure increase is necessary to detect a click at the same loudness as a 1 sec beep.
A properly implemented latching continuity tester will circumvent this adverse effect.
The Fluke 87V and 289 will pick up a transient of 1mS. The Fluke 179, 250uS.

Ref: Master Handbook of Acoustics

HAL-42b · « **Reply #8 on:** February 21, 2016, 02:02:35 pm »

I'm not listening for the beep. I have a continuous beep and I'm listening to an interruption or a scratch. If I hear a scratching noise while I'm wiggling the cable I know I have connection problems.

So I'm listening for a dis-continuity, the exact thing a latching buzzer is trying to mask.

nctnico · « **Reply #9 on:** February 21, 2016, 02:10:26 pm »

Quote from: Wytnucls on February 21, 2016, 01:43:58 pm

Transients below 100mS become difficult to hear. For instance, at 10mS, a 15dB sound pressure increase is necessary to detect a click at the same loudness as a 1 sec beep.
A properly implemented latching continuity tester will circumvent this adverse effect.

By that time I'll be 100 pins further. If the beep is difficult to hear I go slower over the pins to make the tone last longer; simple as that!

Scottjd · « **Reply #10 on:** February 21, 2016, 02:39:40 pm »

Quote from: EEVblog on February 21, 2016, 12:19:57 pm

Cool, first review, thanks.

Your Welcome, it was fun to do.
I needed to test out that process calibrator also. So I was able to get two things done in one shot.

lpc32 · « **Reply #11 on:** February 21, 2016, 03:01:29 pm »

Aren't there meters with toggleable latching?

Wytnucls · « **Reply #12 on:** February 21, 2016, 04:02:14 pm »

If the two surrounding sounds are the same (spectra, duration), the auditory gap detection threshold (GDT) is 2-3mS. It increases to 20mS otherwise.
Manufacturers don't specify in their datasheets if their multimeters can detect such a gap in a constant short circuit. It should be easy to find out, with the right equipment.

(Hearing: An Introduction to Psychological and Physiological Acoustics
By Stanley A. Gelfand)

https://books.google.mu/books?id=ZlnvBQAAQBAJ

Wytnucls · « **Reply #13 on:** February 21, 2016, 05:02:47 pm »

As an example, this simulation of an intermittent connection (2-5mS) is detected by the Fluke 185 (latched continuity <1mS) as a single event, with a single beep interruption:
(The Uni-T UT-71 series, with its notoriously slow latched continuity, doesn't detect this intermittent connection)

HAL-42b · « **Reply #14 on:** February 21, 2016, 05:22:57 pm »

Quote from: Wytnucls on February 21, 2016, 05:02:47 pm

As an example, this simulation of an intermittent connection (2-5mS) is detected by the Fluke 185 has a single event, with a single beep interruption (latched):

Interesting. I wonder what the book says about tone acuity. If I was trying to improve the buzzer that would be the area I'd look into. Resistance controlled oscillator sensitive to 0-20 Ohms.

We've completely hijacked the thread though, better take this to another thread.

Scottjd · « **Reply #15 on:** February 21, 2016, 05:24:17 pm »

As I mentioned in the main post. This is the update for the thread to the tear down video.
https://www.eevblog.com/forum/testgear/quick-tear-down-of-the-eevblog-brymen-bm235-backlight-noise-research/

Scottjd · « **Reply #16 on:** February 21, 2016, 05:27:47 pm »

Quote from: HAL-42b on February 21, 2016, 05:22:57 pm

Quote from: Wytnucls on February 21, 2016, 05:02:47 pm
As an example, this simulation of an intermittent connection (2-5mS) is detected by the Fluke 185 has a single event, with a single beep interruption (latched):

Interesting. I wonder what the book says about tone acuity. If I was trying to improve the buzzer that would be the area I'd look into. Resistance controlled oscillator sensitive to 0-20 Ohms.

We've completely hijacked the thread though, better take this to another thread.

LOL, it's not like anyone is replying to my post. Their just watching the video. At least your hijacking keeps the thread at the top for others to see.

Wytnucls · « **Reply #17 on:** February 21, 2016, 05:29:56 pm »

Quote from: HAL-42b on February 21, 2016, 05:22:57 pm

Quote from: Wytnucls on February 21, 2016, 05:02:47 pm
As an example, this simulation of an intermittent connection (2-5mS) is detected by the Fluke 185 has a single event, with a single beep interruption (latched):

Interesting. I wonder what the book says about tone acuity. If I was trying to improve the buzzer that would be the area I'd look into. Resistance controlled oscillator sensitive to 0-20 Ohms.

We've completely hijacked the thread though, better take this to another thread.

Well, this is still relevant to the latched continuity of the Brymen 235. Tone acuity is supposedly better as the frequency increases.

boggis the cat · « **Reply #18 on:** February 23, 2016, 02:09:45 am »

Just got the BM235 I ordered from Dave and it had a rattle. In my experience that doesn't bode well.

Turns out it is a small jumper that was loose inside. The only jumper pins present are labelled "J1". Should these have a jumper in place, or did I get a free bonus from Brymen?

I also noticed that there is a position on the main board for a LED that seems to be aligned with the comms port (holes are present in the rear case). I might check if there is any signal present across there, presuming it to be for a data send option.

MarvinTheMartian · « **Reply #19 on:** February 23, 2016, 03:36:27 am »

Quote from: boggis the cat on February 23, 2016, 02:09:45 am

Just got the BM235 I ordered from Dave and it had a rattle. In my experience that doesn't bode well.

Turns out it is a small jumper that was loose inside. The only jumper pins present are labelled "J1". Should these have a jumper in place, or did I get a free bonus from Brymen?

Just cracked mine open - small plastic base on the jumper pins but no jumper in place. You've scored yourself a spare jumper.

No idea what the jumper is for though

Scottjd · « **Reply #20 on:** February 23, 2016, 04:34:47 am »

Quote from: boggis the cat on February 23, 2016, 02:09:45 am

Just got the BM235 I ordered from Dave and it had a rattle. In my experience that doesn't bode well.

Turns out it is a small jumper that was loose inside. The only jumper pins present are labelled "J1". Should these have a jumper in place, or did I get a free bonus from Brymen?

I also noticed that there is a position on the main board for a LED that seems to be aligned with the comms port (holes are present in the rear case). I might check if there is any signal present across there, presuming it to be for a data send option.

I've already done a tear down, that jumper on J1 should be empty.
So keep the jumper and call it a bonus.

boggis the cat · « **Reply #21 on:** February 23, 2016, 05:02:16 am »

Quote from: Scottjd on February 23, 2016, 04:34:47 am

I've already done a tear down, that jumper on J1 should be empty.
So keep the jumper and call it a bonus.

OK, thanks.

My guess is that 'J1' would be for calibration adjustment, but I'm not too keen on experimenting and discovering that is does something else, like zeroing out the calibration data.

crispy_tofu · « **Reply #22 on:** February 23, 2016, 06:19:15 am »

Thanks for the review!

MarvinTheMartian · « **Reply #23 on:** February 23, 2016, 09:29:17 am »

Does anyone actually know what the J1 jumper if for?

Johnny Electron · « **Reply #24 on:** February 28, 2016, 02:45:26 pm »

Very well done review! Thanks for that!


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Author Topic: EEVBlog branded Brymen BM235 in depth feature review and thoughts (Read 24222 times)

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