Products > Test Equipment
Brymen BM789
J-R:
I have a 78905.
1) I can reproduce the diode issue if I turn the DMM on, go straight to that mode and short the leads right away.
2) Low battery behavior is a complex issue IMHO, especially when you consider the discharge curves of various chemistries and how they act under load. Then throw the backlight into the mix and it's a bit of a minefield for detection. But on the flip side, in normal use the backlight will probably cause the low battery indicator to come on first, so that may be the most consistent indicator.
3) Yes, I have had the issue with the Brymen selector switch ending up between positions. Some years ago my BM235 did that very badly when I turned it off and somehow ended up between Off and AutoV. I put it away for a while and some weeks later the plastic had malformed and the switch literally flopped in the breeze. I reversed the process over another few weeks and that fixed it.
Since then, I have been taking apart my Brymen DMMs and adding a small amount of lubricant to specific areas of the selector switch mechanism. I also add a tiny amount of precision lube to the contacts on the PCB. Between the two, the selector feels a lot nicer to me, but maybe that is personal preference. Due to the short warranty and overseas shipping costs, I consider all my Brymen DMMs to be disposable.
If you just purchased your BM789, it might already have firmware 11. What version is yours? (Turn on while holding â–².)
sonpul:
1. A 0.5 second interruption occurs in BeepLitâ„¢ Diode Alert operation. I work with the device daily and intensively. If you had not paid attention to this moment, I would not have noticed it.
2. I use 3xAAA Panasonic Eneloop Pro batteries, BM789 lasts a very long time with them. The battery icon is present when measuring V~ and mV dBm. The measurements are accurate, but I'm just heeding this nutritional warning. Maybe in these truerms modes, the nominal voltage is desirable for the converter.
3. I can create a beep by switching between diode continuity and temperature. But in thousands of measurements, I have not set the switch in this position.
BM789 is so good and convenient that you stop paying attention to these "shortcomings"
mwb1100:
(I don't have a BM789 but a BM786)
--- Quote from: giosif on April 23, 2023, 05:55:02 pm ---2. Low battery indicator - as per the video, the threshold for this is different for the different functions.
For example, I did some measurements and, when in ACV measurement mode, the threshold for displaying low battery is approx. 3.76V.
At the same time, the threshold for displaying low battery when in DCV mode is 3.58V.
Is this intended, I wonder (i.e. Brymen feel confident the meter will display accurate DCV readings even with lower battery levels?)?
--- End quote ---
It would not occur to me that a low battery indicator showing in some modes but not others when the battery is at the edge of a low voltage condition would be considered a problem unless readings were wrong.
--- Quote from: giosif on April 23, 2023, 05:55:02 pm ---3. Rotary selection switch - in my brief time spent with the meter (got it only a few days back), it already happened that I wanted to switch to Diode mode and, without connecting the probes to anything, the meter starting beeping as when measuring a short.
When I looked a bit more carefully, I noticed the rotary switch had ended up between functions (namely, between Capacitor/Diode and Temp).
--- End quote ---
I can't recall ever landing between settings. But if you believe this might happen again more than once in a a blue moon (or once in a lifetime), then you might want to consider an exchange or different meter. I'd guess that landing between positions accidentally was a fluke though. But there has been selector oddness discussed before (things like pressing on the selector would cause the meter to misbehave, and if I remember right, Dave did a video diagnosing a BM786 problem that turned out to be a defect on the the selector's PCB contact area). I believe those problems were one-off defects rather than problems with the BM78x design.
Neutrion:
1.
FW version 08 here. The beeplit has this short pre-beep also but not with a one second brake, but rather maybe a tenth of a second. And yes sometimes it doesn't prebeep, but I never noticed this when working with it. You want to keep the probes connected to have a good contact and to read a stable value so I think this is not an issue.
2. See explanation from J-R! Some mode draws more power, so the battery goes suddenly to a lower voltage. Happens only when the battery is getting close to the treshold level. The exact value depends on the battery type, and temperature.
3. The Brymens switch is rather too stiff to get it accidentaly betwen position. Now I tried it, it is indeed possible, but you really have to try it hard.
I would suggest to Brymen to actually make the switch be much lighter, it would feel better when not working in heavy gloves.
2N3055:
--- Quote from: J-R on April 23, 2023, 10:40:03 pm ---
3) Yes, I have had the issue with the Brymen selector switch ending up between positions. Some years ago my BM235 did that very badly when I turned it off and somehow ended up between Off and AutoV. I put it away for a while and some weeks later the plastic had malformed and the switch literally flopped in the breeze. I reversed the process over another few weeks and that fixed it.
Since then, I have been taking apart my Brymen DMMs and adding a small amount of lubricant to specific areas of the selector switch mechanism. I also add a tiny amount of precision lube to the contacts on the PCB. Between the two, the selector feels a lot nicer to me, but maybe that is personal preference. Due to the short warranty and overseas shipping costs, I consider all my Brymen DMMs to be disposable.
--- End quote ---
I have BM525S and BM869S and you simply cannot put them between the positions, it snaps very positively into predefined positions...
I think your opinion is very judgmental, based on sample of one. I'm not saying it did not happen to you, but one is not a sample to make conclusions on. I have no experience with other models, though.
Also, shipping and such is a USA problem. In EU they are readily available and affordable.
Here Fluke is more expensive than in USA.
Price difference between new F87 and BM869S (that is feature vise closer to F287 minus the graph mode) is such that you can buy 2-3 BM869S here... That takes care of potential warranty issues. And in last few years I had BMs, they are going strong...
I consider them very good quality and excellent alternative to super expensive Fluke so far.
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