Brymen BM2257 - No autoranging in mV AC - Page 1
Forum section: electronics / testgear

author: thejackal
author_rank: Newbie
timestamp: August 28, 2025, 08:11:30 pm
content: Hi everyone,I bought a BM2257 and I found what I think is a firmware fault/bug.The mVAC function (in mV-Freq-Temp) does not have autorange as the mVDC does.It defaults to the 600mV range and you have to choose the 60mV range manually.In the manual you see (page 9) that mVAC should default to AUTO as the mVDC does.Holding the range button down (long-press) to set it in auto-mode doesn't help either.The firmware version of this one is 2503 (hold the REL button when the meter is turned on).Are all the BM2257's like this or only some firmware versions?And (maybe a matter of opinion), how important is this in practice?I suppose we should expect this kind of quirks in new meters.And if we don't want that, we have to go with something that has been around for a while, like the BM857 or BM859, and miss some very handy functions like auto-hold and diode beep.Regards,Carlos

author: danno_cj
author_rank: Contributor
timestamp: August 28, 2025, 09:50:19 pm
content: The newest BM786 and BM789 have auto-hold and diode beep but have a bigger size compared with BM2257.

author: geralds
author_rank: Contributor
timestamp: August 28, 2025, 11:29:15 pm
content: Quote from: thejackal on August 28, 2025, 08:11:30 pmI have just checked my BM2257, also FW 2503: same behaviour. I would expect Auto-range as shown in the manual. I will email Brymen.eu from which I purchased mine.Seprately, is it correct that BeepJack (wrong input alert) will not be triggered (i.e. no beep) if A/mA or uA is selected and test lead is connected to V etc Input instead of A or mA/uA Input?Thanks for bringing this to my attention!

author: J-R
author_rank: Super Contributor
timestamp: August 29, 2025, 03:30:04 am
content: Same and same here. Also on the few YouTube reviews I watched.Early adoption does have these risks.Or maybe it's on purpose and Brymen will just update their manual.

author: thejackal
author_rank: Newbie
timestamp: August 29, 2025, 09:22:42 am
content: Quote from: geralds on August 28, 2025, 11:29:15 pmI also purchased mine at Bruymen.eu. I would like to hear about how your contact with them goes.Quote from: geralds on August 28, 2025, 11:29:15 pmThat is correct. There is no danger in 'measuring' current connected to the V input (high impedance). Nothing will happen.But the other way around, 'measuring' voltage connected to the A or mA/uA input (very low impedance, a short) will blow your fuse or cause more damage to the meter and whatever you are measuring.As an aside, the input alert will also be triggered when uA is selected with the test lead in the A jack. Which is good!Here is another quirk:I 'm geting a beep and sometimes a backlight flash randomly when changing functions and arriving at the 'Ohms-Cont.-Diode-Cap.' function.I found one way to reproduce it:1 disable beeps (hold the range button pressed when turning on the meter),2 select some function other than current,3 insert a lead in the A or mA/uA jack (you see the "InEr" message) and remove it again (no beep, of course!),4 select the 'Omhs-Cont.-Diode-Cap' function.The meter will beep, sometimes with a backlight flash!That is one way to reproduce it, but I'm sure it happens also in other ways.I also am disappointed with the enable/disable beep behavior.What is the point of beeping each time a button is pressed? None, as far as I'm concerned.Okay, I can disable it. But then the Rec, Crest and Auto-Hold will not beep anymore when reaching a min., max. or stable value. :-(Regards