Brymen BM235 Meter Issue - Page 1
Forum section: electronics / testgear

author: Charles01
author_rank: Newbie
timestamp: February 23, 2025, 08:26:07 pm
content: I'm experiencing issues with my BM235 where the meter will power on, but the screen will not show "zeroes" and just the decimal point. The "header" icons at the top of the screen ("Auto", symbol for measurement mode, etc.) appear normal and the buttons under the screen work to change measurement settings properly.With no inputs (no leads attached) and in all measurement modes except resistance measuring, the display shows only the decimal point. In resistance mode, "OL" shows.Example of "no zeroes" showing and just the lonely decimal point on the screen below:However, when there is an input to the leads in voltage mode or mV mode (1.5V AAA battery, or included thermocouple leads), the screen shows 1 or 2 backwards "L"s to the right of the decimal point. The backwards "L"s disappear once the input is removed and the screen goes back to only displaying the decimal point. For the resistance measurement function, the "OL" changes to backwards "L"s when the test leads are shorted together and returns to "OL" after the leads are separated again. Interestingly, when changing the resistance mode to continuity check, the alarm sounds and the screen lights up indicating the meter detects the shorted leads. This makes me think that something is up with some aspect of the display (the screen itself, or maybe the responsible IC(s)) since the input is being detected, but not displayed properly.I bought the BM235 from Dave about 3-4 years ago. Since then, I've used it a handful of times for low-voltage (<30V) DC voltage, current, and resistance measurements with good results. I noticed the issue after not using the meter for about 0.5-1 year. I always stored it out on my bench (finished living space: temperature and relatively humidity controlled environment) or in a hard-shell zippered case underneath my bench. At first, I thought the display issue was just due to dead batteries, but then manyyyy changes of battery sets later, the issue persisted.I've watched a few of Dave's videos diagnosing issues with the BM235: none of the videos that I saw had similar symptoms as my meter. I did open up my meter to follow along with the videos and did not find any of the internal issues Dave identified in those cases.Any help/suggestions are appreciated!

author: Phaseseeker
author_rank: Regular Contributor
timestamp: February 23, 2025, 08:40:59 pm
content: On mine it tends to do weird stuff like that when the rotary selector is an "invalid" position, for instance when it's in a position between two modes. Maybe try checking if all contacts are properly touching on the PCB.

author: EEVblog
author_rank: Unknown
timestamp: February 23, 2025, 10:52:58 pm
content: Haven't heard of that issue before.Apart from checking the range switch contacts, my best guess would be failure of main processor (possibly due to bit rot or similar), one of the main failure modes of Brymen meters.Fairly rare, but happens enough for it to be a known issue. Doesn't just happen on the BM235, but most Brymen meters that use the same processor series.

author: Charles01
author_rank: Newbie
timestamp: February 26, 2025, 12:38:55 am
content: Thanks for the reply! I do have a distinct “- - -“ show on the screen when intentionally holding the switch in the “in between” positions. So I think my switch is working OK.