Brymen BM869s suddenly weird behaviour - Page 1
Forum section: electronics / testgear

author: prutser
author_rank: Regular Contributor
timestamp: March 13, 2022, 10:13:42 am
content: I have a Brymen BM869s, which I bought 2nd hand and already used quite some time without problems. At this moment it starts to behave weird.- Auto ranging does not work most of the time. (Now applying 9.6V DC and it is continuesly blinking (no digits), same happens when measuring 230V AC.- DC voltage readings are unstable, measuring un unloaded battery shows voltage jumping around 1.4V (+/- a few 100mV).- At this moment, measuring a 9.6V power supply with manual range: Brymen shows an unstable 3.1V, reversing the polarity (negative) shows a lower value and still unstable.So in general my BNM869s suddenly became wacko, I did not abuse it as far as I know. The only thing I did not check yet, is the battery voltage, but I assume it has an empty battery indicator.Anyone seen this kind of behaviour ?

author: AVGresponding
author_rank: Super Contributor
timestamp: March 13, 2022, 10:32:14 am
content: I'd check the battery as a first port of call even if there's no low battery warning coming on. After that I'd check the leads and sockets for contamination, you'll have to take the case apart to do this thoroughly.

author: prutser
author_rank: Regular Contributor
timestamp: March 13, 2022, 01:50:40 pm
content: Thanks for the reply, checked the battery, while still connected it measured 8.5V which is not full, but also not really empty. Replaced it it with a new battery, unfortunately no improvement.Lead contacts seem also no problem (meter is hardly used and looks new as well)It's a pity, except my 2nd hand Fluke45, this is my most expensive multimeter in more than 40 years. Brymen reviews were quite good, but now I had to revert to my 30yr old Metex. It seems more reliable.I do not know if I just have bad luck, but I am reluctant to buy a Brymen again. Schematics are not available, so troubleshooting is not easy.

author: AVGresponding
author_rank: Super Contributor
timestamp: March 13, 2022, 02:54:02 pm
content: Let's consider a hypothetical situation: Someone spills coffee on your meter. Instead of telling you, they clean it up, quite thoroughly on the outside, but because they do not understand DMMs they do not clean the sockets beyond stuffing some tissue down them to get the bulk out.You come along later, and now the coffee residue inside the meter causes you to get odd readings.Unless you open it up and eyeball the board around the sockets, you're not going to know if this is a good or a bad guess...

author: Avelino Sampaio
author_rank: Frequent Contributor
timestamp: March 13, 2022, 03:50:25 pm
content: HiContact Joe Smith. I hope he can give you some good tips.

author: prutser
author_rank: Regular Contributor
timestamp: March 15, 2022, 07:25:59 pm
content: Thanks for the reply. Coffne on the meter definately didn't happen. Just a home lab, no kids, I do not drink coffee here and my wife avoids the placeThe meter looks brand new, both from the outside and from the inside as well. DC current reading looks ok. I measured the voltage inside the meter (after the sockets) voltage is rock solid. On the Vin pin there are a couple of large series resistors followed by some surge protectors. Voltage measured here is also rock solid.

author: adam4521
author_rank: Regular Contributor
timestamp: March 15, 2022, 10:18:46 pm
content: I had very similar symptoms develop on my secondhand Fluke 87v, which I'd had for several years. It was one of the test leads -- internally frayed cable near the joint to the probe. Still working, but volts reading was fluctuating exactly as you have described. I pumped 10A through the test leads, it got hot at the bad joint.

author: LDDM
author_rank: Contributor
timestamp: July 12, 2024, 01:56:37 pm
content: This is an old topic but i have the same issue with 2x BM869s. Did you ever found a solution or at least the problem?Please see:https://www.eevblog.com/forum/testgear/bm869s-not-reading-correct-voltage/