Products > Test Equipment
BM869S not reading correct voltage
BeBuLamar:
Can you send it to manufacturer for repair at reasonable cost?
robert.rozee:
--- Quote from: LDDM on July 12, 2024, 07:16:11 am ---So I did a few tests to see, please see the table below [...]
--- End quote ---
have you checked the meter leads using a known-good multimeter? this meter may be even the cheapest "dm830" giveaway from harbour freight.
from your results i'm rather suspicious that all your leads have been 'stretched'; when a multistranded cable is stretched it is possible for every strand to be broken, but each in a different location down the length of the cable. the result is that while the cable may appear to have end-to-end continuity at first, over time as oxidization occurs due to moisture ingress the cable becomes highly unreliable. it could well be that the sheathing Bryman uses happens to be particularly susceptible to moisture ingress in high humidity environments.
the risk of stretching cables is why meter leads should never be wrapped tightly around the instrument, or in any other way subjected to force along their length. good leads are made of multiple very fine strands to provide for flexibility, and those fine strands are more susceptible to breakage than heaver ones.
cheers,
rob :-)
J-R:
He did say he tried different leads: https://www.eevblog.com/forum/testgear/bm869s-not-reading-correct-voltage/msg5570587/#msg5570587
mqsaharan:
--- Quote from: LDDM on July 12, 2024, 07:16:11 am ---How can something like this happen? What would it take to break a meter like this?
(Note: No blown fuses, no burned components in the meter.)
Moreover, I replaced both 9V batteries this morning and tested the test leads / used banana test leads from my PSU with no luck.
--- End quote ---
If all else is all right, I mean, if there is no problem with the support circuitry of the processor(s), it could be (analog front end) processor die rot. As Dave once said and I quote "One of the failure modes seem to be related to some sort of processor die rot."
https://www.eevblog.com/forum/testgear/brymen-bm789-360289/msg5042728/#msg5042728
And in his next message (in the same thread,) he said that Brymen uses well known brand but he cannot disclose because of NDA.
I think it is Fortune Semiconductors. For some of their meters, they might be using custom chips but I doubt it will be the case with all their products.
I don't own any Brymen meters. I might have tried to trace the circuitry to figure out the chip they are using.
LDDM:
--- Quote from: joeqsmith on July 12, 2024, 05:00:45 pm ---Sadly as you have seen, seldom people who post about their problems ever provide a conclusion.
I live near fresh water and it's not a problem like other parts of the USA. I've never had to consider conformal coating. Do you have to store your electronics in special containers or is not a problem where you live? Is the humidity always high enough that ESD isn't a concern?
--- End quote ---
Yes, I also noticed that there is no conclusion, but I found a post on Reddit, and the author responded to my comment. He had the exact same issue I have, so he sent it to Brimen, and they could not figure out the issue. They advised sending it to Taiwan (which was too expensive), so he just bought a Fluke.
See his post here: https://www.reddit.com/r/AskElectronics/comments/lcembb/comment/lcu67bw/?context=3
If I remember correctly, at the start I also only had issues with AC voltage but did not investigate as I did not have time. But now, as stated, nothing works except continuity and small resistor tests (but I don't know for how long...).
Regarding ESD, to be totally honest, I'm relatively new to "advanced electronics" (although I've been tinkering for quite some time now and designing really simple PCBs for hobby projects), and I do not have the right gear. I need to invest in some mats and a static wrist strap, I think.
Where I live, the average humidity in winter (dry season) is 80% to 86%, and it regularly reaches 92% during the day.
Usually, I do not have issues with electronics. No issues with 3D printer main boards, computer parts, Raspberry Pis (although the Wi-Fi chip metal shield always rusts...), or anything else.
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