BM869S not reading correct voltage

[BeBuLamar]

Can you send it to manufacturer for repair at reasonable cost?

[robert.rozee]

So I did a few tests to see, please see the table below [...]

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]

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.

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]

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?

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.

[LDDM]

The BM869s is actually pretty well sealed.  There are gaskets/o-rings around the battery cover and the banana jacks, even the screw heads.  So I don't think humidity would impact it.

But you could still fully inspect the PCB under a microscope looking for any solder issues or corrosion, clean selector switch and jack contacts.

A side note is that each jack's BeepJack feature does not function if their respective fuse is blown, so double-check those.

What 9V batteries are you using?

Yes, like you said, it is very well sealed, with o-rings at the jack, battery, and all around the shell as well. I would love to check it with a microscope, but I need to buy one.

I will order one and see if I can find something, but by looking at the board closely, I did not notice anything unusual. By the way, any recommendations for a cheap USB or HDMI microscope?

Yes, I have checked the fuses on both meters, and they are all okay.

I was using a Duracell Plus (6LR61) in the first meter and a Varta (6LP3146, long life Alkaline) in the second meter. Yesterday, I bought a cheap brand (PKCell 6LR61 long life "Ultra" alkaline ) to try and see if it makes any difference.

Unfortunately, no difference at all.

[LDDM]

Can you send it to manufacturer for repair at reasonable cost?

I did not check what it would cost yet, i have to ask local post, DHL and Fedex.

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   :-)

I only tested resistance of the lead with the multimeter itself (which seems good), they were my only multimeters seens i bought them, so i have to buy a new one / borrow to check. However, is tested with my PSU lead witch are good.

[J-R]

For sure an odd situation, still feels like we're missing something...

But maybe Brymen got a bad batch of a component.  You could e-mail them with the serial numbers and see if they come back with any help.

Some other random thoughts:
- enter calibration mode and note the display in different switch positions, but don't actually calibrate it (https://www.jackenhack.com/calibrating-brymen-bm-series-multimeter/)
   (on my BM869s, I get 2.50000 for VFD and VAC, 0.00000 for VDC, 000.000 for mVDC, 250.000 for mVAC, 0000.0C for T1/T2, 000.00 for capacitance, 250.000 for resistance, 50.0000 for A/mA and 500.000 for uA.)
- connect maybe around 1VDC to the input and using another DMM, follow that 1V input as far as you can on the PCB to see where it goes
- also with the same 1VDC, bypass the obvious parts of the COM & V input protection and see if there is a difference
- power the DMM with a DC supply (carefully!!!) and note the power draw, or, are the 9V batteries still full after using them with the DMM for a bit?

[LDDM]

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.

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.

So, if the failure I'm seeing is related to this, there is little to zero chance that it could be fixed, right? Unless I can get a working processor and the matching firmware.

I would love to send one of them to Dave if he wants to have a look at it. I even have a family member going to Australia next week, so it would be cheap to get it there.

I will investigate and see if I can find the issue, but I have to buy a new meter first!

[LDDM]

For sure an odd situation, still feels like we're missing something...

But maybe Brymen got a bad batch of a component.  You could e-mail them with the serial numbers and see if they come back with any help.

Some other random thoughts:
- enter calibration mode and note the display in different switch positions, but don't actually calibrate it (https://www.jackenhack.com/calibrating-brymen-bm-series-multimeter/)
   (on my BM869s, I get 2.50000 for VFD and VAC, 0.00000 for VDC, 000.000 for mVDC, 250.000 for mVAC, 0000.0C for T1/T2, 000.00 for capacitance, 250.000 for resistance, 50.0000 for A/mA and 500.000 for uA.)
- connect maybe around 1VDC to the input and using another DMM, follow that 1V input as far as you can on the PCB to see where it goes
- also with the same 1VDC, bypass the obvious parts of the COM & V input protection and see if there is a difference
- power the DMM with a DC supply (carefully!!!) and note the power draw, or, are the 9V batteries still full after using them with the DMM for a bit?

Just checked the serial numbers, and they could be from the same batch: MFR.#: xxxxxx240 and xxxxxx185 (all "x" are the same).

Regarding the values in calibration mode, I also have the same on both meters (VFD: 2.50000, VAC: 2.50000, VDC: 0.00000, mVDC: 000.000, mVAC: 250.000, T1/T2: 000.0C, Diode/Cap: 000.00nF, Resistance: 250.000, A/mA: 50.0000, and uA: 500.000).

I powered the meter with my RD6006P at 9.1V, and it drew 0.0038A with a peak at 0.0051A, depending on the mode.

For the other tests, I will buy a multimeter locally (might be a Uni-T for now) and revert back.

[BeBuLamar]

I don't think it's bad leads. Bad leads generally cause bad reading in resistance but not voltage.

[Fungus]

I think it's time for Dave to dig out his original Brymens and give them a workout.

He's been threatening to do it for ages... 

[Fungus]

First post here. Some time ago, I bought a BM869s after watching some videos of EEVblog on YouTube.

How long ago, exactly?

[LDDM]

First post here. Some time ago, I bought a BM869s after watching some videos of EEVblog on YouTube.

How long ago, exactly?

So I received the first one (with the leaking battery) in the first week of May 2021, and the replacement meter sometime later. I don't really remember if it was in May or two months later, as I was not in the country and received the first one just before leaving.

[Fungus]

So I received the first one (with the leaking battery) in the first week of May 2021

So only 3 years old.

[floobydust]

Does Brymen even issue RMA's for off-warranty goods? I'm not sure they do repairs.

OP, the high cost to ship it back to Taiwan, customs paperwork, insurance, your time - just toss these in the garbage and buy something new.
With no schematic or IC datasheets, troubleshooting is difficult, and there are known quality issues, as with any product.

There is a safety issue with a multimeter that "fails to give an accurate voltage reading, resulting in the operator falsely believing the electrical power is off or low. This poses an electrocution hazard."
If this malfunction is due to a Brymen defect then a product recall would be in order and the 61010 certificate would get revoked for the models affected.

[BeBuLamar]

Does Brymen even issue RMA's for off-warranty goods? I'm not sure they do repairs.

OP, the high cost to ship it back to Taiwan, customs paperwork, insurance, your time - just toss these in the garbage and buy something new.
With no schematic or IC datasheets, troubleshooting is difficult, and there are known quality issues, as with any product.

There is a safety issue with a multimeter that "fails to give an accurate voltage reading, resulting in the operator falsely believing the electrical power is off or low. This poses an electrocution hazard."
If this malfunction is due to a Brymen defect then a product recall would be in order and the 61010 certificate would get revoked for the models affected.

So you meant if you live outside of Taiwan which I believe most of us do then after the warranty period there is no service for the Brymen?

[Fungus]

So you meant if you live outside of Taiwan which I believe most of us do then after the warranty period there is no service for the Brymen?

Brymen works through resellers so it probably depends on where you live.

Brymen Europe has a service option listed on their web site but I don't know the pricing for diagnosing/repairing/calibrating a non-working BM869s. It might not be economical, these aren't Fluke price levels or profit margins.

[floobydust]

Does Brymen even issue RMA's for off-warranty goods? I'm not sure they do repairs.

OP, the high cost to ship it back to Taiwan, customs paperwork, insurance, your time - just toss these in the garbage and buy something new.
With no schematic or IC datasheets, troubleshooting is difficult, and there are known quality issues, as with any product.

There is a safety issue with a multimeter that "fails to give an accurate voltage reading, resulting in the operator falsely believing the electrical power is off or low. This poses an electrocution hazard."
If this malfunction is due to a Brymen defect then a product recall would be in order and the 61010 certificate would get revoked for the models affected.

So you meant if you live outside of Taiwan which I believe most of us do then after the warranty period there is no service for the Brymen?

North America - yes, they are locked out. OP's Mauritius I have no idea.
There is no mention on any website of dealers, distributors, repair/cal centers which adds to the mess. As soon as you need to ship it anywhere, major expense.

They should be sent to Brymen TW for an autopsy, see if they need to issue a recall.

[LDDM]

Sent an email to the only email i could find on Brymen.com (info@brymen.com)

Check everywhere could not find any support email. If someone know the support email for Brymen Taiwan, would greatly appreciate if you could share it.

I will update this post if i get any reply.

[joeqsmith]

That's all I ever used. 

[radiolistener]

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.

In my case the leads was never stretched and it was stored in ideal home conditions (about 20-25°C and and dry air, no moistures and chemicals in the room), I used them very carefully and wiped the gold needles with cotton wool and 95% ethyl alcohol.

But my new golden plated Brymen leads, just out of the box, was about 0.09Ω which is twice worse than these Chinese leads which is about 0.04Ω. And my Brymen gold plated leads going worse and worse with time despite the rare and careful usage.

Now they are lying with no usage in the box, because I use Chinese leads. Periodically, just out of curiosity, I check the Brymen leads and they show a stable high resistance degradation over time. Their current resistance is about 10Ω...

I'm almost sure these leads was developed with some hi-technology which allows to get so bad resistance degradation over time, because I never seen such effect on any kind of leads. So, I think they using some kind of nano-technology materials which allows to get so high and quick resistance degradation, probably in order to make leads unusable after 1 year, so the user will go to shop to buy a new replacement... Why I think that they using some kind of hi-tech nano-technology? Just because I can’t even imagine how it’s possible to deliberately make probes with such degradation over time effect...

But thanks to Chinese guys, they make cheap leads which has a little worse initial resistance, but their resistance is very stable and don't change over time...


Regarding to the Brymen DMM itself, it works. But it has high sensitivity to a static electricity, there was some strange effect when I peel the protection film from the display - when I put my hand near display, it leads to DC voltage spike and LCD segments flashing. This effect was very high when I tried to put a plastic pencil near display. LCD segments was flashing even when DMM was powered off. Probably some issue with shielding and plastic material properties. After years, it still has static electricity effect, but now it is a little bit less visible (maybe because I'm used to it).

[radiolistener]

Sent an email to the only email i could find on Brymen.com (info@brymen.com)

Check everywhere could not find any support email. If someone know the support email for Brymen Taiwan, would greatly appreciate if you could share it.

I will update this post if i get any reply.

I contacted with Brymen using info@brymen.com, but they can't help with leads issue, they propose to ask help from seller, so if you bought it on internet shop which don't have after sale warranty, then there is no warranty at all...

[floobydust]

[...]
Regarding to the Brymen DMM itself, it works. But it has high sensitivity to a static electricity, there was some strange effect when I peel the protection film from the display - when I put my hand near display, it leads to DC voltage spike and LCD segments flashing. This effect was very high when I tried to put a plastic pencil near display. LCD segments was flashing even when DMM was powered off. Probably some issue with shielding and plastic material properties. After years, it still has static electricity effect, but now it is a little bit less visible (maybe because I'm used to it).

What are you talking about, 80% humidity tropical environment has pretty much nothing for ESD. Activating LCD segments with static charge takes a very high level electric field and the multimeter must be connected to something big, not just sitting there by itself.
Your bench might have a problem. Laminate flooring is the worst or that composite wood benchtop in the pic.
It's normal the DCV jumps around when handling any multimeter. "Segments flashing" I have no idea what that looks like, is that the bar graph? They can only flicker due to being floating i.e. driver IC output is not working, as in the multimeter is powered off or maybe a firmware error does not properly turn off annunciators/segments but that's something that can be tested.

High humidity causes oxidation and corrosion, I would suspect the rotary switch or interconnects (headers).

I think a question at hand is if Brymen TW offer any support - repair, cal, parts etc. after warranty.

[radiolistener]

Activating LCD segments with static charge takes a very high level electric field and the multimeter must be connected to something big, not just sitting there by itself.
Your bench might have a problem.

This is not bench, this is Brymen DMM issue. It very sensitive to static electricity, due to properties of DMM case plastic materials. It works like electric machine, producing static electricity when you touch transparent plastic window over Brymen DMM display... You can touch it with finger, in that case you can even feel static electricity on transparent plastic window surface and its discharge to finger leads to LCD segments flashing. Other equipment don't have such effect, only Brymen DMM. And it has this electrostatic effect in different rooms and different environment conditions. Just touch DMM display and you can see it's DC measurement spikes...

I think this issue is present only on BM867 model, because it don't have shielding as BM869