EEVblog 1520 - Troubleshooting a Faulty BM786 Multimeter

[McBryce]

Hi Dave,
        this is a very off-topic question, but possibly an important one for many... Why do you have a large poster of a very questionable public figure displayed behind you? Or am I mistaking who that is? If that is who I think it is, I consider it very distasteful.

McBryce.

[thm_w]

So the micro was dead but also another IC? What could cause this? Overvoltage on 3.3V rail? Maybe the user tried hooking something up to the programming port and maybe used 5V instead of 3.3?
Will we get a part 3 where you go further?

Unlikely user would have tried to program it.
No other ICs were proven dead yet, youtube comments noted possibly low battery could cause that error.

But the actual cause, who knows, could be ESD (dave didn't think so), or that rework job was wrong, or firmware corrupting to an unrecoverable state.

Hi Dave,
        this is a very off-topic question, but possibly an important one for many... Why do you have a large poster of a very questionable public figure displayed behind you? Or am I mistaking who that is? If that is who I think it is, I consider it very distasteful.

McBryce.

Why not be more specific, that guy in a red and green christmas suit?
Chances are most people don't care.

[bob808]

If just that micro died than it can clearly be a random thing. Not worth pursuing further.

[McBryce]

So the micro was dead but also another IC? What could cause this? Overvoltage on 3.3V rail? Maybe the user tried hooking something up to the programming port and maybe used 5V instead of 3.3?
Will we get a part 3 where you go further?

Unlikely user would have tried to program it.
No other ICs were proven dead yet, youtube comments noted possibly low battery could cause that error.

But the actual cause, who knows, could be ESD (dave didn't think so), or that rework job was wrong, or firmware corrupting to an unrecoverable state.

Hi Dave,
        this is a very off-topic question, but possibly an important one for many... Why do you have a large poster of a very questionable public figure displayed behind you? Or am I mistaking who that is? If that is who I think it is, I consider it very distasteful.

McBryce.

Why not be more specific, that guy in a red and green christmas suit?
Chances are most people don't care.

It seems to be a picture of ex-Prince Andrew.

McBryce.

[EEVblog]

Hi Dave,
        this is a very off-topic question, but possibly an important one for many... Why do you have a large poster of a very questionable public figure displayed behind you? Or am I mistaking who that is? If that is who I think it is, I consider it very distasteful.
McBryce.

I have no idea who he is, I found it in the dumpster and it's a joke with my live audience and twitter users who follow me when I found him in the dumpster.
I presume it's some local businessman in my business. We call him Larry.
Who do you think it is?

https://twitter.com/eevblog/status/1526911165657681921

[EEVblog]

But the actual cause, who knows, could be ESD (dave didn't think so), or that rework job was wrong, or firmware corrupting to an unrecoverable state.

Extremely unlikely to be ESD in a previously working meter that was not taken apart. It simply just failed one day.

[EEVblog]

Will we get a part 3 where you go further?

Probably not, unless I find something.
Someone mentioned battery voltage, I'll double check that when I can, but I don't think it's it.

[McBryce]

Hi Dave,
        this is a very off-topic question, but possibly an important one for many... Why do you have a large poster of a very questionable public figure displayed behind you? Or am I mistaking who that is? If that is who I think it is, I consider it very distasteful.
McBryce.

I have no idea who he is, I found it in the dumpster and it's a joke with my live audience and twitter users who follow me when I found him in the dumpster.
I presume it's some local businessman in my business. We call him Larry.
Who do you think it is?

https://twitter.com/eevblog/status/1526911165657681921

Maybe it's just because the picture is so small (as you are in a sub-window), but it looks very like Prince Andrew from here.

McBryce.

[EEVblog]

Maybe it's just because the picture is so small (as you are in a sub-window), but it looks very like Prince Andrew from here.

Thousands of people have seen it, you are the first one to even suggest that.

[McBryce]

Maybe it's just because the picture is so small (as you are in a sub-window), but it looks very like Prince Andrew from here.

Thousands of people have seen it, you are the first one to even suggest that.

Face recognition was never my strong point Maybe it's just because I recently watched a documentary about him?

McBryce.

[IanJ]

Will we get a part 3 where you go further?

Probably not, unless I find something.
Someone mentioned battery voltage, I'll double check that when I can, but I don't think it's it.

3.1Vdc is the power up cut-off on my BM786. Still powers up fine.
Anything below that it doesn't power up at all (nothing on the LCD).

Ian.

[joeqsmith]

Unlikely user would have tried to program it.

I wouldn't put it past a beginner to play with that programing connector and fuck up their meter in doing so.   

[Neutrion]

Is it possible to decap the chip properly to have a picture and see what went wrong? I am not aware of many troubleshooting videos about the inside world of a microcircuit. (OK have never looked for one) It would be interesting. We would finally also have a REAL teardown picture of our loved Brymen meters brain.
In the design phase of chips it must be done, so people are possibly doing it. Maybe it would be a nice video as well. Once I saw a video about a german company producing the testers to test single transistors on the highest end processors.
And if we are here, once I posted a question on this board what could cause the mass failures of Linkswitch LNK chips and the likes, but everyone was just guessing. However it causes huge amount of electric failures.
I think there is no single other component in electronic history which alone caused so much trouble.

 

[EEVblog]

Unlikely user would have tried to program it.

I wouldn't put it past a beginner to play with that programing connector and fuck up their meter in doing so.

Possible, but from my communication with the owner it seems unlikely.
And there is a history of BM235 chips just failing.

[IanJ]

Unlikely user would have tried to program it.

I wouldn't put it past a beginner to play with that programing connector and fuck up their meter in doing so.

Possible, but from my communication with the owner it seems unlikely.
And there is a history of BM235 chips just failing.

I've had two customer instances over the years where the Atmel uP just plain failed (PDVS2mini). Both times it powered down ok at last use, but the next day it just failed to power up completely (running on batteries only).
I half think that maybe at power up or power down the 3.3Vdc regulator "fails" and maybe spikes through a higher voltage killing the uP.

Ian.

[Neutrion]

Unlikely user would have tried to program it.

I wouldn't put it past a beginner to play with that programing connector and fuck up their meter in doing so.

Possible, but from my communication with the owner it seems unlikely.
And there is a history of BM235 chips just failing.

The frontend, or the hy2613? Only a given batch is affected, or all of them? Is it known what is the process size used in these?
Isn' it extreme rare that a chip fails without overvoltage? Sorry for the many questions!
Because the frontend could get some spikes which get through, but the processor should be a bit more separated I suppose.

[EEVblog]

The frontend, or the hy2613? Only a given batch is affected, or all of them? Is it known what is the process size used in these?
Isn' it extreme rare that a chip fails without overvoltage? Sorry for the many questions!
Because the frontend could get some spikes which get through, but the processor should be a bit more separated I suppose.

The processor. Doesn't seem to be batch related. It's not many but there is a history of it.

[bob808]

I found this in its manual:

Beep-Jack™ Input Warning
The meter beeps as well as displays “InEr” to warn the user against possible damage
to the meter due to improper connections to the A, mA, or A input jacks when another
function, especially a voltage function, is selected.

[EEVblog]

I found this in its manual:

Beep-Jack™ Input Warning
The meter beeps as well as displays “InEr” to warn the user against possible damage
to the meter due to improper connections to the A, mA, or A input jacks when another
function, especially a voltage function, is selected.

Yep, but it doesn't go away when the amps range is selected, so it's something else at fault.

[Kleinstein]

There is an report of the inEr occuring after water damage. So this could be thing with leakage or possibly a solder bridge / solder ball causing a short.

[SeanB]

IC failure is often from ESD damage at some early point, as it can take months to show up, even years, so it is insidious. Could be as simple as a broken ground lead on one of the PNP machines, but the ball races still provide a good enough path for discharge normally, only the odd chip gets zapped. Otherwise could be a die defect where a trace is just too small, and electromigration eventually makes it open.

Water ingress and conductive paths causing Iner is also common, it can take a lot of washing to remove the contamination from the board and sockets.

[Neutrion]

That's interesting, thanks! If you would happen to have any good links to this topic I could apperciate it.
As far as I know also older (bigger) technology could be also more reliable if done properly.
As for the ball races: I would supose, that in such enviroments already conductive grease is used.

[bob808]

Could the "InEr" error come from a bad ADC chip?

[EEVblog]

There is an report of the inEr occuring after water damage. So this could be thing with leakage or possibly a solder bridge / solder ball causing a short.

In that case though the warning should stil go away when in the Amp range switch position.

[Jeeper44]

Around the 2:54 mark in the second video, 1522, you mention a content creator who has multi-series troubleshooting videos. Can you share that name again. I've tried searching based on what I think you said but haven't found them. This was right after mentioning Joe Smith.