Fluke 87V screen goes crazy with WIFI & Cell phone signals

[NiHaoMike]

My Mastech MS8226T used to glitch if I connected it to a circuit with a rather high dV/dt (an unfiltered inverter, for instance) but it stopped doing that after I took it apart to clean the dial switch. I suspect there was a dirty connection that caused a control signal to drift near a threshold and made it particularly sensitive to noise. (I'm thinking about putting dielectric grease on the contacts next time I clean it, but I'm concerned if it could affect its accuracy.) It has not "broke" from this but I'm not surprised since the microcontroller is probably an OTP part. Not sure why you would need to upgrade firmware on a simple multimeter anyways.

I suspect yours was defective (bad shielding or filters) since there would otherwise be lots of broken meters from amateur radio experimenters.

[Twistx77]

Hi Folkes,

Sorry for my absence but I've been very busy since I'm going on a trip for a month.  I was going to send a video of it, but now that I've seen what happened to Kiriakos (Sorry about that) I don't think I'll keep trying.

The first time it happened to me, I don't know if the phone was in 3G or GSM mode since it wasn't mine. The second time was in GSM so I wouldn't dare to try with 3G ... Maybe Dave would?

Luckily I didn't get the error and it seems to be working just fine for now. I hope it stays that way.

By the way mine is the original Fluke version.

[Kiriakos-GR]

[Kiriakos-GR]

So we have one case of interference by WiFi, and another of bricking by mobile phone. This doesn't sound like a 1-off.

Dave.

I believe that and in the first case, the mobile phone was responsible.
The WiFi has an output of few mW .... the mobile phone has an output of 0.4 - 0.8 Watt ..

So the mobile phone looks stronger , but still  its ridicules as event.

Who will ever believe that if you throw an aspirin over a train , the train will get out of the rails !!    

I offer my sympathies to you guys! This really sucks and now that Kiriakos has a bricked 87V it's hard not to believe it.

I would hope that Fluke addresses the issue. I can certainly imagine situations where you have your meter on at work, get a phone call, put it on speaker and hold the phone near the meter, or lay the meter and your phone on a counter or bench and talk to someone while taking readings. If a simple GSM signal from a phone can brick a really expensive meter, someone didn't do their testing thoroughly enough. If it's not specific to GSM, would a walkie talkie do the same thing (strong signal burst)?

Totally agree ..

And the point are that even if I get from Fluke an positive up come , an working DMM , what I will had to do ??  babysitting it for life ?  

Just tested and the rest gang .... the killer mobile phone did not effect them ..

[PetrosA]

If they fix it, just wrap it in aluminium foil to keep it safe from cell phones AND aliens.

[Kiriakos-GR]

a video review on this should be done. to warn everybody and to open Fluke's eyes (or hopefully pant )

Well this issue worth's an international recall of any Fluke 87-5 ( return to base ) , for adding in it " extra shields " and inspection .

And speaking about video review , I like to see how the similar Metrawatt DMM  stands against the same risk.
An active  mobile phone standing next to it , 1-2 centimeters next to it (at any direction of the case) and faceplate , will be very reviling .

 

[Kiriakos-GR]

If they fix it, just wrap it in aluminium foil to keep it safe from cell phones AND aliens.

Its not that simple PetrosA , any addition as shield , it could work as shielding , but its possible to compromise the behavior of the DMM ( safety against transients ) .

And so ....  Its not that simple..  

[jahonen]

And speaking about video review , I like to see how the similar Metrawatt DMM  stands against the same risk.
An active  mobile phone standing next to it , 1-2 centimeters next to it (at any direction of the case) and faceplate , will be very reviling .

Tried this on my new Metrahit Energy. While no permanent change was done, the nearfield RF clearly affected the measurement results, something that one would expect. Here is a record of measurement values while I exposed the meter to the GSM phone. I also increased the transmitter activity by rubbing the microphone so that it has to transmit the resulting noise. Readings returned quite fast to normal just as I moved the phone away from the meter. This was easy to do since I have the IR cable for the meter. Just turned the "send" function on.

Also, tried it on my Fluke 89 IV. It beeped once (couldn't repeat this even after several tries), but reading remained quite stable. Also no permanent change to the DMM. Unfortunately, no logged graph here, I don't have IR cable for this one.

Regards,
Janne

[jahonen]

And, isn't it strange coincidence that US FCC EMC testing does not require immunity testing, only emissions must be controlled and Fluke is US based company . However, manual states that RF fields up to 3 V/m should not even cause deviation from specified accuracy, but that is the test level for household equipment, industrial test level is 10 V/m, and automotive level is 30 V/m IIRC. I wonder if the result from 10 or 30 V/m immunity test would be completely different.

Regards,
Janne

[Kiriakos-GR]

Thank you Janne for the test ...  you had enter at the club of the braves , like it or not  

I would care very less , if the interference was effecting temporarily the accuracy of an measurement.

I do not care either if the UNI-T pictured above , by the interference of the mobile phone ,
it starts the beeper to make sounds ....  audible sounds , like the computer speakers do , when an mobile phone are active next to them !!

I had say this an in another topic , those latest high-tech multimeter 's , are computers dressed up like common multimeter 's .
This scenario makes them susceptible to common factors that troubles any modern computing system.
EMI or RF power or even common static electricity can kill them at easy ...

Yes I agree that at the automotive Fluke multimeter,
there is at list some awareness about this possible " issue " and the specs looks better, at list on paper.

The only comment that I can make , are that I am not aware any cars electricians that are willing to spend that money , but this is another subject, just by it self .

So the Metrahit Energy  passed the test ,  got in the river and came out dry ,
that's what matters the most , at list to me.


  

  

[MrPlacid]

If they fix it, just wrap it in aluminium foil to keep it safe from cell phones AND aliens.

Me no hero. But I did put aluminum foil in the rubber case. The one on the left doesn't have the aluminum foil inside.

[MrPlacid]

Hmm, maybe there is something to this "mobile phones cook your brain" theory 

I have always wondered about that since homemade bug transmitter don't have much juice to go very far.

[Kiriakos-GR]

MrPlacid  I like the way that you think , like running ahead for the cure .....

Its something that I expect to happen near soon ,  like  an  " upgrade pack for 87-5 extra shields " by Fluke.
I have not mail my multimeter to Fluke yet .. (Busy week )

My only comments - advices about this experiments of yours..
First the mobile phone must be active - calling some one or ringing , so to effect the meter ...

Secondly in order this " shield of foil " to act as shield , it must be connected at minimum with inner bottom shield ...  (metal cage )  Right now works most as antenna !! and its best to remove it.

There are aluminum strips with glue at the one side , used by the electronic industry exactly for this purpose, as bridge of external shields.

There is also another smart way about shields ,  by painting the inner plastic of the device with chrome based paint ... and copper contacts touching it from the PCB , an solution found on ACER laptops.
But I think that safety regulations will forbidden an such solution to be used on DMM that have to do with Industrial use and High Voltage !!     

[MrPlacid]

Kiriakos-GR, I am no hero so I didn't want to test it with the phone calling  However, what you said make sense such that I removed the aluminum and I doubt that I ever brick mine anyways.

I thought how fluke would rectified the situation such as painting the inside of the case.  But wouldn't in the long term, chip paint might cause an issue down the road?

[Kiriakos-GR]

Kiriakos-GR, I am no hero so I didn't want to test it with the phone calling  

In this case I prefer no posting with out reason ..  in this thread ..  
Why ? ... because Its possible to use this link , at the future,
if Fluke did not act wisely about supporting me.

Normally as human , after an such an damage at one so expensive hardware,
I should had loose all my hair by pooling them  , from my temper ..  

I choose to keep my voice down , and even the added video on the web , are with out tags and name,
because I count  on their cooperation .

I plan to respect them as company, at the same level that they will respect me , as an customer.

The specific " technical Issue " blows away any limitations about the warranty plan that Fluke apply by their own will , about world wide coverage .

If Fluke are unaware about this issue , my multimeter will get to Holland and from there back to USA for QC examination ...  and I will get an boxed one as resolution . (hopefully )

 
 

[EEVblog]

I've tried it!, and can confirm it's real problem. I was not able to brick mine though.
All filmed and edited, blog #112 on it's way...

Dave.

[jahonen]

I've tried it!, and can confirm it's real problem. I was not able to brick mine though.
All filmed and edited, blog #112 on it's way...

Dave.

Too bad you did not feed the DMMs with something real to measure, like a resistor in ohms range or some voltage (battery for example) in DC volts range. It would have been interesting to see if the measurement accuracy of the other meters which were not completely screwed up is affected.

However, getting consistent results in tests like this is often difficult, but Fluke made it quite so, by shutting itself consistently

Regards,
Janne

[saturation]

Let Fluke know, I'd love to hear the official word from them, and they do listen to eevblog.

I've tried it!, and can confirm it's real problem. I was not able to brick mine though.
All filmed and edited, blog #112 on it's way...

Dave.

[Kiriakos-GR]

I have pack my multimeter and its ready to be shipped on Monday 20 ..

Thank you Dave, that you did verify, by your test this issue.

I had took some high resolution pictures , of the DMM it self ,
some points of interest . 

Points of interest :
1)  some markings on the PCB  ( PCB details )
2) the totally unshielded area under the display , especially the left side.
3) Some dates of parts in it ... But I believe that Fluke does not needs any of that,
they read the Eprom ( chip data ) and they know all the details .
4) One screw half bolted on the low end of the shield , this screw does not move so to screw it all the way in or out ... an accident in the assembly line probably , and so I do not touch it further.   

I have wrote an letter to them , with not salty or either sweet voice tone.

Any way , I hope for the best, and I move on..

Pictures .. 


 
   

[Kiriakos-GR]

What vidz ?    Dave posted the video .... I am going to see that ..   

Thanks shafri for your good words , lets hope that the people behind the company,
are more friendly that the warranty documents that they print .

 

[Kiriakos-GR]

Nice video .... an true tonic for my current gray mood ..

I liked especially the advice ... Like let the Professionals to brick their DMM ..    
They can do it best !!  

Oh my .. 

I like to thanks Dave and the forum members, from the bottom of my hart ,
I had form the idea ,  that you can not found such of  support  in public forums  ..

Jee I need a Beer ...    

[Simon]

Kiriakos-GR! you are now famous i think, your name is mentioned in the vidz! i think more gals will be into your mail :

oh so thats how it's done  lets see what can I inocently wreck,.... hm no the rigol it too precious,..... the am220 DMM is not precious enough....... the VC99 nobody will care about, oh well looks like I'll never be famous 

sorry to hear about you fluke Kiriakos (and yes there is a pun there - fluke) it's amazing a company like fluke let that slip, from what dave shows in his video the multimeter is "tuned" to the GSM frequency (of which by the way there are two ranges 850-950 and 1850-1950 MHz - wonder which one is doing the damage)

[Kiriakos-GR]

I just checked some lists about the GSM frequency , Australia and Greece use both 900/1800 .

But I will put my bet on the 900 one ,
simply because you get more output from any transmitter, always at the lower frequency ..

The mobile phones has an single output circuit and antenna .
At the 1800 , they have lesser output , but cleaner band , so there comes the gain.

I was believe so far that at 3G ,  the GSM 900 works together with the 1800 , so to double the data bandwidth ,  on Daves video it looks that its not working that way ...
If it was , the GSM it should continue to cause trouble on the 87-5 .

Another explanation could be , that I do have right , but when the 3G gets active , there are both frequencies in use ,  but at an very lesser output.   

[Wartex]

Fluke 289, Amprobe 38XR, Extech EX530

[Simon]

I just checked some lists about the GSM frequency , Australia and Greece use both 900/1800 .

But I will put my bet on the 900 one ,
simply because you get more output from any transmitter, always at the lower frequency ..

The mobile phones has an single output circuit and antenna .
At the 1800 , they have lesser output , but cleaner band , so there comes the gain.

I was believe so far that at 3G ,  the GSM 900 works together with the 1800 , so to double the data bandwidth ,  on Daves video it looks that its not working that way ...
If it was , the GSM it should continue to cause trouble on the 87-5 .

Another explanation could be , that I do have right , but when the 3G gets active , there are both frequencies in use ,  but at an very lesser output.   

No 3g is a band of it's own I believe it is around 2700 MHz but don't quote me on that