Metrix MX56C / BK Precision 5390 Multimeter Teardown

[retiredcaps]

My other/working multimeter, the only one I have, is a trusty 20 year old Fluke 11, which I bought new back in the day.

Turn your Fluke 11 into a Fluke 12 as well thanks to a tip from Excavatoree. 

https://www.eevblog.com/forum/chat/fluke-25-my-first-digital-multimeter/

PS. Your 55C has some pads that might work?

[Vince]

I hope your weekend is free because I'm curious why your 53C doesn't support Hz and Surv like my BK 5360?

Oh, H/W hacking on multimeters !  I personally wouldn't want to hurt/damage the original looks of the meter, but I am curious none the less : is there a topic on here detailing these mods he did on you meter ?  What does this "surveillance" feature do ?

BTW I don't understand why you say my 53C doesn't support frequency measurement, as obviously it does ?  Your rebadged one too it sems, I see the little yellow "Hz" symbol on the front panel, just like on mine. Frequency measurement works just fine... so not sure why you added a second Frequency button ? What does it do that the built-in Freq measurement doesn't ?

PS. Modemhead did all the modifications, without schematics too  , on this meter. 

Hats off to him for reverse engineering the required portion of the meter.. but I hate going blind, it's limiting and time consuming, I am sure he would have used the schematics if he had them available at the time, unless this was some kind of reverse engineering challenge in its right of course ! 

Although I don't want to damage the case by doing hand modifications to it, I still like the idea of H/W so long as it's invisible from the outside, or S/W hacking and... actually I am thinking of a little something that I would like to try : I hate the screeching sound of the continuity tester... to me it really makes the meter feel like a crappy/cheap unit, which of course it is most definitely not !   So I am thinking of playing with my second 53C, the one I got for real cheap, to see if I can modify it to get a latched sound. Since the 53C has quite some board space available due to the unpopulated RMS and mA ranges stuff, I guess it could be possible to put some small SMD 74XX logic device and a few passives around it if required, to get a nice latched sound, whilst keeping the fast response of course.

Thanks for the link from Excavatore !  Interesting about the Fluke 10 series !  He says these meters are very prone to developing "black blobs" on their LCD... mine surely does ! I always felt guilty about it, thinking I might mistreated it somehow, but maybe I am not at fault then !    Still, doesn't keep it from working just fine, that's the most important. 

 Excavatore also makes me feel much better now, too : I was starting to feel guilty and silly for "collecting" a handful of old Metrix 5X... but I see he has around FIFTY units of a GIVEN Fluke model !  So even more if you add all the various models he has !  So, I now feel almost "normal" in comparison ! LOL

Learned about the existence of the 76/79 models too, which are improved /later revisions of the 75/77 which I was fancying, so I will start chasing the 79 instead of the 77 !  LOL   But prices seems way above what their specs command : found a couple on Ebay, for 100/120 Euros (say 120/150 USD or about), same price as MX55/56 or so, or my immaculate/brand new 53C.  So it would be unreasonable to buy one at this price :-/  For 50 or 75 buck though, I am in.

More generally I am happy to see that I am not alone in being "crazy"/very fond of old meters, and "collecting" them....  I don't feel as strange or lonely any more, thanks guys ! LOL

This latching mod sure will be one of my little winter projects/experiments ! 

[retiredcaps]

I personally wouldn't want to hurt/damage the original looks of the meter, but I am curious none the less : is there a topic on here detailing these mods he did on you meter ?  What does this "surveillance" feature do ?

Robomeds was the first to discover that the BK5360 extra pads actually work by pressing them.  No hardware additions/modifications needed at all.  That is, the functionality is already built in (just like the Fluke 10 and 11). You just have to find something to press the contacts.

The Hz and Surv are described in the manual as shown in the attachted picture.  More detailed info is in the manual if you want to read more.

Thanks for the link from Excavatore !

He also has an ebay guide for buying Fluke meters.

http://www.ebay.com/gds/Fluke-Meters-Main-Read-First-/10000000007231862/g.html

For the 70 series info see

http://www.ebay.com/gds/Fluke-Meters-Models-and-Series-main-/10000000007478323/g.html

[Vince]

Oh !  Sorry if I appeared a little retarded, I got it for the Fluke 10 series, but didn't for the Metrix !   

Thanks for the info then.  The surveillance mode doesn't seem quite useful for an electronic lab to me, however this "Herts" feature sounds really great indeed ! :-D  Still no way I am going to perform surgery on the case, however I am now well willing to spend some time hunting for an MX55/56 'C' to complement my vanilla 55, so I can play with this Hertz feature     Will probably take some time though, the 53C appeared very easy to find (or maybe I just happen to be searching at the right time and am lucky), however the more accurate/expensive 54/55/56, never mind the revised/later 'C' versions, are much rarer to be seen !  But I shall persevere of course !    The 54/55/56 'C' are also the only ones to feature a backlight apparently !  So that's an extra motivation.

Thanks for the links to the buying guides from excavatoree ! Never heard of this "buying guide" pages on ebay  ! Probably US only, as Ebay US is so much bigger than the individual smaller ebay site we have here in Europe, each country having it's own one, due to language and different laws etc...
This excavatoree gentlemen appears to have a really very severe "fluke" disease eh ?  A good thing though, hats off to him for collecting so many Flukes ! Impressive indeed.  I will make sure to take the time to read all the wisdom he dispenses there ! 

Now lets try and play with this Hertz feature on my 53C !   

[ModemHead]

The mods don't require any reverse engineering, just a little mechanical hacking.  The buttons are made from an old TV remote and some scrap plastic.

[Robomeds]

I believe the surveillance mode can function like the Fluke touch hold.  You hold the button until it beeps.  At that point it will record a stable reading and beep to let you know the reading has been recorded. 

[macboy]

The full version of the SX-DMM software package, which is compatible with these ASYC-II (ASYC2) meters, is now freely available for download at the manufacturer's website. The file you are looking for is "sx-dmmv2.9_0.exe" (or possibly a later updated version) and is found at the DMM support page at:
http://www.chauvin-arnoux.com/en/support/telechargement/results/dmm
You will also find some LabView and LabWindows drivers there.

I just noticed also that the meter is recently supported by SigRok (as of December 2016). The MX-56C is explicitly listed as supported, hopefull other models work too since the protocol is the same (though not all functions are supported by all models).
https://sigrok.org/wiki/Metrix_MX56C

Update: see post below for updated calibration software that works with newer versions of Windows.
I will also once again post a link to the calibration software for these meters. This is a direct link to the B+K Precision website. They sold re-badged versions of these meters with model numbers 5360, 5370, 5380, 5390. This software is compatible with all ASYC-II meters AFAIK.
http://www.bkprecision.com/downloads/software/AK5350.zip

A serial interface is needed for the any of the above software to talk to these meters. Of course they sold an expensive hardware kit to accomplish this, and of course it is long discontinued even if you did want to buy it. Luckily the interface is simple, just a UART at 2400/8/N/1. The physical interface is a IR LED and phototransistor inside the battery compartment. I used a USB-TTL serial interface (any one will do) and used a pull-up resistor and phototransistor on the Rx side, and a IR LED with resistor to Vcc on the Tx side (TTL level UART idles high, not low). You may need to reassign the COM port of your USB-UART to 1 through 4, then simply point the software to that COM port and it should work. You need to hold the "PK +/-" button while turning on the meter to enable the RS-232 interface.

The serial protocol is fully documented, in several languages, in a file called NF-SX-ASYC2.pdf.

I normally don't necro-post, but since this thread has become the definitive source of knowledge on this multimeter series, I decided it was the best place for it.

[Vince]

Thanks a lot for all this Macboy ! 

I haven't psote on here for a year or so, but have not been inactive on this front though :in the mean time, I bought literally a dozen of these meters !!!   

I just can't enough of them ! 

I did see an MX 56C in his carry case in like new condition AND in the case was... the serial cable/adapter and the raised front panel that goes with it... a gem... couldn't believe it ! Sadly it sold in an eye blink and I arrived to late.... 

[macboy]

Direct links to latest version of calibration software, compatible with x64 Windows (tested here with Win7 x64). The previous version linked in above posts is a 16-bit Windows application, so it won't work with anything newer than 32-bit Win XP.
 
http://www.filiale-de.chauvin-arnoux.com/sites/default/files/download/sx-asyc2cv23.zip
or
http://www.chauvin-arnoux.com/sites/default/files/download/sx-asyc2cv23.rar

[Vince]

Thanks for the update 

I ought to build a serial cable one day, and start fiddling with all my MX53/54/55/56 meters.. because hell, I just love these meters, it' s officially a disease of mine now, bought a dozen of them in a short time, couldn't help... 

[sergej]

Hello all.
I post photos of internals of my MX 56:

[shakalnokturn]

Are you repairing a broken via here?

[sergej]

Noooo :-)
I use this wire to safely recognize the vias on the other side of the PCB.