New TE in the lab today !
My first bench DMM, the Metrix MX 554 we discussed the other day with Spec. Always fancied one of those but Spec was an enabler.
So here it is.
Very happy with it, it's best described as NIB. Zero dirt no scratch or dent anywhere. It's so perfect that it's almost annoying : the LCD window is like a mirror, reflects the lab lights like mad, makes it difficult to take a half decent pic, for starters.
Guy even sent me a printed copy of the manual, how nice. Even a brand new power cord and a brand new set of "Voltcraft" test leads ! 2mm ones with very sharp tips. Not "SMD work" sharp, but still very sharp. But they are crap none the less. Hard plastic hand pieces, stiff PVC cable, and non-gold plating that make the (unlatched on Metrix TE) continuity tester sound like you are trying to find an AM radio station, when rubbing the probe tips against one another. My sharp "SMD" probes are gold plated and even though they are cheap Chinesium, they make the continuity tester sound pretty much as if it WERE latched, when it is not in actuality. So.. gold plating does make a huge difference, it's not a gizmo. Cheap Chinese works just fine, gold is gold... even Chinese gold works...
So out with the Voltcraft leads... I salvaged the wires of course, always handy for wiring up power stuff.
Love the meter, glad I bought it. Quality look and feel. Love that large green/yellow LCD with mega huge digits, very easy to read.
From a technical perspective, it's 100% the same as a handheld MX 54, just in bench format but that's it.
So same exact features and pecs, same CPU ( 4 bit NEC, D75P3018) and RMS converter ( 1MHz Analog Device AD636), same everything, no more no less. So all good stuff then.
Quick test drive on all ranges but 10A, seems to work perfectly and agree perfectly with the handheld version.
I think the only reason I got it for much lower price than usual is that although it's in NIB condition... it's not NIB on all sides : the left side has huge dark red stripe on it ! Weird.
Seller clearly mentioned it and took pic of it so I knew what I was buying. Didn't care at all... you don't get to see the sides of a bench DMM anyway, only the front.. and the front looked like new, and is brand new now I can see it in the flesh. So I was more than willing to live with that red stripe on the side, if that meant I could get a pristine front and low price !
Stripe is like some thick varnish, nail varnish or something I don't know. I can just try to scrape it off of the plastic case with a sharp blade, then fine wet sand it to buff it out... will be just fine
So the specs and features are like the handheld version :
- 0.05% +/-2 digits basic accuracy.
- 50.000 counts
- high-impedance mode
- measures AC+DC combined
- Frequency
- capacitance
- Duty cycle
- peaks / min / max / rel / hold
- dB
- °C / °F temperature measurements
- "surveillance" mode, forgot what that does.
- baregraph with zoom feature
- opto-isolated RS-232 at the back to read measurements, configure/setup the meter, and also to calibrate it, cool.
Of course before I powered it up, I took it apart.
They didn't just slap the board of the handheld version into the cabinet no, thank god they redesigned everything from the ground up.
So we have two boards at the front. One that holds the main range switch + the power stuff ( input protection componentry & current shunts ). Other board holds the LCD and keypad and CPU
The main board carries :
1) The delicate analog stuff, all hidden under a shield soldered to the PCB, so I left that alone. The buzzer is there too.
2) The power supply. Mostly surface mount for all the small components. A lovely, big mechanical mains switch. Simple linear PSU : through-hole fuse soldered to the PCB, then a small molded transformer, then full wave bridge rectifier made of 4 discrete diodes but, it's a first for me : made of 4 big ass surface mount MELF diodes ?! First time I see a bridge made like that ! Looks neat though
. Then a single filter cap, then a 3 terminal adjustable linear regulator, good old LM317, again SMD, 8 pin SOIC.
3) The circuitry for the opto-isolated serial port. Opto isolation home made using 4 discrete LEDs / Photo trannies. The 4 white "cubes" on the board. Note how far apart they are ! Like an inch from each other !
I guess Metrix were taking their isolation a bit too seriously ! No need for a 10 Mega Volt isolation, calm down Metrix !
So that's about it for now ! I am super happy with the meter. Can't wait to have a computer set up dedicated to the work bench. Hopefully later this year. Would like to play with the serial port.
There is a thread on EEVblog about the handheld Metrix MX 53/54/56 series. ISTR a guy said he had a copy of the PC software to calibrate these meters, and he cobbled together an IR serial cable, easy enough apparently. Don't think this S/W can do the remote measurements and configuration though... manual says there is a special S/W for that, called " LabWindows DOS", for MS-DOS computers, and "LabWindows CVI" for MS Windows computers. I guess we are talking Win3.1 here, given the vintage of these meters. I don't know if that's a home made Metrix S/W or if they did it with Labview and just compiled it to get their own standalone executable files that they could distribute as being "theirs"... when in fact it's just made using Labview under the skin.
Will try to find a copy of these, though not holding my breath of course
However, luckily the manual does detail the protocol used to communicate via the serial port ! Gives all the Hex codes to talk to it etc. So that's really cool. So worst case scenario I could write my own little S/W to handle the meter !
.. or for basic stuff like configuring it, I could just use a terminal emulator and send ASCII commands by hand ! Yeah that would be easy enough to do, low hanging fruits and immediate satisfaction first !