EEVblog 1382 - Keysight EDU34450A 5.5 digit Bench Multimeter TEARDOWN

hi it's new test instrument tear down time we've got the new keysight edu 34450a five and a half digit multimeter this is part of their new educational series as you've seen in the new uh giveaway of videos that i've done and it's and probably the most interesting of the three new instruments they've got a new educational power supply and a educational model uh function gen 20 meg function gen as well and uh they're both the function gen and this multimeter are in your traditional oscilloscope like you know short uh compact when i was a boy oscilloscopes were never like this uh thick like you know they're out here like this but anyway the oscilloscope form factor uh basically they're uh reusing the tooling for their uh 1000 series um oscilloscopes at which you can get like an edu version of the oscilloscope and the whole idea is that they provide these four instruments for the educational market as all part of one big educational package so that you can equip a typical bench so i thought this is probably uh worthy of the first teardown just because it's interesting um form factor so let's check it out first of all you may have recognized the number the 34450a they're actually reusing a product number you can oh well you used to be i don't know if you still can but you can buy the 34450a five and a half digit multimeter and it doesn't look anything like this it's a big oled uh display one and it like why why reuse it why the confusion like that i like they didn't even call it b or anything but it's got the edu on the front so having the edu on the front exact same part number it's a totally different look and feel instrument ah i don't get it but it's 696 uh us dollars so yeah anyway um it looks like an oscilloscope and you can see that they've reused the tool in here because it's got a fan outlet here but there's no fan in it so yeah lan and uh usb as standard well you're either going to love it or you're going to hate uh the form factor so yeah whatever anyway you know what we say here on the eev blog don't turn it on take it apart except flatheads not going to do it hang on is it a five and a half digit or is it five to the power of a half digit hmm got that self tappers into plastic down here that's not pretty well they felt for all the world like self-tappers but they weren't metal threaded inserts they just had lots of loctite on the bottom of them so don't get your fields versus reels mixed up so it looks like we've got all the basic uh shielding you expect whether or not this is identical to their uh oscilloscope i can't exactly uh remember offhand but sucker should lift off yep we're in and there you have it whoa isn't that nice that looks pretty schmick got our processor over here and our multimeter measurement capability on a separate board very nice and a good old-fashioned transformer in there look at that old school you don't see that much these days ah brings a tear to the eye anyway i do like the cable management in there that looks pretty groovy i'm not sure what the deal is going on there with that connector with that like inline spay connector it's all terminated very nicely doing all the right things all your groundies down there i'm sure there are all lock tighted uh we've got ourselves a ferrite on the output here and big ass earth going over to uh the processor side of things because of course all your multimeter section is isolated that's why the only thing going over here is this and that guarantee that chip right there is an opto isolator so obviously not many uh connections it's a complete serial interface it'll be reasonably high speed uh optocoupler we've got our big shield over the measurement uh front end got some good old old-school relays i can show you a little uh quirk of that uh at the end when we uh power it up check out the front end this actually looks really good doesn't it i'm actually uh quite surprised to see the uh banana jacks soldered directly onto the pcb there got a couple of isolation slots cut into there two gas discharge tubes gdt's thank you very much uh two big ass mobs here look at the size of those monsters um what is that i forget what the rating on this thing is it's it's only cat two uh with the 300 volts which is common for bench multimeters you almost never see any bench multimeter above cat 2 it's just a thing for them but ah geez look at that that's pretty juicy tell you what look at those big ass deities over there that'd be across your uh fused your current shunt fuse and there's your fuse right there so that'd be uh back to back diode protection you know they often do that with a diode bridge but in this case yeah they're doing that with two big ass back-to-back diodes wow never seen one so large i used in a multimeter before so that's pretty nice um yeah and the fuse they've gone to the effort to wire this thing over so you know they could have maybe chose a pcb solution there but they haven't they haven't uh skipped i i don't see your traditional current shunt okay it's got to be these bad boys here you traditionally don't see that you usually see your bent uh like nichromey type wire current shunt um anyway we've got a range relay here and there's really not much doing over here these are just our voltage regulators just start powering some of the logic and stuff so nothing to see there attention to detail they have uh someone had fun with the silicone gun look at that they gunked it down nice and we'll be yes i'm still waiting on hold if you can hear that in the background anyway quick look at the uh processor board here and now you've got to think that this comes from another one of the instruments because obviously they have some sort of uh b and c over here so is this identical to like the function gen board hang on let me check the function no that's interesting both the function gen and the oscilloscope don't have anything in the way of a b and c there and of course uh look you can see up on the metal work there they actually have the b and c on the back like that um maybe on the function gen version of the oscilloscope i think uh might have that bit obviously reusing that processor board as you'd expect like they'd be you know crazy not to reuse the same board but anyway um the earth wires just they've just soldered it into there it's nikon bugger it we need to you know get a big ass earth wire over there and well that's one way to do it there's nothing inherently wrong with that anyway i won't bore you with the details there you go you can read that for yourself st arm micro one variant it is you got the memory and you got the flash and you got the whatnots and uh yeah not much else we're gonna there's that the ethernet yep and uh usb um and well not much else there you go is that the lcd flat panel driver i don't know it hasn't got many connections has it but yeah it's really not much happening there at all and well you wouldn't expect anything more and if you have any doubt that there are reusing the metal chassis there well there you go there's all your inputs for your uh four channel scope nice well you know why not all right so taking the cables off taking out a bunch of screws and gotten rid of the fuse holder and that should just lift out careful with the banana jacks they've got to lift out vertical and tada there you go there's the flip side oh we can take the metal shield off very nice check that out there you go for you jack aficionados there's none of that uh split jack rubbish this is interesting they've got a sneaky little bugger ferrite bead there here's it you can see the trace this is on one of the inner layers but going off like that and it looks like it's going under the ferrite bead yeah okay it's only cat 2 raider but yeah why you'd just rely on a layer for that sort of uh insulation beulah bueller beulah what the heck is going on here uh it looks like like some sort of touch switch but it's not because it's like it doesn't actually connect to anything as far as the case goes it's like around about here on the case it's just like it's not that so i can only think that it's um some sort of elaborate uh you know open air pcb spark gap but what does it connect to oh like mains earth or something uh it it could be it could be i'm gonna have to buzz that out um that would be my only guess because it's nothing to do with the inputs not like some spark gap because they've already got like real spark gaps here um it's nothing to do with that but here's the thing um neither side of this actually connects through to the shield here and you might think okay it'll connect down through to the chassis ground through one of the uh posts here one of the mounting studs right but look there's your isolation around your stud there there's your isolation around your stud there uh that one that one the only ones that are actually have something connected to them are these two down here sure enough there's a 100 ohm resistor to mains earth there so where's that where's that going yeah okay we've got 100 ohms in series with a mob here and in series with a spark app and then that bug is off yet then that goes then the other side of the mob so you got a spark gap and a mob in series by the looks of it and that goes so that's your positive input terminal that's your in ground input terminal but then the other side of that mob goes over to this spark gap in series with yep series with this mob which goes to your 100 ohm resistor which then goes to your mains earth so there actually are overload clamping that down to mains earth nice by the way all the input switching relays here they've all got isolation slots between the coils and the contacts nice touch and here's a nice little touch there your three slots for your shield i just unscrewed it there and you'll notice that this one will slide over and these will slide over like that then it just drops out nice design right so there's our big ass ac input coupling cap for ac measurements here they've got a catic resistor divider here so that's for the ranges so no you know that's what you expect you expect that in any five and a half digit uh plus class meter you can't well you can do it with discrete parts but it's just it's much nicer to do it with a ceramic array so no surprises there whatsoever uh here's our two uh input strings here these are for the uh sense lines here and of course they whack them in series for uh extra voltage standoff of course because each one will be a couple hundred volts and well 200 400 600 800 000 volt rating all right so it looks like this is our another input string here and that little inductor there let's jump over the via for that is there so that's coming from this relay here classic uln 2003 relay drivers here and they're buggering off to drive our relays so you can see we've got our coil side here and here's our measurement side so oops oh there you go you got one sneaky little bugger coming off there and going through can we see other sneaky little bugger tracers going off so yeah this is interesting on the uh contact side i'm not seeing any parts on those relays there and on the bottom side down here you can see some internal traces there but apart from that not much doing is there it's nothing exciting to see there all i can see is this little one buggering off over to here just one thing i notice here just from a routing point of view you can see these are going off here to drive the coils they drop they're on the top layer here tracers on the top layer they bugger off to an inner layer and just go over and drive the relay here oh whoa why i'm not seeing it from a voltage um like a clearance uh creepage reason so they're doing it again here i don't know oh no now i see you're probably screaming at me in comments it's very faint you can see this is like the ac couplet no ac coupling caps here but here's another input resistor here and it's actually going on an inner layer under these two resistors here and um over to one of the contacts on this side of the relay so yeah that's interesting why run them under something that's clearly on you know you want your once again they're relying on the thickness of your pcb layer there for your uh voltage clearance i'm not sure why you'd do that right so we've got our four relays here and our four inputs this relay here connects to the ac coupling cap this relay here connects to a 100 ohm uh resistor there in series this relay here actually connects through to the uh high end of the ceramic resistor divider there and this relay here connects through to uh this high voltage resistor uh array here so there you go there are four separate choices for our inputs um yeah i just i just don't know why they've gone under the why have they gone under the resistors i don't know okay dave tell us how you would have done it then well okay um clearly i would have uh well taken or these would have stayed on the top like this they go directly over to drive our coils over here and then i do what we what you're doing here uh the contact actually comes through the center here like this and then i would have put an isolation slot here and here so i could get because these are our contact size so this is a double pole double throw switch we've got one switch here which connects between there and there and there and this one here here and here and here and yeah i would have did or taken them out around like that and then put the isolation slots in there but they haven't they put isolation slots here and here and then run the trace under there and relied on the uh thickness of your layers between your pcb i i don't i don't get it anyway here's the interesting bit check this out they've got a keysight custom jobby here and we haven't seen this in other keysight bench meters it might be in the other because i haven't torn down the other five double uh three double four five zero a the one with the oled um maybe you know maybe it's an absolutely identical uh design to that one they've just changed the form factor and the user interface and stuff like that anyway you can see the little exposed guard traces there of course they do that for leakage reasons and you probably have to do a video on that dedicated to that one day but you know we're seeing that on uh low measurement uh stuff you know you see that in your you know femto amp amplifiers and all sorts of stuff anyway i don't know if it's genuine keysight custom silicon or whether or not it's a rebadged one of your traditional multimeter uh chipsets that would be interesting to find out if anyone uh out there and i'm sure there will be a lot of people interested um we'll i don't know check out the pin out of something like that so hmm high-res photos on the eev blog flickr account link down below so anyway that's going to contain our uh adc of course that's you know your traditional multimeter like a dual slope or multi-slope integration converter it's going to have the range switch and it's going to have all the other functionality for resistance mode and capacitance mode and you know all the other stuff so that's it yeah that's your traditional multimeter chipset and really there's not much else doing where the relay drivers as i said what's that one and that's just a dg412r mux nothing doing there what are these bad boys down here and a couple of lm393 uh comparators down there but uh do we have some yet some just some bridge rectifiers there nothing doing uh someone will say what's the brand of the electrolytic cap jh i can't say that rings a bell and before anyone screams oh there's no ptc's in here um did they got the mobs and the gdt's and everything well no they've got one down there it's um on this input string here of course they don't need it on all the input strings because well it depends on the functionality that they're trying to measure but anyway let's have a quick look at the input circuitry around here once again we've got a couple of uh 393 comparators there a bunch of uh ds for diodes they're not transistors uh yet yeah they're all diodes so a bunch of uh diode uh protection and whatnot and just a bunch of passives and of course all your multimeter aficionados are asking the one question sorry i had to get this far into the video before you saw it um the voltage reference of course no this is in the six and a half digit meter so you're not going to get your you know ltz 1000 sorry um you're going to get a renaissance jobby although that's got a fair child on there but you know it's all renaissance these days i don't know who's gobbled up who um anyway it's the 21r09 and this is voltage reference available in different uh voltage uh standards and it's no like 0.02 percent at best initial accuracy but of course the initial accuracy doesn't matter because you can calibrate that out what matters is the uh drift of the thing the p how many ppm telus ppm seven ppm so yeah debate in the comments down below whether or not that's good enough is it good enough for a five and a half digit meter is it overkill or is it just adequate and then we've got another arm processor there we've got a buzzer up here for your continuity we'll uh test that now because there's nothing left really um yeah i mean you could probably hack away there there you go there's some headers um don't have a connector on there they've been a bit naughty but anyway the jtag's there it's all labeled so knock yourself out so the conclusion on that is that yeah it's pretty schmick they've got you know all the dedicated parts with the relays in there there's you know no sort of like like range switch and other uh compromises you need to do in handheld multimeters so there are just separating out all the functions there and it all looks like you know relatively good of course you know only 300 volt uh cat to your rating you're not gonna of course because this is main mains powered you're not going to carry it out with you in the field or to a switchboard or you know to some big power plant or something like that that's not its job but looks like it has more than adequate uh protection and you can argue away about the voltage reference and uh and whatever i assume it's custom keysight uh multimeter chipset silicon down in there although i don't know somebody may have helped them out maybe they uh commissioned it from one of the multimeter chipset manufacturers perhaps i don't know is it the same is this almost identical to what's used in the uh existing oled model in the more traditional bench multimeter uh case the one that's you know the 34450a without the edu on is it basically an identical circuit i don't know never open one still works takes a bit of time it's gone through its cycle there and yep we're in now here's uh one of the quirks the absolute first thing i noticed when i plugged in this meter when i actually uh got it is that yeah here you go it's just sitting there we've got to have five and a half digits measuring one point uh eight millivolts yeah um it's supposed to do that so my 786 over here it's measuring something you know you move the probes around done a recent video on this this actually spurred that recent video on the number of powerline cycles so i take these probes so plug them in here yep there it goes it's doing exactly the same thing up there we go it's just cycling through it's just cycling through yeah it's switching and that's 10 meg ohms input impedance i switch it to auto which is high impedance mode it still it um and if we go to a one volt uh range here it just overloads because it's picking up the 50 oh no it didn't do it there you go oh overload uh because it's picking up the 50 hertz actually let's go into fast here because it's picking up there we go it's picking up the 50 hertz noise in the lab here and it doesn't have the number of power line cycles set to at least one um whether you're in uh fast slow or medium it still actually does this and if you set it to auto range actually if i untwist the wires i think that's why it's not performing like it did the other day listen to that relay look at that it'll really depend on how the leads are how much 50 hertz i've got at any one time that poor relay anyway i do have a video of of it uh actually doing it uh continuously and i sent it through to uh keysight anyway that's just uh yeah something to be aware of and from what i can find in the menu or can't find uh in the menu there is uh no ability whatsoever to uh like set up number of powerline cycles you got you know autod it has an annoying default auto dim with a screen dims uh she's why bother there's just nothing in there that i can find for number of powerline cycles anyway we do have a secondary measurement capability dc current so it looks like we can measure because we've got the different jack we can measure current and voltage at the same time beauty continuity here we go this is what everyone wants to see multimeter still has to have a fast auto ranging oh that's so slow yeah not for an everyday use meter but then again we are on slow mode let's put it on fast let's see how far she actually is here we go go up looks like goes up to a hundred meg there whoa it's just flapping around in the breeze there 100 meg hello that could be the noise that could be related to the 50 hertz pickup i'm sure because like you know this is going to be greater than 100 meg oh yeah there we go we're instant oh yeah look at that look at that bad boy no walkers and the continuity buzzer let's give that a bell well it's quick but it's so piss week i can barely hear that now i'm in a silent lab it's like uh 10 30 p.m here all silence and jeez compare that to my 786 same distance with the microphone pointed away huge difference ah looks like it's got zero ohms compensation so we could null that oh okay the uh pre-math oh look at that oh isn't that fancy pantsy zero compensation there you go look at that oh nice anyway unfortunately one of the things this thing doesn't have is uh your fantastic um trend plotting like live trend plotting that you get on the other hp no hp keysight bench meters unfortunately it just it it doesn't have it you can actually do our data acquisition though so you know if we go into dc vaults here we can actually uh acquire and we can go into continuous and then we can go into data log mode and we can trigger and we can have trigger count and sample interview data log on like that and the minimum sample uh interview you can do is one second by the looks of it i can't seem to go under that okay so if we data log on and then we can uh run run there we go so it's sampling once every second there but it's not going to give us a like a display so okay so we can just stop that then we can go into display and we can view our log and there you go that's uh the uh just the 50 hertz input crap that we were seeing there and like yeah there we go one to time like that um and that's basically all you can do and but of course you can export like you can uh because this thing's got full remote uh capability lan and usb and i believe you get this software with it although i'm not sure if it's full capability no i don't think it is no i think it's only like uh the demo capability of the software or something like it no it needs to have there it is that bloody relay again needs to have uh trend plotting in it just like the other keysight meters come on you've already got the software there to do it like how why can't you include it i don't know i i know it's probably extra work to include it but and you should get uh the full license to the software as well so anyway so look i'm not going to do anything more with this i want to keep this video under 30 minutes this is not a full review if you do want me to do a full review i can eventually uh do it and have a look oh we can have a look at capacitance here let's say go over you know i bet look um it's like a i'm not sure i how it compares with the three double four for the previous three double four five zero a but well it didn't have uh trend plotting i don't believe so yeah maybe that's what like everything's just nicked from that and that's and that's one of the problems like one of the main draw cards of the keysight bench meters is uh the trend plot in capability and being able to do that and not being able to set the number of powerline cycles on a bench meter with uh you know like five and a half dish sure it's not a six and a half digit made up five and a half digits and well keysight might do a firmware upgrade they have already done a firmware upgrade since i reported uh the auto ranging thing they fixed a few things but um it's it's still there because i've i don't know i've probably got a lot of 50 hertz here in the lab but um yeah no you can't have your relays just flicking around with uh you know it needs to have the ability to set the number of powerline cycles just set it to one or have the user option to do that and you'd never get that um it just wouldn't uh pick it up so yeah i don't know it's like a lot of people are gonna like the form factor they're gonna probably like the uh price point as well it's not that expensive but then again it's not that far off their six and a half like their low end six and a half digit uh models and other you know six and a half digit models on the market so you know but anyway um yeah there might be specials on it or something like that and it's a lot of people are going to buy it for the form factor and for the remote uh capability and all that sort of stuff you know you can script things and do everything and the hardware seems pretty decent but i like i can't help but think that they've just stumbled on a few hurdles um here and in just lacking some features that could make this a real killer multimeter i think um i don't know leave your thoughts down below am i right am i wrong being too harsh uh no that'll you know eat into the sales of their six and a half digit ones etcetera etcetera and oh it's only designed for the educational market and you know it's yeah okay but you know yeah it's probably like only like software things really so i don't know anyway that's the tear down of the new edu3450a five knife digit bench multimeter in an oscilloscope form factor if you liked it give it a big overexposed thumbs up because of the keysight black look at this bloody keysight black put my hand in there and it's just ah sure i'm a white pasty nerd but geez you know anyway catch you next time [Music] you

Channel: EEVblog

Views: 52,996

Keywords: eevblog, video, keysight, EDU34450A, 34450a, bench multimeter, digital multimeter, keysight technologies

Id: SR-3l6yrAXM

Length: 29min 48sec (1788 seconds)

Published: Mon Mar 22 2021

Reddit Comments

[u/JKZuchel]

Let's take it apart!