EEVblog #791 - Ebay Fluke 45 Multimeter Teardown

hi check out what I scored on eBay for just over a hundred bucks a classic fluke 45 jeweled a sleigh multimeter haha I used to lust after this thing saw it in the magazines back in the day yeah we're talking 1989 here okay this is before the internet the only place you saw this advertised was in the magazines of course the electronics magazines and have two full-page ad in there and ah I so wanted one of these babies why because it was I believe the world's first dual display multimeter you take that for granted these days but check it out let's pair it on and by the way this thing was bought like sold as-is so there was you know it wasn't shown working just you're not sold as-is that's it so I thought hey maybe it'll be a repair video and stuff like that well let's pair it up and see tada look Jill display your display I can see a bit of flicker you can see a bit of flicker on the display trust me that's not the meter that is the just the refresh rate of the camera so it's not actually too bad now this thing yes it had the beautiful second display on the thing sadly this one the vacuum fluorescent display on here is quite dim so yeah it's not the best oh that's not just the video here it's low it's pretty dim in real life as well and you could call up the second display here and look what else it had which was a Oh nope that's the board right it's that M there actually means a middle update rate but it actually had different update rates look at this fast update rate it actually have are twenty times per second fast update rate in three thousand count mode so in you know as a basic three thousand count you know it's three and a half digit multimeter 20 times per second updating that was brilliant for the day and then you could whack it in slow mode that's what the s there stands for and it had give you a hundred thousand count so it was better than four and a half digits back in the day four and five digits meant you know 20,000 count this thing and go up to a hundred thousand count and you can see that we actually got the extra digit there or in medium mode it'll do five times per second oh by the way yeah that's low 12.5 times per second updating so back in the day this thing was the Ducks guts the bee's knees Judas Lake and display say DC and the AC ripple superimposed on that at the same time I know that's you know that's nothing these days but back then that was a big deal and look it's also got a recent cow sticker on a June 2013 this is what made me dubious about the ad well her dubious in that I wanted a meter that I could actually do a repair video on and as you can see it seems to be like you know basically operational whether or not it's in cow I don't know I've got to get my cow meter out and check it but yet had a recent cow sticker on it yeah the plastic is yellow due to the bromide but yeah I think they just didn't really have the ability to test it and sometimes you can genuinely get that so yeah I mean not the not the world's best condition that yellow makes it look a bit yucky the vacuum fluorescent display is a bit dim but apart from that she's alright and it looks like it came from a company called power wave Technologies whoever they are and if you're looking to buy one of these yes you can use it anywhere in the world Universal AC mains supply input GPIB and this one had a very nice isolated RS to die believing it from Mary rs-232 out that could I believe give you like a standard string output format in so yeah terrific and made in the United States of America by John fluke manufacturing co incorporated beauty let's take a look at the data sheet for this puppy this was a really advanced for 1989 let me tell you as I said that Joule that fantastic Joule display which really set it apart true RMS of course standard with the well the G GPIB was optional but the rs-232 standard it could do our frequency measurements up to one megahertz kind of a big deal back in the day as with all multimeters they had you know DB measurements was that was a big thing for our and selectable low reference level as well so you know for audio measurements I mean that's pretty much gone the way of the dodo it doesn't matter if you meet a head you know audio DB measurement capability with references nowadays but back then yeah that was a big deal a big thing back then I had a high-low intolerance test for for automated production testing and that's II could program in your specified value and then you test your product on a test on the production line in a tell you whether or not it's within spec pass or fail fantastic 0.05% DC accuracy for current loop stuff it's got the famous fluke touch hold will test out the audio continuity and yes it had an optional rechargeable battery I don't know if this one has the battery inside I have no idea we'll do a teardown of this ahead close case calibration you can actually calibrate it through the rs-232 port that was a big deal for the time and there you go there's the different it count modes with the different updating very nice feature check it out this puppy can hold its own today we're talking about 0.025 percent plus two counts on all the ranges from 300 millivolts up to a thousand volts none of this you know different on the millivolt range or anything like that absolutely fantastic that's the one year normal accuracy the AC range it could go up to 100 kilohertz so you could definitely do the audio frequency range five percent at point two is pretty good for a true rms accuracy meter back in the day so that's awesome the continuity test a decent compliance voltage 3.2 volts so you can probably test you know you'd be able to test a white lib with that these days Oh point seven millions and naught point oh five percent plus two or three counts right up to 30 mega over the full range that's kicking ass on the ohms capability fantastic and is very impressive as well for a meter of the day 0.05 percent on sadly it didn't have a micro amp range so I only had a milliamp range but geez you know pretty impressive specs though for our current most meters don't do current all that well this one's quite reasonable and burden voltage a fairly typical and as I said jewel display we could just hit second there and we can go AC function like that and then put the AC in the second window there all we can actually do current I can't remember if it actually does current and voltage at the same time but oh no I think the eevblog curse is struck again it works ah what a bummer hoping to get a repair video out of this thing oh well hang on let's try 100 millivolts look that's practically bang on that's practically bang on 10 volts oh damn it there we go I've put it in 100,000 count mode it can't actually go to a hundred thousand can only go to 99999 so I've selected 99 9 there and there we it's bang on like I haven't even let this thing warm up properly or anything so you know that's it's pretty much bang on and if we go to current here damn it that works too is that within spec oh that's pretty good I think that's pretty good 1 milliamp oh look at that bang on one milliamp no worries whatsoever actually that current range is out of spec I calculate that is 0.26 percent it's supposed to be 0.05 percent plus 5 on the hundred milli amp range so odd to the 10 milli amp range it's actually auto arranged that too so yes slightly out of spec there but jeez I'm not going to quibble about that straight off eBay and using my really schmick really expensive weak on that inque lab reference standard yep it's within spec and it's basically given the same for my little homemade reference therefore 10k let's whack it in the 1k so we get almost at least significant digit yeah a little bit under but still within spec and check it out it can measure current and voltage at the same time ever voltage in the main display and current here or vice versa as we're doing at the moment and you can actually see I'm just measuring the burden voltage across the shunt resistor in this thing and you'll see that the four take it up to ten milliamps the burden voltage goes up by an order of magnitude there you go look at that a 1 volt burden voltage horrible horrible horrible evil but listen to this tick-tock tick-tock they're the relays inside it can't measure both at the same time it's got to actually switch the relay between the two different measurements but can certainly do it you wouldn't want to leave that running all day every day in some production but hey it's handy to be able to measure both can't calculate power though but here's a calculator or you gray thing in your head one of the really nice things about this meter is the serial output as I said but you can put it into what's called print mode I mean you can go into right here and set up your baud rate in your parity and everything else right that's all normal you go into second address here and you can go into print mode and what that does is that actually outputs this is how often it actually outputs data we'll set this to 1 and you select Auto there and bingo it'll out it's designed to output directly to a serial printer or in this case I've got a serial terminal hooked up so here's our here's our teraterm terminal and look it's just outputting text there we go as faster you know you can actually set the rate like once per second or once per hour or whatever and it will automatically output it in ASCII which is fantastic so if I plug in my resistor here here we go it's just Auto arranging there we go that's how quick it's updating 1k there's our 1k resistor that I've plugged in fantastic just text beautiful now this binary rubbish so if I set that print mode to 10 then as you can see it's happening like once per second or whatever now so that but that will depend on the rate so if I go the faster mode you can see it actually output sticks over that data faster and in slow mode it'll prob 1 2 3 4 5 here we go every 5 seconds we can set that to output data at whatever rate we like and we'll try the continuity buzzer that folks is as good as it gets beauty all right so let's open this puppy up and see what we have got inside and it'll be all through-hole tech 1989 vintage and by the way yes we have the full reference manual for this with schematics and theory of operation and everything I'll link that in down below ah calibration void is seal broken well we can let's get rid of that shall we you don't care about that here we go and slide it should just slide off yep no I let some surface mount display technology or our fancy pantsy fancy pantsy look at that no battery option we're in like Flynn because I am presuming that the battery option goes in here look at that ah there we go conductors she'll may have voltages present have ourselves a nice big HRC fuse down there thank you very much that's for the 10 amp range of course but it doesn't because there's a yellow wire that's the 10 amp range going down there it doesn't is there no fuse oh yes there is sorry yet there it is there's also a fuse in the holder that you can now get off the front of course you screw it off the front panel so that's a your fuse for the milliamp range there you go just a little standard em 205 they're not a HRC type someone could've replaced that I'm not sure if the original had HRC or not and there's our 10 amp current shunt right down there for terminal 1 of course it's just the nichrome like rod down there very very common so no problems there at all and you'll notice the isolation slot cut out here's our voltage input okay this is our main one for voltage and resistance everything else nice big cutout slot in there for looks like they got two separate resistors are tapped off there to input protection resistors so that's very well done it looks like mostly wrong about this being through-hole it's we've got ourselves a PLC C processor it's mostly through-hole and you can see that our separate GPIB board up here this was the optional extra that you could plug into the thing says copyright 1987 so that's interesting yep there it is copyright 1987 mr. John fluke himself yes so that was a bit earlier I thought it was 89 I stand corrected all right I've taken the GPIB board off so that we can actually have a look down in the guts here and well the first thing I notice is the rs-232 here you can see a well the cables coming down sorry you can't see at the back but this is the rs-232 connector here this is all the digital side of the stuff here's the main Hitachi processor look at that the EEPROM everything else then we've got the optocouplers here nice big huge isolation between and these massive optocouplers in here that is the isolation between all the measurement capabilities so we're going to have our fluke ASIC under here and our ADC and everything else all under here and that simply comes across the opto coupler and we've got a transformer here that'd be getting that power over to the other side so power isolation not transforming we'll notice that we've got some caps on the other filter caps on the other side there so that'll be rectifying that and providing isolated power over here that's why they can get away with the rs-232 being connected directly to the rs-232 driver there it's all common ground for all this digital stuff and that's completely safe because none of that goes external it's all internal so yeah completely isolated transformer up there couplers no worries whatsoever you'll notice that we've got a huge mains filter input cap here we'll have a look at another angle in a sec so this is the mains transformer coming in there we've got ourselves a just a couple of diodes in there for rectification filter cap here's the battery connector right up here it's not populated but that's where it plugs in so I think that's part of that we'll have a look at the schematic for that in a minute and of course spared no expense Nippon chemi-con caps no worries whatsoever you'll notice that the switch is right back here on the PCB why is it so you should know that I'm a big fan of those push rods and having the switches all the way back rather than run cables right to the front that's really messy they've put the switcher right where it needs to be on these high current traces for switching in the well they've got to switch in between the battery and the mains transformer so that's not a main switch if you have a look over here here's our buy AC mains input connect to here it's going straight in straight into the transformer both wires there there we go bore me in like Flynn and they've done the earth connection properly you'll see that going down there yes they've got a shake proof wash it down on there but what's interesting it's another earth connection here and on the other side I'll give you a better view of this check it out see they've got another well it's an earth why because it's connected to the frame of the transformer which is connected through to the chassis of course which is connected to mains earth so it's mains earth it's going into the transformer and as I said there's another green wire right down there if you can see it that folks must be an internal electro snake shield between the primary and secondary very very nice they use that in top quality isolation transformers actually like that one over there that I've got that isolation transformer it'll have a earth shield between primary and secretary get to get the capacitance down between them to get any capacitive coupling between primary and secondary it's just a really safe way to do it so there's no capacitive coupling no energy can get between primary and secondary very very nice actually just as a little aside if you've never seen inside one of these isolation transformers by the way every good lab should have one of these safety isolation transformers just allows you to work on equipment safely because it isolates it from the mains supply the primary and secondary so yeah got tore tech Australian manufacturer of these things they're been making them for decades they're one of the leaders in the business and this one it's a huge toroidal transformer one awesome but you'll notice it's also got the electrostatic shield in it here we go we've got that the input mains earth goes down to here of course and then you can actually see it coming off here and you might be on there we go you can see it anyway it's going into the base that it's going inside the transformer because they've got an electrostatic shield it's called inside between the primary and the secondary so that cuts basically cuts the capacitance completely down to zero so there's no coupling between the primary secondary so common mode noise actually stays on you know it can't get through from the primary side over to the secondary so that's going to be that internal electrostatic shield is going to be closely coupled to the primary side so felucca doing exactly the same thing inside this transformer to get that common mode noise down very nice check it out folks state-of-the-art processing power the atashi HD 6303 this is a 6800 series compatible it's sort of like a later variant of the 6800 backward-compatible it's got a built in serial communications interface fantastic so hence it can drive the rs-232 directly up here within the chip fantastic modern technology I just love it and of course none of this a squared prom rubbish inside so we got ourselves a separate national semi 63 C 46 down there to hold presumably the cow values we've got a shielding plate on the bottom so we'll whip that off and as you saw we had a conductive shielded box on the top side it's mostly shield on here but what you really notice the guard rings check them out explain God rings before there we go criss-crossing in they're designed to stop leakage between individual nodes in here so they obviously don't care about leakage between these two nodes ie if you're getting any contaminant or our condensation on the board between those two terminals doesn't matter but it certainly matters if it's between that one and that one there so they put a guard ring around that and that's kept to a common circuit level and they're all connected back to that common via down there so that would be a ground reference guard point in as part of the analog to digital converter circuit and by the way we have a date code on this puppy there we go first week 93 for that chip there so yeah we're talking probably early to mid nineteen struction well untruly lifted the skirt on all the ADC front ends section so let's take a look at it as I said here's the main voltage input here and here's our two input protection resistors here what are these funny-looking things there's a cutout slot underneath that if you can see it there we go you can just see the slot those are going to be surface mount moves let's go to the schematics so here's our four front panel terminals here here's our common here's our 10 a.m. p.m. port of course there's our big HRC fuse going straight into the current shunt Bob's your uncle that's all fairly typical for terminal tapped off that of course you've got to tap the ground off this side of it not from that side so your tap from the signal side anyway that gives us our 10 mm put here here is our milliamp fused input so that's that's showing that the fuse is in the holder on the front looks like we do do we have another internal fuse I must have missed that anyway that is going through our current shunt resistor for our milliamp range I can show you that in a second and bingo here's up mom's here which I go down to signal ground and here's our positive inputs here so a positive input goes across here here's one of our resistors r5 and r6 here these are our two resistors that we saw across that isolation slot and bingo we've got effectively then two moles in series going down to ground at that point other move here is connected on this side of the other big input resistor across the slot there through a PTC here so providing some overcurrent protection they're actually the real board is slightly different to the schematic you can see our five here comes across it goes into one of our moles here okay which is the other common side to this over here but then it also goes into the the high voltage input divider here one of our thin film our ceramic hybrids one of three on this thing and there's our PTC there so what's going yeah it's actually different than the schematic hmm yeah substantially different this shows three moles here and we've only got two down in here so yeah it's a slightly different configuration might have a version difference here anyway past our input protection there however it happens they go through the relay contacts for the various range is nicely annotated there so you can figure out those for those playing along at home you'll notice that all these resistors here it labeled z1 that is because they are part of the input precision thin film resistor network in there very common high stability though reason they build them on the ceramic bases they're incredibly stable they still do that today of course and this puppy has no less than three of them very nice basically what that translates to is you're going to get very little drift over the years they're going to be super high quality super low drift a super precision and they're going to be matched as well so it's very likely that if this thing is in calibration on your 1 volt range it's going to be in calibration you're ten volt range for example if you're wondering where that guard ring on the PCB was connected to there we go it's labeled God fantastic I know you're saying show us the reference son well all right here it is vr1 there we go it's just a Zener diode well when I say just a Zener diode it's selected with a wise old man with a gray beard as he strokes it okay maybe not that good in this class of instrument but hey the production test jig that actually measured and characterized these things in selector that would have been set up by a guy off the gray beard and here's the main output from our analog processor chip this is a custom a fluke ASIC of course they rolled their own Asics they still do I think so yeah and once again there's those big optocouplers we saw going over so it's just the serial coms data come in directly out of the ad converter itself for those playing along at home there's inside the big custom fluke analog processor it's got multiplexers and switches and all sorts of things it's got the voltage of reference for the ohm source and everything you could possibly need to roll your own front end converter you can see our input signal here being AC coupled off here goes through some real eyes up to a a c buffer up here and then here is our true rms converter it's off on a second board which I'll show you and they've got a separate schematic for that so there you go there's the RMS output there so they can actually feed that in so yeah that's pretty convoluted geez warning Will Robinson warning and we have tech dipped tank 10 alums look at them evil evil but there we go classic what else do you find in a true RMS I convert it in a multimeter mmm analog devices 86 37 gone so why would they actually have that on a separate board why not it's not like a paid auction why not just whack it down on the main board well I could have squeezed it in it's probably not a space issue there but my guess would be that maybe they secretly do offer a non true RMS version just an average responding version that's quite common for the military market actually because they got all their test procedures and everything for you know use a multimeter on a boat or whatever they've got all these test procedures written for how to test stuff using an average responding multimeter and you can't have any of this new thing called true or RMS rubbish no they'd have to go rewrite all their manuals all the tests manual so they will order specific non true RMS average responding our versions of various our fluke meters that's actually quite common in those point one to MFD caps look pretty special MFD of course is micro farad now this nano farad's rubbish no siree Bob back in the day capacitors came in micro farad's and pico farads puff and that was it so if you wanted a one nano farad cap was point double o1 micro farad's thank you very much anyway the reason that looks so special is because that's probably some sort of high stability even though it's plus minus ten percent the absolute tolerance doesn't matter it's a very temperature stable cap this is part of the active filter circuitry and it needs to be stable so they've probably got a polystyrene Polly put the kettle on and capacitor in there and of course it would be end of life as we know it for the volt nuts if I didn't show the reference diode there it is just sitting there not getting into it not getting out of it it was best straight or something they're not getting you know what not getting out of it but said what is best right or something the thermostat as a matter of fact ladies that cop I said your chugger might a cop I'm getting outta here let's go she said no why I'm hanging around all gun ways well there's the main fluke analog processor well it's about or she wrote so here's a power supply schematic for your power supply aficionados and let's have a quick squeeze at it here's our mains input transformer as we saw there we go there's the internal electrostatic shield you can guess see it going down to the earth there and as I said this thing is always on here is the actual on/off switch after the full wave rectifier here so as you can see in the off mode it can actually come in from the battery here the battery board connects up to there and we don't have that battery board looking at the circuit for that but as you can see the lm35 78 here with our transformer here and our output diet here there we go that's forming the +5 volt the main logic supply voltage and you'll see that actually it's a really weird arrangement how they've drawn it's just like you know it's not very typical so it's not obvious at first glance but here's our output diode and here via our output resistors here here we go there are current they can't sense resistors I think they might be tapping it off therefore current limiting it goes out here bingo there's our +5 volt rail and that 5 volt output after the current sense resistors it's they're not powering this oscillator here for the primary side of this switching converter here and this is a another convoluted arrangement that gives us plus 5 volts and Plus 5.21 not sure why they need 5.2 anyway our 5 volts am AC minus 30 volts minus 5 volts and yeah few rails to make this puppy work and then we have our vacuum fluorescent display board and all the switches as well they're a vacuum fluorescent display driver that's the UPD 75 1/2 or 75 to 1/2 I try and link in a datasheet actually that is different again it's UPD 75 to seven a this is actually a 4-bit micro believe it or not actually that front panel display board look copyright 1996 does anyone know the exact date they release the Fluke 45 leave it in the comments and by the way the manual says this thing used an 8 volt rechargeable battery pack it's rather bizarre here's a photo of it and what's the standby power consumption with the switch off well just over 1 what that's all right with just the transformer and the output rectifier and filter caps energized and we're looking at 8 V a the power factor is awful as you'd expect so I hope you enjoyed that look at this venerable fluke 45 the world's first Joule display multimeter from the late 1980s an absolutely classic meter that still holds its own today spec wise so if you can pick one up in good condition at a reasonable price do yourself a favor and get one because they're a really nice little bench meter I like them so even though the fluke 45 seems to be one of the forgotten meters of the era or one of the forgotten fluke meters it still seems to hold quite a bit of premium on eBay so you know you might have to be patient to pick one of these puppies up but you know if you can by all means do it and as always with my tear downs I'll have that some high-res photos I take as I disassemble the thing they'll be on my eevblog comm website so check the link down below and as always you know thumbs up and yeah not a fake thumbs up please from paid bots real thumbs up only in that direction thanks catch you next time [Music] you

Channel: EEVblog

Views: 80,204

Keywords: Fluke Corporation (Business Operation), fluke 45, multimeter, dusla display, world's first, teardown, pcb, voltage reference, zener diode, logging, serial port, voltage, current, measurement, resistance, standard, calibration, procedure, check

Id: mK-Sc57SA0I

Length: 33min 4sec (1984 seconds)

Published: Mon Sep 07 2015