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 you.