Hi welcome to Tear down Tuesday Yes, it's Retro Multimeter time. Check this puppy out. It's a it's a digim 10 from a company called Iscra and uh, it's actually a Yugoslavian made multimeter. I mean you know, real retro.

It's not a modern design. Check out those uh for Mm banana socket um inputs there really ancient but OB viously some sort of lead display in there and uh, we've got the manual for it. It was sent by Silvane, um he's an EV blog? uh viewer? hi sane, thank you very much. Sent it into the mailbag segment and we saw that on there and it's even got some Uh tips for using this sucker on the back.

There it is and it's in really quite good. Nick And we have the full schematic which I'll link in um down below which is in the back of this. Look at this. got the original manual for it and the fold out schematic.

Fantastic. So I'll scan that in and that will be linked down below. Actually the circuits uh, rather fascinating and uh, worth a look. I mean check out the Uh power supply down here.

Look at this. We have a discrete switchin power supply. It's even got the Uh switchin waveforms down in here. for example.

what do we got TP 2.1 There it is. Uh, plus five. We' got a multi vibrator, classic two trans system multi vibrator circuit here and uh, that allows it to generate the required Um supply voltages for this thing. Really quite neat.

Our display driver up here. look at what we've got. We got an MC 45511 uh s segment, um driver absolute classic and it really LD Triple1 looks like one of the looks like the main device down here. There's an LD uh 11 and it Ld11 so it looks like it's a two chip Set uh multimeter.

haven't seen these ones before I'm going to have to Google that um see if we can get anything on there and uh, once again, we got more waveforms down here I like it got some uh opamp action down here. Lots of, uh, quite a few trim pots in this thing I think I can see we got one there one there. we've got a discret uh jfet input there by the looks of it and uh, here's our input. Yeah, here it is.

over here. Volts and ohms going in. We've got some uh yeah, compensated uh. 10 mega resistor there.

we've got a SS another trim pot down there, another trim pot, trim pots absolutely all over the place and this is rather unusual down here. Look, these are these are resistors, but they've actually, uh, look how they've actually drawn them here. um, like their inductors or something like that. I don't know.

Really weird is that common in Yugoslavia I Don't know any viewers out out there? Please let us know. but uh, that's our current input there. There are different, uh, range switching. I'm going to assume that that means these are wire wound resistors so it wouldn't uh, surprise me at all if we open these up and found uh wire.

You know, wire wound resistors in there, but why You' use like a 9k wire wound resistor up here I uh I Just don't know, but you know it'll make sense for you know, the lower um current shunt ranges. Of course it's got really nice. it goes down to 20 microamps full scale. Check that out.

Really quite neat. So it's rather, uh, quite a usable meter. I mean anything that goes from, you know, 20 micr full scale up to Uh 2 amps is going to be, you know, is a pretty useful multimeter milliamps. it's got AC and DC I assuming of course it's not true RMS It's just going to be average, uh, average responding there.

and uh yeah, that is quite neat. Goes up to 20 M 200 ohm um minimum scale, but quite a usable meter for its day. And you guessed it, it's got a triple five timer. Beauty And check out this.

Legend Down here here are the different types of resistor symbols that they're using in this. If you've been wondering why they look a bit weird ass and you know, look, these are carbon film metal film power resistor. haven't seen that before using different home symbols like that Once again, is this a Yugoslavian thing? I Have no idea? See? Yes. Obviously.

Uh, you know it needs plus - 12v uh rails here to power the main chip set over here. so those ones operate There we go. Uh, plus and - 12? Where's Plus? There it is up there. and if we have a look at some of the specs here, there we go.

It's R for operation at 23 C uh operating temperature 0 to 55 storage temp uh frequency range for the AC of course. uh 30 HZ to 20 khz. Um, once again assuming average responding powered from four uh, Nikad batteries. There you go.

Um, recharge time 16 hours? Uh, doesn't tell you what the Uh consumption of this sucker is, it might up here anyway. Standard 10 Meg input impedance Um, they even specify the capacitance there. three readings per second. Not bad at all.

Um settling Time 1 second Max for all DC ranges so looks like it might have a bit of a settling issue there. And and maximum potential on the Ohms V connector with open sockets plus - 14 Vols Huh? And there's our measurement ranges. Goes up to an impressive 2,000 volts DC I You know that's very rare to find that uh, the only ones I've seen above a th000 volts or an old Um triplet analog meter I've got here which I go think goes up to 6,000 volts or something like that. but uh yeah, very handy I mean 20 microamps full scale the maximum reading.

It can actually go um over range just a little bit. but have a look down here, it's actually quite impressive. Um 0 2% of reading and .1% full scale with and it specifies the temp Co in terms of Um per 10 Kelvin look at that instead of uh per degrees C but that's pretty good. You know, even on DC current, you know 0.2 Not bad at all.

I like it 2% for Ohms, this was pretty good for its day. and there's our block diagram uh, nothing really special of course. got the input attenuator and the Ohms to voltage uh converter for the Ohms range your current shunts and then it's got a the triple 5 timer um in there was obviously Um operating the Um analog to digital Uh converter there with the voltage reference I didn't have a look with voltage reference and then we've just got a basic BCD to 7 segment decoda to drive the Um lead display and the converter in there and a Um AC Todc um average responding converter. So let's crack this uh puppy open and uh, we have some sort of little key lock here on the side.

I'm not sure what that does that does that? Just no, what is that? Wh oh there we go. Oh, that's our fuse. There we go. Oh Beauty I Like that, there's our fuse.

We'll put that back in. there. we go. It looks like, uh, probably these four feet on the back here, do they? Yep, they pop out.

Oh oh, hang on, what's that? We' got ourselves I don't know what that is there. Oh, it's one of those. um yeah. I don't know the name for those actually.

but I might have one of those in my kit. Yeah, there we go. I've got uh, one of those those little two-pronged ones the Name Escapes me at the moment, everyone's probably screaming at their camera going. oh I know what that is and uh yeah.

Well okay now I need a bigger one? Aha I found a date code. look at that 7th month I assume it's a date code 7th month 1980. Yeah, that would be about the Vintage that uh, this that? that's probably what I guessed uh, would have guessed you know, late 7s, very early 80s. um at the outside.

So woo, 33 years old folks. that's probably older than the age of my average audience. So yes, this will be, uh, rather interesting. I mean it's going to be all uh through hole of course.

uh, surface mount wouldn't have, uh, made its way into something like this back then. So I expect uh, you know. um I well I don't know the quality of the construction I have no idea about uh, this brand. never even heard of it before and uh, but we'll have a look for a 33y old technology Anyway, all through hole, you know, probably no solder mask on the board or some or anything like that'll be uh I think that's done enough and uh, it'll just be like a t.

maybe a tined um board? PCB or something like that. Uh, we'll see how the I'm not sure how. the um, probably two board construction. Maybe for the LCD something like that, perhaps? Anyway, um, it should be fascinating and don't expect uh, you know, cat input rating on this thing and uh, huge input protection and isolation slots and all that sort of stuff.

No, they didn't care about that sort of stuff back then. Heck, even the flukes really? uh, weren't wh better not lose those. Hang on better. Chase It right here we go.

Got them out and I wonder if the batteries are still, uh, still in here? No, they're not there. we go. Tada There we go. There's our four Nik heads I assume it would, uh, work off um, alkalines as well.

Check it out though. this is H Chock full of retro goodness. We got ourselves a little shield on the top. there twang.

kind of a a couple of adjustment. What looks like adjustment. uh, caps there. probably for the AC uh performance there.

and uh, what have we got down here? Looks like that's weird. Looks like maybe some sort of something. one of the wire W resistors. yeah, there's a monster inductor or wire W resistor there.

Not sure what's going on there, but uh yeah. basically. um, two board construction. It looks like the KN three with the LC with the LCD LCD sacrilege.

Wash my mouth out. um LED down in there we'll take a look at this. Actually could be real. Uh, tricky to take apart.

I've got to get all these off and then these have to lift out and then the top board. Who knows what the rain switch does anyway? Um, check out here. There's our battery compartment for our 4 I KR 23342, 43 um. Nikad batteries and uh, there we go.

If we have a look at the board down there, it looks like it is, uh, looks like it is gold plated down there. hand, um, drawn. PCB that looks like it's done with a good old Del pen or something like that. By the way, it got the original plug pack for it as well.

Um, Silvane sent that in. and there it is. It's even an Iscra branded uh plug pack. Check it out! Fantastic! Oh man, that does smell as old as it looks, folks.

Oh, that old electronic smell. So we'll whip this Shield off here and uh, hopefully we can just, uh, peel it off layer by layer cuz I haven't ped this thing up yet I don't even know if it works. um Svane didn't mention whether it works or not. Whoops There we go and oh wa look at the range switch.

Oh this is a beauty folks. Check this out! Have you ever seen such a sort of, uh, you know, um, sort of slap together Heath Robinson is uh, type um Contraption range switch. oh my goodness, that is. That is just really something.

Look at those contacts in there and sort of, you know we got these wires just bodged across the board going down there. We got these wires going down here. big beefy things I must be carrying the uh range. um, sorry, the uh current.

Anyway, let's see. here we go. It's about to pop up so we'll be able to see this contact here now. Pop into place.

Ready There we go. So that one just oh man, that is really that is really something. Look at that. Wow that that is bodgy.

Brothers But actually, the more I look at that, the more I think well, that's a you know that is actually rather clever I mean you know it looks all bodged together up the top here, of course. but the actual uh Arrangement itself there, um, isn't that bad? I'll see if I can. let's see if we can, uh, switch this here. Look at that at that.

That's actually just really quite quite nice. The more I look at that, the more I think yeah, that's really rather clever. Look at that somebody. Somebody had fun anyway.

uh, designing that and we have all uh, goldplated uh tracking there of course. Very reminiscent of uh, say the early um HP uh, gear and stuff like that. um, that's you. know, you don't see that anymore.

you, can't. Just you know, piss away the gold these days with gold prices the way they are. of course all of that is, uh, hand taped of course. back on the old, uh, you know, days of the light boxes and stuff like that when you put in the curly traces and everything else.

Beautiful. You don't see that anymore these days now because the nature of how these boards are wired together like this. They got the wires going down between the two boards like that, the wires and then uh, cables. um, snaking over the top like that and they got the same love this ribbon.

pink ribbon. First tear down that contains a pink ribbon. Make of that what you will? um, and of course they've wired these boards together like that. So so it's it's really not designed to come apart and I'm really, uh, quite hesitant to take those boards off.

but I'll take um, these, take these nuts off and see if the entire sort of assembly, uh, lifts out. but yeah, I don't really don't want to go? uh, cuz I haven't powered this thing up I Really want to see um what it's like? but yeah, I don't oh man, it's like I really don't want to. uh, don't want to ruin the sucker there. The other no, what's that I thought that was a switch, no that that's like some big ass inductor down in there monster.

But uh yeah, this is probably the one of the most difficult multimeter tear Downs I've ever done because it's just wow. So handbuilt and just man not designed to be Mass assembled designed for manufacturer. What's that? Just build it and ship and in there you can see a traditional uh PCB Mount uh range switch with the uh, like a wafer uh type switch there uh contact switch going between the etched uh, goldplated things on there and it looks in really good Nick actually so uh I'd be surprised if this thing uh uh doesn't uh work anymore and it's you know, probably still within spec. so before I actually uh, attempt to take this apart I will actually power it up so got external 5V uh Supply there hooked onto the battery.

so uh, hopefully let's give it a go, shall we? Let's put it is that the voltage of the battery I guess let's turn on. Hey there we go. Yep, there you go. It works.

5.07 um well my power supply is showing 500 but I could uh, measure that with a multimeter and see which one's more precise? No, there you go. it's a little bit out reading the battery. Ah well, you can't have everything but uh, there you go. It seems to be working.

A treat at the very least. Awesome. And what do you know? I've got that hooked up to my Uh Calibration Lab calibration standard here set to bang on 2 volts. In fact, 2.0000 volts and we're getting 1.

N97 that's within spec. And by the way, if you want to know the current drawer, uh, just over 200 milliamps there. So there you go. That is fantastic.

Ah, it's a thing of beauty Joy Forever, let's overload it. Oh Flash In flashing warning Will Robinson Warning Let's measure my uh resistance standard here. It's like a 05% good enough to measure this puppy and it's really good. These are Jewel adjustments I You haven't used a multim media like this in a long time and you you know you move it around here.

It's annoying. it doesn't work at all. You've got to actually switch it over to OHS and we're bang on. We are bang on folks.

Not a problem whatsoever. Awesome! This thing 33 years old can't beat Yugoslavian technology. There you go. 1K Let's switch it down.

Oh there we go. That's pretty good. That's pretty good. Oh, give that a win and if you put the leads open, there we go.

It just goes full scale and just uh, flashes at you. And of course, no continuity buzzer. And there's something seems to be something wrong with the current range here. I've got it on.

uh, 200 microamps there and it's uh, flashing its digits at me and uh, shouldn't be doing that because I'm only feeding in 10 Micro amps there. So really? I don't know, don't know what the deal is there at all. and uh, well. 2 milliamps? Yeah, there it is.

10 microamp. So the 2 milliamp range works. so let's wind the wick up on my Keithly current. Source No, no, no, no, that's not budging.

No there something that's supposed to be like 100 milliamp? No, there's something wrong with that, but that's prettyy cool that that puppy still works. So Let's uh, see what happens if we try and take these Boards out. Actually, there's another shot of the contacts down in there and they've got numbers on them, which is rather quite neat. and you can see those, uh, it doesn't seem to be uh much if any wear on these contacts at all.

Very, very nice. But you know it's almost as if like these have been bodged on as like a, you know, an afterthought or something like that. cuz that you know, cuz that range switch instruction is, actually, uh, rather quite nice. We might get lucky.

The range switch looks like it's just going to pull straight off the screen. the um. lead display is coming out. so I better.

Oh no, hang on. uh yeah, sorry not keeping that on camera too busy wor there we go look at that. There's our range switch down in there. there it is I better like leave it in the correct position, but nice balls in there I Love a multimeter with a good set of balls.

Interestingly that uh, red perspect window is not held in with anything, it just just sits there Well, if it did have some glue on it, it's uh, worn off with age. And there we go. We have our lead display and the top of the board. Look at that interel chips.

Check them out. There we go look at at that well there right the LD 111 And there's our Triple 5 timer. Beautiful. Yeah.

Confirmed our manufacturing date: 20th week, 1980 25th Week 1980 Fantastic! 4511 Le Display Driver: Oh look at that. We've got ourselves a uh, looks like what was supposed to go to a shield and you can see the mark. Ah, it is has that got that shield in? Look at that. They've actually exposed that and that is like a like a nickel Shield or something like that.

Yeah, there we go. That's for real folks. Excellent shielded front cover. Brilliant! Now as for the uh, input sockets, they've actually manufactured that as a uh, complete assembly.

Look at that screwed down to the board. Not bad at all. They've even put the identifying marks on the PCB Nice attention to detail. Excellent.

There's some you know wiring attached directly to that. I Mean, check that out. Big beefy wiring going well somewhere. Does it actually snake under there? and is that the one that pops out? No.

they've got that going to there that looks like it. Almost? No. I thought it was I thought it. That was like a little bit of Cox sorry got it off camera there.

thought there was a bit of coax going across there, but it's uh, it's not and uh oh look, we have ourselves. Is that a no I Thought it was like Aista, but it looks like it's a tanum that they've just bent over on the board. Look at that. oh that's hilarious.

So that looks like a 16 mik tanum 35 volts. the um, the old uh dipped, uh tanum types and they are notoriously unreliable. They're horrible little beasts. There's a few of them, uh in here.

Looks like there's a couple over there as well. they are. yeah, absolutely horrible little things and uh uh. I'm surprised that it still works.

but look at that sucker. Wow, look at that. We have our um, that's our Transformer that's our DC todc uh converter Transformer that we saw on the uh schematic before that's being driven by Bfj 64 transistors there massive can package. Look at that.

ah, this is like really homebuilt stuff. Then we got some, you know, traditional uh carbons there with sort of like um, just uh, you know the brush painted on type. they would have just had the they spun the resistors on there and just painted that uh uh, painted those um color code rings on and then lacered them and oh man, that's just. it's just classic I Love it.

Look at that. Really old school stuff. Unbelievable. I mean you know it's not a thing of beauty.

Really, it's It's pretty darn horrible. And just below our sockets there, there's our big beefy 10m input resistors down there. Absolutely massive. That's our lead display standard.

D Pin out I Love the tape, uh, the taped artwork there just going connecting those displays up. Oh brilliant. That brings back lots of memories. Let me tell you.

individual uh digit, um, uh, driver transistors there in your classic, uh, plastic package there instead of you know these I don't know why they got these metal can packages down there. You know they're obviously power transistors and there's our fun function switch there. Look at that, you know all sort of, uh, all custom made PCB contacts down in there and the boards join together I mean I'm not going to take these boards apart I Don't think it's worth it? um I'm sorry, but I Really? you know I I really like this little uh uh, mold multimeter. It's classic and I'd hate to have to just desolder everything and rip the damn thing apart I don't I don't think it's worth it? um I don't know.

Maybe I'll run a poll on the Forum wants me to uh T strip the thing down and uh, really, you know I I can't see a huge benefit in that cuz uh, we can see. you know most of the uh, hideous Construction in this thing. but uh, I guess it wasn't too unusual for its day I mean you know actually Let's do an interesting comparison to my um old s me53 digital multimeter. this is the first digital multimeter I ever got.

it was a handm down when I got it and uh yeah, it served me well for many, many years. Unfortunately the screen is uh cracked now and I do remember but I cannot find this I'm going to have to go through my old collection of electronics Australia magazines. but I've talked about this before. this was the multimeter that Um was used I believe the same one that was used in a fluke ad of the time advertising the Fluke 70 series and the slogan was how to beat uh the high price of cheap multi and this was like it was beat up and it had tape all over it and all sorts of stuff.

So this was the cheap cheap multimet that fluke uh were comparing it to and um yeah I remember seeing that adding going oh almost crying because well this was my pride and joy back in the day I'm not sure the age of this. let's uh, open and find it out. I mean there's not much in there. this is basically a single chip.

um I do remember taking it out. it's like a single chip solution that does everything. but you know, really? um, old school, you know, end on resistors there. they've just used like an off-the-shelf um rotary switch? there? you know.

pretty crusty. Oh look, we have some Mo input protection. Wow. Stunning.

But uh yeah. I put some tape around there to pull the fuses out. Obviously some battery leakage there. but let's uh, that's you know this is like a big contrast in terms of um, you know the system integration in the sing chip multimeter.

but I think this is not um, too dissimilar age. so let's see if I can pop that off and have a look at the chip. Get a date. Here we go.

I got the sucker off. it looks like I had, uh, put some tape on there cuz yeah. I kind of remember that. that's uh I put some like plumbers tape on there I think because the uh, the shaft of that.

it was just one of those uh uh, fluted um shars and uh, it. my knob fell off and I uh I fixed it. oh Tada there we go. look at that.

Oh but um, yeah, I mean you know, streets ahead in terms of uh, integration and uh, technology and uh, construction and everything like that. By the way, this one had the unique ability to do uh, low ohms, um measurement as well so it wouldn't turn on a diode. Junction Really quite. uh, neat for its time.

and uh, there it is. there's my poor old saw multimeter. what's the date on that chip? 977 73 Well, I Can guarantee you that's not a date code cuz this thing wasn't manufactured in 1997 nor 73 brings back so many memories, so many measurements. and that's actually rather neat how they've mounted that uh, lead display board there on that angle.

They've just sort of done a cutout in that PCB there just W and looks like they've beveled it just wide enough for that to for that board to slip in at a certain angle. And if we have a look under the display board here I took off the two screws on top there. Tada there's our other chip and look, it's mounted in. um, those uh, freestanding machine pinned sockets? Look at that.

Oh man, it just. it gets boggier every time you look at this thing. Unbelievable. So that's the LD Triple1 down in there with the uh, Ld10 on the top.

But oh man. So there you have it. I Think we'll call it quits on this. Yugoslavian Multimeter.

But look at that. Have you ever seen multimeter construction like that? That is great? Oh man. Unbelievable. Anyway, thank you very much Silane for sending that in cuz that is terrific stuff.

and it's a Digima 10 Iscra multimeter. Now you know bit of Pub Trivia there name a 1980s vintage Yugoslavia Multimeter Ah That's easy. it's an Iscra and that is Cheapo Retro multimeter porn at its finest I Love it if you want to discuss it as there are many uh, vintage, Multimeter, Offici, and Idos on the EV blog. Forum That is the best place to do it.

The link to individual Forum threads for each video is down below that's down there if you're on YouTube maybe up there if you're watching on the blog. uh website if you watch the embedded video. if you're watching the podcast version, well, you can't link it anywhere. Tough luck.

You have to just type it in manually. and yes, I'll um scan the um schematic for this thing so you can take a look if you like. tear down Tuesday Please give it a big thumbs up. One thumb up, Two thumbs up.

I Don't care or if you don't like it, you can't give it a thumbs down. Whatever. Catch you next time.