Hi Welcome to a Mystery Teardown. Can you guess what this is? I'm not going to tell you I'm going to open up and let you figure it out for yourself. I've covered up the brand name here because you might recognize it. We've got a line on and off status, start/stop It's obviously in a 19-inch rack mount.

There's some sort of channel label thing over there and if we have a look on the back here, this is what we've got. Just got a card edge connector here, some weird-ass input and output system, I/o connectors, a remote start made in the United States of America and an IC input thank God Any ideas? Now the interesting thing about this. as though it's from a massive name, which you can find almost any information on any product they've ever made. But my Google foo must be off cuz I can't find a single thing about this.

No user manual, no specs, no schematic, no service manual, nothing zip nada. Which of course makes it all the more interesting. So let's go. Yes, this is my new Electric Speedy Screwdriver.

Here we go. let's take a look inside. your guess is as good as mine. Whoa.

Okay, we've got some as that seven, four series stuff. No, it's not. Well, it could very well be, but they're custom part numbers and you might recognize the logo. HP None this Agilent rubbish and certainly known this keysight rubbish.

We've got a bit of HP kit. can you still figure out what this is? We've got a mysterious metal can down here with our cottage connector. Awesome, gorgeous looking sprog capacitors for U S-- Pride fanboys 2600 mic. None of that like 2200 E/12 type rubbish we've got.

Looks like some power train is down here on standoffs and maybe some, you know, dinners and diodes. And and as is common in HP gear, you'll find the custom part numbers. No leaks. could very well be like you know, standard 7, 4, or 4000 series CMOS chips.

but they've all got the HP part numbers on them. Very, very common. We've got a couple of relays got a mains over there and you know it's pretty how you're doing wiring down in there as well. Check that out.

Jeez, that's kind of like an HP isn't it? It's almost as if it's like it's you know, not like a mainstream product. I've got what looks like a To3 package down in there. probably like a series pass transistor for a linear regulator. and now that switching rubbish in something like this, you still got any idea what it is.

Beulah Beulah and do believe under here we'll have some sort of adjustment. something. Come on, ya know what? Some sort of like wall like? it's not foam. It's not like closed cell foam.

It's more like some sort of woollen stuff. Weird. I Expected to find a trimmer pod under there. The plot thickens.

In fact. check this out. The entire thing look is mounted on this rubber. sort of.

It's it's almost sticky, kind of sort of foamy rubber. backing on that. so so that's really strange. Let's take a squiz inside.

Okay, a socially let's lift. Does any know there might be might be something on the bottom? I think I've got to get there. It might have to get the whole board out first. and I don't know that's what's going on, that's probably Japanese Relay Fanboys Babcock Let's have a look what's under this board here.

More stuff. Oh Motorola Crystal Oscillator upside down so all the Jon's are gonna fall out. Look at that. We've got some potted little custom transformers there with like you know, half a dozen turns on each side.

So Wow anyway, it's running at massive eight point, three, eight megahertz. Fantastic. But once again, got all the HP part numbers. You can go look those up, but you know that's this signetics stuff like that.

Do we even have a date code yet? I Don't know. Oh, you're the burn marks around that Diode bridge there? It's got a bit warm ski and these little jumper pins here in the little machine pin socket. that's pretty how you doing. Um, this is very unlike HP It's almost as if it's not a mainstream product.

that's probably why I Couldn't find any information on this thing at all. Oh oh look, it's a little odd that there must be a channel thing I reckon that's a channel selector and it smelt like mid-70s to me. And sure enough, 47th week 73 and 23rd week 73. What do we got? 27th Week 74.

So yeah, it's actually yeah, it's mid 70s. The smell is bang-on So do you have any clue what this thing does yet? Well, actually I was wrong about the channel select up here. It's not channel select. If we actually go, have a look inside here.

Tada, this might give you a clue. Rd GS per second readings per second. We're currently on four readings per second. Can you guess what it is now? Beulah and I Just love the hand taped layout on this.

That's just classic. Look at that. Somebody's gone along there with the bishop tape and laid out that double-sided board. Brilliant! I Found one that doesn't have a HP part number on it.

7404 Hex Inverter 7410 Is it? Oh sorry, 74 10. but everything else has HP part numbers on it. So I'd actually say that's your address select down there. Yeah, One, two, four, eight.

just select your address in binary. Does anyone remember Stephens Arnold Inc in South Boston Massachusetts That or the go-to in the mid 70s for isolation transformers by looks of it. Wow look at the burn marks from that bridge rectifier. Anyway, all the magics under here have you figured out what it is yet? by the way.

And I love the PCB threaded screw eyelets in there for the power. That's just fantastic. Don't see enough of that these days. Oh no.

I don't think they're They go all the way through, not the screws were holding them in. We just have to get a bit medieval on its ass. and oh, it's dead wrapped in plastic like that. Well with this like look like that's like thermal insulation.

Look at that just like you would. You know your pink bats, your woollen bats that you get in your house roof. Terrific. They want.

Really wanted to keep this at not probably not at a fixed temperature because I don't see anything in terms of like a heating element in there. It's not temperature controlled, but they do want to thermally isolate it so they don't want any drafts drifting across here and then upsetting components. Because we've probably got you know, match transistors in here like this and there. You know these too much.

they look like wow, they look like precision resistors. Whatever. closer look at this. This is fascinating.

Don't you hate it when you've got woollen hair stuck on your capacitors? So yeah, they're obviously don't want any drafts coming a cry. Evan Though this thing doesn't have a fan at all. Um, you don't want any, you know, convection inside the case. Just you know, any temperature gradients across your components.

So there you go. There's all the magic. Can you guess what it is yet? Should I tell you? Should I show you the front panel label. Mmm.

Looks like it's conformally coated. You can see the shine on that compared to the PCB probably to stop moisture on the PCB So whatever this is, it is a well. high precision for the time. High precision something-or-other All right.

I'll put you out of your misery. Tada Hewlett-packard 1865 to AE Analog to digital converter? Yes and none of this single chip or built into your microcontroller. ADC Rubbish, No siree. Bob This is obviously some sort of, you know, precision analog to digital converter for some like.

because I can't find any information on this. It leads me to believe that it's probably some like industry specific thing. Maybe they're you know, the medical or research industry or something like that. You know physics stuff, things like that, physics, divert sampling, or some other such thing that they're It's not like designed for one customer because there's a lot of these around.

You can actually still buy these secondhand on eBay so there must have had a lot of use. but I can't find any information on the HP 1865 to a at all. So maybe my Google food just sucks today. But anyway, this is an ADC I don't So I don't even have any specs.

What is it? Maybe it was a like a 16 bit ADC for the day or something like that at you know, four samples per second. Maybe it was higher than that. 1820 could have been 24 bits at the time, who knows. but they certainly went to a lot of effort to do this.

Oh, they rub the numbers off. Oh no, no. I Thought they'd rub the numbers off. Here you go.

we have part numbers on those. Wow. I Haven't seen one of those packages in a long time. It looks like your standard transistor, which you'd get here.

of course, your standard RTO 92 package there, but then it's just got the round base on it. Old-school Wow Check these out! These are fascinating. These are precision resistors. Circuit trim IRC circuitry 10k resistors, but you can see that they're only plus minus 5% there there.

you know, low tolerance resistors on the 10k and 5 k plus minus 5% but they would have a ridiculously high temp Coe those things. so they'd be really schmick resistors. Probably paid a fortune for them. Maybe though.

I Will they laser trim back in the day? or they, you know, trim by nude virgins with gray beards? I Don't know. But yeah, Precision resistors. Awesome. And there's nothing on the bottom, but it looks like they do have that dark conformal coating on there as well.

just to stop the spread of moisture across the PCB So to stop any creepy to cross the board, once again, they've got that foam insulation there just to stop any temperature gradients across the PCB Nice. So you think this is like maybe a multi-channel wire a DC but note that we've got ground on the bottom there and just the single input on the top. That's all she wrote. so it's a single input.

a DC Obviously high resolution, high precision. It's got our one volt input range and the readings per second. You know you can choose from half a reading per second up to 32 I Presume that would maybe trade-off the bandwidth and/or the number of bits as well. Maybe you can a higher sample rate? you get my greater effective number of bits.

So I Don't know what topology they'd be using? Some sort of like you know, is it a single or dual slope integrator or something like that? Perhaps. But yeah, it's a custom ADC one channel ADC in a 19-inch rack for some ridiculously specific market may you know, probably cost thousands of dollars back in the 70s for one of these analog to digital converters. If anyone knows the price of this, the specs of this, Anyone's got a schematic or anything like that. you know, please let us know.

Even like a manual and like or some sort of data sheet for it, Please let no, because it's fascinating. That's 19-inch rack. a DC Did anyone guess it? If you did, you win the Internet and I'm going to assume that this is our like a sampling capacitor. here.

these electrolytic wouldn't be of course, but you know I've got some other schmick oh film ones in there. that could be. So it's got to be some sort of you know sampling ADC And then everything else is. you know, maybe timer counter stuff.

Yeah, interesting because it's certainly not like you know it. It's not like analog comes in and digital comes out of that can. That's not what's going on there at all. So anyway, this is the power supply side of it, obviously.

so this is is your main filter caps here. Then we've got some. maybe some series past here, maybe some lower like some secondary regulation there because there's precision ADC Like this one, it's got to have nice regulated supplies, so these are all probably local regulation for it. and then you're some sort of Sloopy ADC integrator and then all the rest of the stuff to convert it to digital.

and then there's you know, probably shifts it out. Well, is it parallel out or is it no. it's serial out because on the back has just got output and input so you can cascade them together probably. and it probably shoves all the data into one bigger serial stream or something.

Yeah, it's measure some voltages here. I've powered it on and we get the red status light and the relay up there goes clunk clunk. so something's happening. so let's measure this plus minus 15 volts in here.

Whoa. 22 22 So it doesn't sound good. Let's measure the 5 volt rail. 5 volt rails.

Good. So all the digital stuffs going to be doing its digital magic. Maybe they've mislabeled on the PCB in there at plus minus 15 and plus minus 22 is the go for that. All the two regulators could be shot I Don't know if we got positive negative regulators in there, they could be Gonski And that's our five volt rail there that looks reasonably good.

That's 5 millivolts per division and well, what's going on there? Well, I thought it was good. No whoa. Jumping around the shop. that's 50 millivolts per division.

And why is it banging around like that? Wow that's a sick puppy power supply. Hate the stupid Larry screen on this new you ride all 7000. Well, and that's our five volt rail. Wow, there's some stuff happening.

start. - look at all that high frequency crap happening in there. Wow, that's not. It's not a happy camper, is it? Ok, so I've given that ROI Go 7000.

The flick that screens just horrible. All right. I'm gonna single-shot capture one volt per division. I've got the serial output here.

which is you know the output has just like this. adjust the output. There's an input and output connector as you saw right at the start. I'm gonna press Start here see what happens and single shot.

Tada looks like we have something. It's decaying. Whoa. what's going negative? Hello! Ok, we're getting stuff here when I press it.

Let's actually go into roll mode shall we? And give it a go now. I'm gonna press the button. Boom! So here's a single. looks like it gives a single pulse if I hold it down and let it go.

for hold it down. it goes negative. if I release the front panel start/stop button, it goes positive. That's interesting if I keep pressing it.

it's just that just doesn't seem right I Expected some sort of serial data packet cuz the 5 volt rail is working. so even if the analog section was crap I'd still expect it to be doing the business so you know it's got that 8 Meg clock in there I expected it to be. you know, outputting a stream of data. So but it ain't could be.

we're just one sick puppy like I said if you've got any info on it at all I cannot find a damn thing. The specs use a manual, a datasheet, anything on it at all. which is quite strange. which leads me to think that it was, you know, developed and and sold by one of the you know, specialist divisions of Hewlett-packard like spun off once our keysight focused on test and measurement and stuff like that back in the day.

Yeah, they had just all these different divisions, so some sort of like, you know, maybe research type analog to digital converter. I've got no idea I just I got my dear' of the specs, but it's obviously precision. They went to a lot of trouble with that. They're thermally inside this thing to match and I make sure there's no thermal gradients across those components which can upset the Applecart.

In terms of you know, the balance of you, the symmetry of your circuit in there when you got matched. That's why you often use matched transistor pairs in the same package on the same die because they're at the same temperature. That's why Often you'll get two transistors and back in the day still rarely. but you see it occasionally these days two transistors back-to-back and then they'll bond them together with a piece of metal to keep them thermally matched.

So yeah, they've gone to a lot of trouble to do that, and it's some sort of mystery analog to digital converter. anyway. I hope you found that interesting. If you did, give the video a big thumbs up.

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