Hi Welcome to the Apollo Launch Vehicle Digital Computer Video. Yes, this is the LV DC board from an Apollo Satin 5 rocket that took humans to the Moon Of course back in the 1960s. this was designed in the 60s and uh, this comes by courtesy of a fellow video blogger Fran Blanch and she's done some awesome reverse engineering. um stuff on this and uh, I'll link to her videos down below and uh, she passed this on to me to do something with and well, what am I going to do with it that uh, she hasn't already done well? I've got my A Precision Source measure unit.

So I thought that I'd measure some of these semiconductors inside here and see if they're still working after all these years. This was designed and built in the 1960s. So are the semiconductors still viable in these things? Do they still perform as Dodes and transistors? Well, let's find out now. all of this.

Apollo Hardware Of course was stadi Art designed to get humans to the Moon a very difficult task and designing the early computers like this. this was groundbreaking stuff that really, um, helped future uh, computer technology, manufacturing technology Electronics Ic's um, all sorts of things that we take for granted these days. A lot of it came from this sort of AP Poloo era. Hardware So really fantastic.

Legacy Stuff we've got here I Love it! And as the name says, the Launch Vehicle Digital Computer is basically exactly as it says this is a computer or part of it's one of the many boards that comprised the computer that controlled the Satin 5 rocket as it launched I.E the guidance and everything else as it uh, flew up and then was ultimately, uh, discarded. and there's a few of these are littering the bottom of the ocean of course, because, well, the Rockets just, uh, fell into the ocean I Don't think they ever recovered them or they might have recovered some bits from them or something like that, but this one never flew. uh, obviously, otherwise it would. we wouldn't have it in this sort of uh, condition.

And yeah, it's not in great condition because Fran's already done some uh work on it. She's depotted some of these chips and here's a photo of uh, actually depotting these things. It wasn't pretty. They had a a pink, uh, sort of, you know, a epoxy type putty inside with a ceramic top and these, uh, these chips actually slide out from these uh little uh, Clips based on this board and it's a very complex, uh manufactured board for its era.

I mean obviously absolutely state-of-the-art for its time and this is not a chip as you know them today. This is a basically just got diodes and transistors in them. It's Dtl Diode transistor logic and that's pretty much it. But we do actually have a data sheet for a couple of the these chips, so we do actually know the pinouts so we can test them now.

You can hopefully see some of those clips there that held in these chips and I'll basically just slide in like that. Look at those Vs I mean that's uh, you know, not unlike what you don't see these days. but the uh, construction technology of this board is very significantly different to uh, what you'd uh, see these days on a board, but on a physical. you know, typical printed circuit board these days.

But anyway, look at those clips. Yeah, there's a lot of corrosion and Gunk and all sorts of stuff on these things. but hopefully, um, we can probe some of these things and or slide out a couple of these chips because we've only got data sheet on a couple of these. uh Parts.

But we do know the pinouts so we can slide them out and hopefully still be able to probe the Metalized pads on the side of these things. So right down in there, we got a a slight amount intact I don't know how easy that's going to be. Fran has actually done it. So uh, yeah.

Well, I've got to give it a go and I've only got a couple of shots at it so well, fingers crossed and whether or not we can still make contact to the Metalized uh pads actually on that uh, substrate material now I Have actually had a bit of success probing the back here and even before I got the data sheet from Fran I was able to probe out a couple of uh, what appeared to be PN semiconductor Junctions I.E Dodes um inside this thing just by random uh probing and you'll notice that there's no traces on the bottom at all. These are all. it's all internal layer stuff. So incredibly complex.

Uh. construction. This is a very multi-layer board and uh, as I said, you know pretty different construction techniques, but not too dissimilar to the overall uh structure of what you get in a PCB these days. But yeah, nothing on the bottom whatsoever.

It's got this sort of covering on it I don't even know what that covering is, but we can actually chip that away. It's all been chipped away from this area down here, so we'll just see if we can get a just a closer up version of this board. I'll switch on my Tagano microscope here and let's go to the videotape. All right here we go.

It looks fantastic under the microscope here, and here is the top view: internal uh diagram of what's inside this Inver uh inverter module Here Imv we only have the data sheet for two of them, the uh inverter and this What's called the AA chip here. So I've only got one inverter on this whole board so fingers crossed and two AA chips like this. and of course we can't measure them um in circuit because we'll get errors due to however, it's wide inside. uh, you know.

So really, we have to try and get the chips. Slide them out of these connect Ctors on here to try and access the Uh pins on these things. And basically that's the Um. internal circuit diagram.

We've got one transistor, two backto back uh, Dodes here, and some, and some resistors. That's pretty much all that's inside this inverter module here. and this is why they call it Diode. uh, transistor logic Dtl because it uses Dodes and transistors and pull up resistors and it forms your Gates and your logic that way.

So there you go inside that one. And the AA module is even simpler than that. Doesn't even have any transistors here. We go these AA modules here.

just a couple of back common, uh, back, anod. common backto back dodes like that. going out to separate pins there with a 2.5k pull-up resistor and what we can do is, uh, zoom in here and take a look at a couple of these chips that Fr's already depotted for us. Look at that.

oh I Love this Tagano microscope. Very nice and uh, this one still has the chip in it. Look at that, you can see the chip there. and physical these two pins physically connected.

That one's going off there, so that looks like a three pin device. These have, uh, she's obviously, uh, accidentally or purposely ripped out the chips from these two here. And you can see some of that uh, potting compound still still in the corner down in there. Look at that.

That's terrific. Can I zoom in any closer than that? That's the the maximum. Zoom I can get on this Tagano microscope. but yeah, look at that.

So it was potted with that whatever material that is I Don't want to know. Um, but you can see the Metalized traces lay down in there. Very very interesting and if we angle that we can really see those those clips there, check it out and it is horribly corroded and rusted. but uh, hopefully can slide out these chips and then probe what's left of the metal.

You can see parts of the Metalized contact still on there going inside the chip and then they' then there got this wall around it with a ceramic top on it and then they fill them with that potting compound and these clips are somehow uh, welded onto these uh Metalized pads down on the board. Interesting construction technique and check that out. We can see down some of the Vs in there, look at that, see the wall of those. and as I said, manufactured in the 1960s.

State-ofthe-art technology. Awesome Shame it's not in better shape. but anyway, what do you expect? And there's some of the Vas on the bottom side and look at this bottom, stuff looks quite fiberg glassy. so yeah, it's something like that.

It does peel off relative ly. Okay I have chipped away a little bit of this and it does does seem to come off. It's a bit easier towards the outside parts of the board, but uh, as you get in, gets a bit more difficult so it certainly is very interesting technology. I Love this stuff and uh, no date code on this particular model I Can't remember if FR actually was able to get a date on this one or not, but uh, that folks is 1960s Apollo Technology Ah, you got to love it Now it actually doesn't seem hugely difficult to clean up some of these pads here.

I'm just using some isopropanol alcohol here and uh, that's cleaning up. Not bad at all. Check that out! I Rather like it there you go. Look at that like a bought one now.

I Do know that this was state-ofthe-art at the time, of course, but I Can't help but think why didn't they integrate this further I mean these chips that have got basically Bug roll in them an entire chip taking up this and well, presuma. I Don't know what the some of the other chips in here do, but say the inverter for example I mean you know we've just got like a couple of Dodes and a transistor in there. Why didn't they uh, you know this little um, piece of silicon down here? well why didn't they just make it a bit l I Know the Silicon manufacturing technology back then was in its absolute infancy, but and this was you Know pushing the state-of-the-art technology. but it just I just can't help but think why they just didn't pack more functionality into one device like that.

I mean it's not like they had this, you know, gigantic Dy in there to do a transistor and a couple of diods I mean look, you know that that dying there is just one device. Why couldn't they just pack more of them in there and and utilize all the pins? I mean you know we've got unused pins all over the state I Know it's like designed to be modular and things like that and they have you know, specific chips for specific purposes. but why they just couldn't do more and I don't know it, just it just seems a bit limited to me. but eh, you know I mean the uh, the constraints of the time.

They probably designed this much much earlier and then as technology improved they couldn't. Just you know. Wham Let's just change it all, you know, 5 years into the Apollo program or something like that. So really, they'll probably stuck with what they had and eh, it was good enough.

It did the job and what we've got here is an Agilant B291 TOA Precision Source measure unit or SMU or Schmo as they're known and we can use one of these to test the semiconductors to and actually characterize their voltage and current performance. I. get those characteristic curves that you see in the data sheets I've done a tear down video on this if you want to see it. It's really interesting Beast inside Very expensive thing and unfortunately I've only got it for another uh, day or two so I've got to send it back.

but hopefully we can probe some semiconductors here see if they're still usable. Let's go now. I Won't bore you with the details of how exactly Schoo work and how to set them up, but uh, we'll start out with just measuring a basic modern 1in 4148 diode here and this is what we get. So then we'll have a baseline of instruments set up to work against to uh, characterize the diode performance inside these Apollo era chips.

So here we go. if we probe it and we press measure, Boom, there we go. We've taken 100 sample points and we get our characteristic diode curve there. It is starting to ramp up at about 0.6 volts here, going all the way up.

So that's what we'd expect of a typical Uh diode from the Apollo era as well. I mean you know, the voltages and currents and everything else might, uh, change a little bit, but we basically expect that PN Junction characteristic curve shape and what I'll do is I'll use these uh, really fine pointed springy probes here so they can get decent, uh pressure down on just the individual pins down in there. so I'll be able to probe hopefully and get through any uh, oxidized, uh coating on those pins or anything like that. So I'll start out just by trying to measure one in circuit on that inverter chip.

Well looking what we have here, it's a similar sort of characteristic curve, but not nearly sort of the Voltag as we expect. I got five 0 to 5 volts on the Xaxis here, but it does actually curve up like a PN Junction I measured this one in Circuit of course. um, just one of the diodes inside the inverter chip and you know it's from zero to 50 milliamps is the test currents I put in and well, we're getting huge. You know that's a large voltage drop across these diods.

I'm not sure what uh, we would expect for the era, but you know they've got to be like, you know, silicon or Geranium technology or something like that. So I wouldn't expected anything like that. I would have expected it to ramp up. you know, similar to what we uh, saw before.

at least you know, maybe a vault or something like that based on the current. even. you know, a vault and a half something like that. So that seems grossly out.

but that could be because we're in circuit. We got one. Yes, Check it out. I Probed pins.

Uh, one and eight. here. Here we go pins one and eight of our uh inverter chip and this is what you'd expect. This is a Dio characteristic curve starts ramping up at a silicon Dio characteristic curve starts ramping up about 0.6 exactly what the modern 1 in 4148 does.

and at 50 milliamps okay, we've got 1.1 volts drop. Okay, so it's not a particularly High current diode or allw but that Bingo it doesn't maybe that is not connect connected to anything else in circuit and we have ourselves a a classic Dio characteristic curve there. This chip still works. the semiconductor inside still works after all these years straight from the 1960s.

Beauty What a Bobby Desler. This actually works I Can't believe it. So if we probe these again, it really is rather a bit tricky. I've got to sort of hold it with two hands like this and get the tongue at the right angle.

Here we go, tongue's at the right angle and there we go. It is really quite tricky to get the contacts right on this thing. and yeah, look, you end up with like little Wiggles uh in here like this. if you don't get the uh contacts right, I'll uh, print, screen that and show you that one up close and yeah, you get these awful little Wiggles in there and uh, stuff like that, you know, just through the um, you know, at the microscopic level of how you're actually probing.

these things gives you all sorts of weird and wonderful stuff. So you really got to use these um, really sharp probes. and also the ones with the pressure. uh with the spring loaded ones as well.

Really? uh, quite help to you know. try and Pierce these things and keep an even pressure on that joint so can get it though. Fantastic. Well, this is a bit of a Wimpy test.

I think we're only talking like 0 to 50 milliamps. I'm testing this thing out. This is capable of uh, a couple of amps at hundreds of volts. so let's ramp it up.

so I'll ramp up my current limit. Here we go. Uh, start from zero amps. it's going to go up to 1 amp in I've got like a 100 steps in there, which is, uh, more than adequate to get the resolution on our graph and a compliance voltage where it'll cut out at 10 Vol So let's give that a bur.

if we break it, we break it. Wow, look at that. That's a rugged little bastard isn't it? Look, one amp and uh, we ramped it all the way up. didn't blow at well, presumably I haven't run it a second time.

Those Wiggles as I said are just little, uh, contact, uh, issues in there we can't actually get it to do Straight if we uh uh, probe it well enough. but yeah, it basically still ramps up at that 0.6 Vols and then basically completely linear region right up here. Yeah, sure, we're getting like a 4, uh, 2, or 4.3 volt drop at an amp, but gez, you can't blame it. Nice.

let's ramp it all the way up and I've gone for these beefier probe Master probes for the higher currents. Once again, these are incredibly sharp tips, but they got no, uh, spring point on there and they got nice finger grips on them. so I can really get in there and probe the pins like that. solid and this is what we get.

and I had a compliance voltage of 5 volts here, so that's why it's crapped out there. but you can see how we had that linear ramp before. almost linear sort of St to tape off a little bit as it approaches 1 amp there at 4 Vols and then it really starts to tail off. So we're really losing the nonlinearity of the diode here.

So really, its operational range sort of seems to be like, you know, not even an amp, maybe sort of. you know, to be conservative I'd say probably, you know, like a half amp rated diode or something like that. So as you'd expect, these things are designed for low current. You know, operation cuz these are a computer.

they're you know, working in the order as we saw on the schematic before order of like, you know, several K to sort of tens of K pullup resistors. stuff like that. So we're really just pushing this thing silly to see where we break it at the moment. It's not really a half amp or 1 amp operational diode, that's for sure.

And there we go. Look at this. This is interesting I changed the compliance voltage to 10 volts here. so um, it's still I'm ramping from Zer to 1 and A2 amps here I stopped at 1 and a/2 amps and look at this.

Here's a what we saw before with the sort of the one amp curve like that and it starts to taper off as we saw. but then it starts to taper back up. Look at that. so there's some weird characteristic going on there.

Now it's actually better off if I don't kill this thing. So what I'm going to do is I'm trying to going to try and slide out this uh, inverter chip here. it's the only one that I've got. so I've only got one shot at this.

So basically I've got to remove uh, several of these other pins around here just so that I can sort of can I get the iron in there and yep, yep, no problem whatsoever. So I can get rid of these and uh, that'll help me slide it out of course, otherwise they will be in the way. This is not elegant by any stretch and uh, not recommended for repairing a Poloo era boards. This is not an approved repair technique, so please no uh, flame emails or comments and there you go.

There's one of those little Clips designed to like welded. The bottom part of that was welded onto the board in some way, shape or form and then uh yeah, they were just designed to clip into those modules so that has seen better days. and here we go. What I want to do is I'm going to try and sort of lever it under this end and slide it out this direction.

And the good thing, what I was probing before was actually probing pins uh 1 and uh8 here. Yes, they're not labeled in the usual way, but that's what they. well, the modern way we're used to here. but pins number one and eight.

so I really only have to slide it out a little bit and then it's not making contact with there because the idea here is just to slide the chip out. So then we can possibly get access to the top of those pins in there without having it in circuit. I just want to rify that uh Di in there that PN Junction just absolutely sure it's not in circuit and here we go. it's time to brutalize it.

Yes, this is awful. I'm getting my screwdriver in here, but I just want to see if it budges. It does budge, look does budge. I'm probably going to I might destroy this chip here, but if I can slide this puppy out, Yeah there we go.

Slid in, slide in. Maybe if I come in this angle and Tada we're out, we're out, there. we go. That's good enough and I should be able to now get in there and probe if there's any of those pads left.

I don't know they I don't know. Presumably they was just like press fit on there, but who knows. they may have corroded off. So hopefully well, we'll see if we can get in there and access.

you can see. this top one has some metal left on it by the looks of it. not entirely sure about the bottom one. It could just be more looks than anything.

Oh well. we'll see if we can still probe it if we can't Oh well. and yes, Bingo we got it. Look at that.

It is basically exactly the same as what we got before ramping up at about you know, 0.7 volts or thereabouts. and uh, sort of half an amp we're looking at like, you know, 2.2 Vols or something and then ramping up to an amp I Didn't take it any higher than that at this stage and you can see it tapers off there so that one was pretty much, uh, if it was in circuit. there really wasn't uh, any major effect there on it. So that is the characteristic curve of a 1960s era.

Apollo Uh chip. One of the one of the very first uh semiconductor chips ever made. Fantastic. And yet there we go.

I ramp it up to 1 and A2 again. with we get exactly the same as what we got before that little contact wiggle in there and uh, that's it. So that's the characteristic curve going up to 1 and 1/2 amp grossly overloaded to what this thing was designed to do. it's that's a bit mean.

And there is. the chip actually fully removed there and we can see the bottom of that Here we go. Nobody's seen the bottom of that uh chip since it was installed back in the 1960s and it's got some sort of uh, sort of, you know, pain or some sort of epoxy type base on it. and I tried to measure some of the other internal resistors in there to see if we could get a linear uh response out of and I couldn't get anything.

It's like there's no internal contact in there at all. I Tried three different resistors and couldn't get any of them. It was just flatlined. Uh, I couldn't get the linear slope that we expect out of a resistor.

but I've actually done this uh, previously. probing around in circuit and I did actually find one on the board. I just can't find one in this inverter. So let me show you the one I found previously.

So according to my notes, Here uh, that pin there and that pin there and that one and that one over there should be a to both of those should be 4k4 resistors and here we go. This is really easy to probe the back here. it just goes straight down the V holes nice and we'll measure that Bingo there our straight line characteristic curve of a resistor that's from 0 to 10 Vols Completely linear. Exactly what you'd expect from a resistor.

I Can take that to higher voltage? Why not? I Feel ashamed to do this to a classic Apollo Eara board. but here we go: 0 to 100 volts on this poor little resistor. Let's go ah out of range What Fail eh. Unfortunately, this bloody SMU has got got an interlock uh circuit on it so you can't go over 42 volts on the output unless you uh, connect some digital interlock thing and I read the manual.

It didn't give me pinouts for the connector on the back where I have to connect the interlock and all that sort of garbage. Ah well. anyway we went from 0 to 40 Vols and it's completely linear right up to 40. Awesome And well to get back to where this thing is realistically used I mean 0 to 20 milliamps for example.

look I mean classic diode characteristic curve. Perfectly fully functional diode. even today. even at 20, you know, 20 odd milliamps about .9 Vol Uh, drop down at 5 milliamps here.

only about, you know, 77 volts drop or something like that. Perfectly adequate diode for then and now. Really? Yeah, it's not crash hot, but for the just the signal operations that they wanted this for. uh, Dtl type stuff.

Diod Transistor logic, computer stuff. and if you're curious to know the leakage there there, no basically buger all. of course you just put the diode in Reverse From 0 to 10 volts there, it's you know, basically like in the order of 0.1 microamps. so pretty much on par with a 1n 4148.

So there you have it, that's a 196s era. Apollo Launch Vehicle Digital Computer Logic Board Fantastic. And the dodes and resistors And you know, the deposited resistors and everything in here still work. and they're still functional.

Fantastic. So you got to wonder if you kept these things in pristine condition? Those uh Satin rockets that are still? There's a few of these still sitting inside the satin. Rockets I Believe that are inside the museums that you can go and see the remaining ones that they actually built. They would probably good chance that the majority of them would still work today.

Uh yeah, you'd probably have a few issues. You might have to swap a few boards or something, but hey, that's pretty awesome for 1960s technology. I Love it and that's a perfectly usable Dio characteristic curve. uh yeah, sorry.

I Don't have the uh, time or uh, anything to measure the transistor inside this thing. It was hard enough. Get in the damn. Dio But the deposited resistors in here perfectly fine and linear diodes.

Fantastic. so it still works my thumbs up to two thumbs up to the Uh Apollo era designers who pioneered all this stuff we take for granted these days. and this is one of the world's first earliest you know, uh, fully integrated, uh digital, you know? IC based computer I mean amazing. They've only got a couple of Dods couple of transistors per chip.

Now we're talking. You know hundreds of millions of transistors per chip is just in our phone and in our watch. It's just crazy stuff. But anyway, thank you very much.

uh Fran for loaning me this fantastic vintage board and the idea was to pass this thing around to other people to do other stuff with. So I think you know I've done my little part I've used my source measure unit. Sadly, this has to go back to Agilant in a day or two. and uh, yeah, so we confirm that this thing still works or is still viable today.

Fantastic! So if uh, you want to want this thing, I'll pass it on to you. and if you got an idea of some videos you want to, uh do, of course it has to be made uh, public. all the info and uh videos of it. but if you do, if you want it, please contact me.

Thanks! Fran and I'll link to Fran's uh videos and her blog page down below as well. And she's got a new uh podcast, uh thing. a new uh video show happening with Bill uh herd I believe. So check that one out too.

it'll be linked in down below. Catch you next time! Um.