Greeting earthlings. If you follow the channel, you know that we love all things Apollo,
and that we have been working hard at making some of the original spacecraft electronics work again.
And we’ve had a pretty good success so far, getting everything we could put our hands on
back into operation, like the Apollo Guidance Computer or the Apollo S-Band radio equipment.
Usually, we start by opening up everything we can for inspection, reverse engineering, and repair.
And what we see inside never fails to impress us. But sometimes, we just can’t do that,
because the flight-ready modules are potted or just welded shut.
But today, lucky us, we are going to be able to look inside some of these,
thanks to the incredible new X-Ray tomography machine
from startup Lumafield. Jon at Lumafield reached out to us and graciously proposed to assist us.
We of course jumped at the opportunity, and brought some of our most mysterious Apollo items:
my newly acquired CTE box, which is welded shut and whose insides are completely unknown,
my Apollo IRIG gyro, also welded shut,
two potted PSA modules, one of them with obvious damage, and another one of the
mystery Motorola modules from the Uplink Data box that we revived in the previous episodes.
And even better, the Lumafield 3D scans will be made publicly
available for you to explore on your own.
We can’t wait to see what’s inside!
[Jon] Yeah, this is the scanner. It works on the same principle as a medical CT scanner,
though different mechanical configuration. So in a medical CT scanner, an x-ray source
and an x-ray detector rotate around you. And in an industrial scanner, the part rotates
between the x-ray source, over here, and the detector, here.
So you run a scan, it uploads the sequence of two-dimensional x-rays
to the cloud, and then our software reconstructs it into a 3D image.
[Ken] It seems very easy to use.
[Jon] Yeah, the idea is making it accessible, making it into something that
that a lot of folks could use as part of their product development process.
So what would you like to start with in the machine?
[Marc] Well, you tell us.
Since they are all metal encased, except these three ones, are we going to see something quickly?
[Jon] Well, we'll see the two dimensional scans. And so what I suggest is,
I can put all of these in, we can look at the two dimensional x-rays immediately. And then,
if you're comfortable leaving these for a few days, we'll run long,
kind of overnight scans, to get high quality 3D results.
All right. First up, a new arrival, my Apollo Central Timing Equipment, or CTE
box. This is the clock of the spaceship, and we know relatively little about it.
We do know it works, because we already turned it on, more details in an upcoming video.
We know it generates an 8 bit parallel BCD code for seconds, minutes,
hours and days, and a serial code with the same information, and all that appears to work.
We have some block diagrams revealing it should be a clock PLL and dividers,
mostly. Should not be that complicated. Or is it? Remember when we looked at the
Soviet Soyuz space clock, it was way more involved than we had expected,
despite being from much later and using ICs. So maybe, after all, it won’t be that simple.
It fits huh, barely.
[Jon] It at least sort of fits.
So we'll turn on the x-rays and then it takes a moment for the x-rays to stabilize.
[Marc] Are those prototype units, or are you in production already with those scanners?
[Jon] For the scanner? [Marc] Yeah.
[Jon] This is in production, yeah.
[Marc] Oh, excellent.
[Jon] The one back there is a prototype unit.
[Marc] Oh, we see already!
[Jon] Yeah, we see something.
[Marc] Oh my!
[Ken] That is nice!
[Marc] It's like, transparent!
[Jon] Yeah, so I think magnesium is pretty easy for x-rays to look through.
[Marc] And that's after, like, few seconds.
Whoa! Definitely much more complicated than expected.
You can already tell this is an unusual combo of PCB and cordwood construction.
[Jon] The idea is that, as the scan progresses, the turntable is rotating.
It'll be something like 1000, 1500 individual incremental two-dimensional x-rays. So you're
seeing it from different angles, like this. To get a high quality reconstruction of a part like this,
with a wide dynamic range of materials, we would run it sort of overnight, like 12 hours.
[Marc] OK.
One week later...
And here is what we got after the full scan. These are the original x-rays from which the
3D reconstruction is performed, which we’ll look at in a minute. This, by the way, is Lumafield’s
viewer software which runs in a browser, so anyone will be able to explore the data, like I will do
here, once we link it in the doodly-doo. So I can adjust the contrast a little bit,
and this is basically what a normal multi-angle x-ray would do, which is already not bad.
But the fun really begins when you switch to the 3D computed reconstruction.
So let’s fire up the elevator music and spin it around a little bit.
So now that it’s 3D, we can cut through it, here we go, top to bottom.
We go through the connectors, the wiring, I'll explain more of that, some of the PCBs.
All kind of components, it's very full in there. And finally you can
see the big transformers from the power supply.
And of course, same thing in the other direction.
Let’s look at this in more detail. First we notice the two fill valves that stand out
prominently. These are used to pressurize the unit with dry nitrogen. But the left
one also doubles as an adjustment port for the oscillator frequency. More on that in a minute.
The end view clearly reveals the cordwood sub-modules with components going vertically.
Here is the outline of one of the cordwood modules. The PCB boards between the modules
are just used for module to module wiring. We can also see plenty of resistors and caps.
But what’s this row of rectangular things over to the left? Yes, they are ICs. I was
quite surprised, I thought only the AGC had ICs in the Apollo spacecraft. But the little
documentation we have implies that they have used ICs to implement some functions in the CTE like flip-flops.
Here you can see them better. The cylindrical things with rounded end caps are carbon resistors.
Here you can see more ICs from the side, and we can see how tightly packed the cordwood
construction is. Which is mostly why it was used. Of course, we see many transistors in
metal can packages, the round things with the three leads and the little tab on the side.
We also cut through the power supply transformers at the bottom.
More views through our densely packed ICs, and electronic components. The array of cylinders
at the right look like an array of diodes, probably for diode-transistor logic gates.
But back to our inlet valves. We know that one should provide access
to fine frequency tuning, and you can see that it is aligned with another cylinder in the module.
The alignment is particularly obvious on the planar slice view to the right.
So because of that, I have a good guess where the temperature compensated oscillator module
is. It should be this module there in the corner. Which gave me an idea. Could I see
the quartz crystal in the x-ray? I mean, not only the case, but the crystal disk itself?
Judging from the other crystals we found in Apollo hardware,
it should be quite large and look like this.
And sure enough, there it is, we can see the large case of the crystal.
But can we cut through it and see the crystal itself?
We did open up a failed crystal before, and the quartz disk
inside should look something like this, with two leads attached to it.
So let's try to give it a virtual cutty-cutty. And here we go in the package, and I see one
lead already. And there it is! We see the two leads and the disk of the crystal itself.
And here's the other lead. And I found that quite remarkable.
And just for fun, let’s cut it sideways, and
there it is, and you can see how thin the disk is. Here is the metal package envelope.
I think I can even spot the suspension wires that make contact on either side of the disk.
You can explore this to your heart’s content. Here we can see some of the PCB traces,
and even read the assembly number on the upper right.
A quick peek at the power supply at the bottom, simply because it’s pretty.
You can clearly see that the power supply is redundant, with two of everything.
Finally, a mystery for you to figure out. On the top of the box, just under the cover,
I see these two long cylinders held by clips. I have no idea what they could be. Maybe you can
figure it out. Go take a look for yourself, and put your best guesses in the comment section.
There you have it. The inside of the CTE box revealed.
We’ll probably dive into its inner functionality in another video,
but for now let’s admit it’s pretty complicated, or just plain pretty.
Alright, next up is my Apollo gyroscope, that we described in a previous episode.
This is one of the three gyroscopes that were the heart of the inertial platform,
the critical guidance sensor that measured the orientation of the spaceship.
Here, we admittedly are cheating a little bit, because we already
know from drawings what should be in it. But it is an entirely sealed assembly,
and there is no way to see the mechanism without destroying it. So, in the x-ray it goes.
[Jon] Duh, there it is!
[Marc] Oh! We see the wheel already! That is amazing.
[Ken] This box is like magic!
[Marc] It’s not magic, it’s downright witchcraft!
So here is our Apollo gyro, and we can cut through it like butter. We can see the gyro
wheel very easily, but it was harder to see the float in its beryllium sphere…
[From Galaxy Quest] The beryllium sphere of course!
[Marc] …probably because beryllium is so
transparent to x-ray compared to the steel that surrounds it.
But after a bit of meddling with the settings,
I could see the faint outline of the hermetic sphere that encloses the inertial wheel.
And if we keep chopping it from the end, we should get a good view of the magnetic suspension
and position resolver. Right here, you can see it quite well. And the inner ring here,
is the magnetic suspension, basically a magnetic levitation bearing. The outside ring is the
resolver, basically a very precise position sensor that will measure the movement of the gyro wheel.
So now I have expanded back, so we can see
the hermetic expansion bellows, to cope with the thermal expansion.
Now looking at the other end, the little bright spot is a ruby pivot,
and we see the same magnetic bearing on the inside, and this time a torque generator on
the outside and the bellows, so a very similar arrangement to the other side.
I took some pretty pictures, and here you can really see the faint outline of the beryllium
sphere. This is a beauty picture of the magnetic bearing and the torque generator.
Here you see the capacitors that are used to tune the magnetic suspension electronics,
and finally we could see the signal amplifier,
and it’s another cordwood module, which is potted and of course not visible without the x-ray.
That’s it, Apollo gyro in a nutshell.
You can imagine that the gyro platform needs quite a bit of power electronics around it
to make it work. These were located in the Power and Servo Assembly, or PSA.
And we just got one! Actually, this is engineering unit number one.
However, when we opened it up, a surprise was awaiting.
One of the power supplies had blown up. And of course, it’s entirely potted.
Is it repairable though? How extensive is the damage? We are about to find out.
[Jon] There we go, maybe we'll see what happened to it for the first time in 50 years!
[Marc] Yeah, it looks like they didn't even open the box, right?
[Mike] Yeah. [Marc] It was fully torqued, right?
[Ken] So, they just threw it away.
[Marc] They went: "oh, it went boom, let's take another one".
[Jon] Here it is. Uh, now I forgot how I oriented it when I put it in.
[Marc] Oh, it's a huge transformer! A huge toroidal
transformer in it. Oh, that's interesting.
Well, wouldn’t you know it, the patient looks much better on the x-ray than we thought.
It looks like a capacitor just blew its guts out. It’s this fellow here, and its guts are here. And
you can tell that on a normal capacitor, back on the other side, the caps have their guts inside.
Here is another good one. And there is no other sign of damage! We have the schematic for this
supply, and Mike already found that the blown capacitor is just a filter on the main 28V input.
His current theory is that it blew up, maybe from user error, like powering it backwards,
and just disconnected. And that the rest of the supply may be working just fine!
Which would explain why the PSA box was never repaired:
they never knew. So maybe it still works! To be verified in another episode…
And finally, we have another one of the undocumented Motorola modules that drove Ken
crazy, when he was reverse engineering the Apollo uplink data box. He figured out, after much work,
and correctly, that this one was a flip-flop. But now of course, we want to know what’s inside.
The mysterious Motorola module...
Oh, two transistors! It's a flip-flop with two transistors.
[Mike] And a lot of passsives!
[Marc] And of course, that one also came out spectacular.
Ken was all over it in no time, and completely reverse engineered it. He wrote a full article
on his blog. He identified every single component, drew the schematics,
explains how this J-K flip flop works in details. So, if you want to know all about this flip flop,
I’ll link Ken’s article in the doodly-doo as usual. And make sure you pay him a visit.
Not to steal his thunder, but just for kicks, some pretty views of the module.
It's just fantastic. This one of course is very thin,
and all potted in fairly transparent material to x-rays. You can even see the transistor
die in the package. That was the little square in the middle. Here is a zener diode.
Here is a regular diode. And here, I'm looking to show a resistor, which looks like a ghost
component, because the middle is not visible in the x-rays. So you only see the end caps.
And basically, this is just a wonderful toy. What a machine you've made, Lumafield, and
thanks a lot to help us out in our Apollo endeavors!
See you in the next episode!