CT Scans Help Reverse Engineer Mystery Module

The degree to which computed tomography has been a boon to medical science is hard to overstate. CT scans give doctors a look inside the body that gives far more information about the spatial relationship of structures than a plain X-ray can. And as it turns out, CT scans are pretty handy for reverse engineering mystery electronic modules, too.

The fact that the mystery module in question is from Apollo-era test hardware leaves little room for surprise that [Ken Shirriff] is the person behind this fascinating little project. You’ll recall that [Ken] recently radiographically reverse engineered a pluggable module of unknown nature, using plain X-ray images taken at different angles to determine that the undocumented Motorola module was stuffed full of discrete components that formed part of a square wave to sine wave converter.

The module for this project, a flip-flop from Motorola and in the same form factor, went into an industrial CT scanner from an outfit called Lumafield, where X-rays were taken from multiple angles. The images were reassembled into a three-dimensional view by the scanner’s software, which gave a stunningly clear view of the components embedded within the module’s epoxy body. The cordwood construction method is obvious, and it’s pretty easy to tell what each component is. The transistors are obvious, as are the capacitors and diodes. The resistors were a little more subtle, though — careful examination revealed that some are carbon composition, while others are carbon film. It’s even possible to pick out which diodes are Zeners.

The CT scan data, along with some more traditional probing for component values, let [Ken] reverse engineer the whole circuit, which turned out to be a little different than a regular J-K flip-flop. Getting a non-destructive look inside feels a little like sitting alongside the engineers who originally built these things, which is pretty cool.

15 thoughts on “CT Scans Help Reverse Engineer Mystery Module

    1. Those machines are wicked expensive (plus required cal/maintenance) …so part of the cost they’re charging is to pay off the machine (and interest on the loan). In a country with national health care, that would be paid by your taxes.

      Now, those machines aren’t constantly in use (though that would be ideal and would lower your share of the costs). So, CAT scanning a mystery module could well be done as a part of some required calibration or functional testing activity, at no cost. There’s always a way to sneak a personal job in during downtime. I know of several instances where electronics or archaeological finds were X-rayed (not CAT scanned) using medical equipment.

      1. Indeed, these devices are not inexpensive to buy or maintain, however, this does not mean that several thousand $ scans are warranted. In Canada there are many private facilities that offer CT, MRI, etc and the cost of a CT scan itself including a review from a Radiologist range from $375 – $800 CAN ($290 – $620 USD). MRIs can range from $550 – $900 CAN ($495 – $700 USD). As indicated the cost of these scans are far cheaper than the cost posted by others.

        1. In Poland, a CT scan (including radiologist) costs somewhere between 50 and 150 USD and MRI is between 100 and 250 USD. But you only would pay that if you couldn’t get a referral from your doctor, or couldn’t wait for an appointment with a appropriate specialist (a family medicine doctor can’t order those scans).
          Wait times, once you have the referral, range (for my city) from one day to one year.

      2. Nice bit of info. Btw, CT scan in India costs ~$30 on average but can often be be as cheap as $12. It is easier to get much cheaper discounts if you book scan few days prior and/or book it during night. Also, it is always free for people with low income. I won’t refer to any specific hospital or laboratory but you can find one easily if you *oogle for CT scans in India.

      3. Our local vet has a cat scan – so I’ve actually seen a cat scan of a cat! – and it’s nowhere near capacity. Might be worth asking around vets; I’d imagine they’re more likely to be willing than human medical facilities. The scanner is designed for humans, with just a few plastic adaptors to hold animals still.

  1. Oh, and that mystery module was manufactured by Motorola, who seem to have no records of it. Was it a repurposed military, aircraft or land mobile part, or a complete custom for the space agency? Someone, somewhere knows the answer…

    1. NASA and Rocketdyne managed to lose the plans and manufacturing notes for the F-1 engine – the first stage of the Saturn V. So while we know how it worked and it’s general dimensions, we don’t know specifically how it was produced in terms of machining dimensions and specific assembly processes. Lost in time.

      That’s not even mentioning how NASA managed to “tape over” the magnetically stored telemetry and video downlink recordings from Apollo 11 in the 1980’s with LandSat telemetry.

  2. Lumafield is remarkable. Objectively, their specifications and image quality are mediocre compared to offerings from other players in that field, but they seem to have hit that trifecta sweet spot of “good enough” and “fast enough” and “cheap enough”.

    Plus their marketing is outstanding.

    I guess that’s what a few tens of millions of dollars of sillycon valley vulture capital money buys you.

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