The Mystery Machine

[picture thereof]

I acquired this thing at a University of Texas surplus auction as part of a pallet full of scientific equipment. It was very heavy, bore no manufacturer's marque, and was evidently custom-built from scratch, for which sinister purpose I could not divine. The only external features were two 3-digit thumbwheel switches; two LCD displays; two BNC jacks; two fuse holders; two fan grills; one toggle switch; and three big buttons, labeled START, STOP, and RESET. Also: a length of electrical conduit containing two conductors sheathed in thick high-voltage rubber insulation, and a grounding bolt of heroic proportions, visible in this rear view.

The enclosure is constructed from 1/8" thick aluminum plate braced by 1/2" square aluminum bar stock, except for the face which is 1/4" plate. The complete unit weighs 80 lbs. without the external conduit, and measures 17½Hx16¾Wx12¼D.

Unbelievably, this battered monolith was not the most compelling piece of treasure from the UT haul, and so the forbidding technological ark languished untouched deep in my warehouse for six years and more. In fact, I had all but forgotten about it until a friend recently asked about a high-voltage power supply for ball-lightning experiments. Thinking back to my unidentified rack-mount object with the silicone-insulated cables, I finally resolved to take screwdriver in hand and lay bare its undoubtedly hazardous secrets. The next week, I took it apart.

Here's what I found inside. (Click the thumbnail links for larger images.)

[view from top] After removing 12 countersunk screws and lifting off the lid, a view from the top. The first thing you see is an imposing cylindrical aluminum pod, mounted in brackets milled from inch-thick nylon. Not much is visible besides the pod; you can see glimpses of a huge transformer thing on the left and a set of PCB cards on the right. It looked to me as if the secondary of the transformer was wired to the pod, and the brackets seem intended to provide insulation from the case. Without a better view I was loath to go poking my mortal flesh around in the box, and decided to remove the walls.

[view from right side] Off comes the right wall. In the foreground are three hand-wired Vector cards, plugged into a common bus. The middle card has pin headers for two cables on the left, the lowermost of which is unplugged. To the right of the card assembly is a 110VAC cooling fan. The transformer hazards a demure peek from its fastness beneath the aluminum pod, which is revealed to have a cooling fan in this end. The digital flash pictures posed no small source of excitement, presenting the best view inside the pod so far.

[view from left side] With the left wall removed, the plot thickens. As it becomes increasingly clear that the walls of the enclosure are critical structural components, the unit is placed on its heavy face for further study.

To the upper left, affixed to the back of the case, is a generic linear power supply, incorporating 7805/7815 and 7905/7915 regulators to supply +/-5VDC and +/-15VDC. Two silicone-insulated wires protrude from the big transformer thing through a carelessly-applied layer of insulating caulk, terminating in screw lugs which are evidently intended to connect to the pod. Now they lie loose in the case, along with four slim black fiber-optic cables. It appears that someone removed any connection to the pod before the device went on the auction block.

[all spread out] Removal of the bottom improves the view, but enlightenment remains elusive. The four fiber-optic cables connect to one of the Vector boards. The two BNC jacks at the front and back of the case are connected, evidently some kind of signal bus which tees off below the fiber in the card cage. [Detail shot of cards and connectors.] Various cables run between the card-edge connectors and the controls on the front of the box. Along with the two rubber cables two black wires emerge from the big transformer, one to a relay contact and one to a 120VAC common tie point.

Evidently the logic on the cards can control, via relay, power to the transformer, which probably generates some sort of horrifically high voltage to energize whatever is inside the pod. The fiber-optic cables convey signals to control and/or monitor the pod, while preserving its electrical isolation.

At least, that's how it appears. One thing is clear: for further answers we must travel inward, to expose the heart of darkness. We must open the pod.

To be continued.

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