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Seven thru-holes are drilled at locations chosen for having webbing in the plastic casting to support them. The filter basket was removed from the blower inlet. The blower inlet snout was sanded short, to allow unrestricted airflow beneath a mounting plate that will be suspended above it. A big drilled hole is provided for the wiring-harness to route through. The hole is sized for a four-pin Molex-Waldom box connector to pass through.
This Driver Deck baseplate was fabricated from 1/8" aluminum. Studs seen here pass through holes in the plastic housing shown above. Studs were sanded smooth at the middle, so they slide through the plastic holes without getting stuck. The big hole in the base-plate is for the blower's snout to stick through. All machined aluminum is treated with Chromate solution.
Shown above: this assembly holds the high voltage transformer, switch deck, and the snubbing resistors. Polycarbonate mounting plates isolate the snubber resistors from the chassis (chosen resistors are only rated for 1KV isolation with respect to chassis ground, and one of them sees 2760 volts peak). Holes direct airflow through the switch deck heatsink.
Shown above: Transformer, Snubber Resistors, and the Switch Deck are mounted. A 6 volt incandescent lamp is added to the 3 volt transformer output. 3 volt wires were fed through core holes before being attached to the bulb. Heatshrink tubing is added to the bulb. In the foreground, a tie point is provided for terminating chassis connections.
Shown above: Snubber Resistors are mounted to Polycarbonate mounting plates. Nylon locking hardware is used wherever possible, and especially where attachment to plastic becomes necessary.
Shown above: PVC Capacitor Holsters were fabricated to isolate capacitor cases from the Driver Deck chassis, and from each other. Pipe was selected for having an inner diameter matching capacitor-case outer diameter. Pop rivets attach all angle brackets. Note: rivet heads cannot touch the capacitor cases. Shown below: holes in the PVC are counterbored internally, so rivet heads can be recessed into the PVC.
Shown above: a trench is cut into each PVC pipe interior, to accommodate seams at capacitor case ends. Capacitor cases will be locked into these trenches by their seams, so they can't slide around.
Shown above: 25 mil Nomex is hot-glued over the rivet heads, so arcing will be unlikely between capacitor cases and rivet heads. Threaded angle brackets are riveted to one end of the cap bank. These will be used for mounting a bleeder board onto the end of the assembly. 8-32 Rivnuts are inserted for cap-bank mounting, and for use as electrical tie points.
Shown above: Capacitor Bank assembly begins with hose clamp installation. The bleeder board gets fitted next.
Bleeder Board
These resistors are made in Florida by Tepro. They are exceedingly cheap, but they come uncoated. Heat shrink tubing was added to protect the resistive elements. High voltage resistors have wires which tend to break off at the ends, if high vibration occurs in transit. Ideally all high voltage resistors should be anchored by Ty Wraps. To preserve Neon Bulbs leads, anchor wires are wrapped around the tips of each bulb, and these are fastened to the circuit board. Due to the presence of high voltage AC, all slip-lug connections shall be short and direct.
Shown above: black/white snubber capacitor wires are pulled taught enough that they won't touch the chassis. High voltage AC is present on these leads, which tends to break down insulation. High voltage tip: treat all high voltage AC and pulse lines as though they are bare conductors. (Run them telegraph-pole style.)
Shown above: the wire between the snubber resistors is also subjected to high voltage AC. Fiberglass cloth sleeving is slipped over the Teflon interconnect wire. This assures enough physical spacing from the chassis so breakdown of insulation will be unlikely.
Shown above: the capacitor bank is suspended a half an inch from the baseplate. This serves to isolate hose clamps and angle brackets from the chassis. High peak current conductors are doubled up: slip lugs are the weak link in this area. Normal high voltage practice is to tie all metallic objects to a known voltage. This prevents static ticking, which causes electrical noise. In our case, we are more concerned with insulation breakdown internal to the high voltage capacitors and snubber resistors. If capacitor cases or resistor mounting hardware were to eventually become energized here (perhaps due to internal dielectric failure) this shouldn't prove catastrophic. We aren't concerned with generating electrical noise. This shall only be used in case of emergency.
Pulse Driver Board input wiring routes with High Voltage Transformer primary wiring through a hole in the bulkhead (deliberately kept away from high voltage wiring).
Shown above: Applicator Coil wiring is attached.
Shown above: the Control Assembly is mounted. Not shown: the Driver Deck was bolted in place before the Control Assembly was mounted. Washers and Nylon Locking hardware were used to affix the Driver Deck. The Control Assembly stacks onto the 1/4-20 studs after Driver Deck is bolted in place.
Primary power control and low level logic is contained in the top compartment. The vacuum switch prevents application of high voltage without airflow.
Double-sided stick-tape attaches the capacitor to the rotary switch.
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