PRECISVOX

Might as well start from the pix I have shown you before, together with one of a completely different and much more conventional-looking Precisvox I found on the internet; apologies to the source but I forgot to note the name.

Above is a series of pictures of the machine as I dismantled it. I must apologise for some of these pix; they are very much workshop pix and not as prettified as I usually give you. From these and the next set of pix you can see just how generally distressed and dirty the machine is. The paler paintwork in particular seems to attract a very stubborn layer of dirt that is most reluctant to shift. Note also the aluminium corrosion on the amp cover and the apparently very thin plating, which I assume to be nickel, which has worn away extensively. I was driven to the conclusion that a re-paint was the only option, as removing the dirt also tended to remove some of the paint which was, as you will have guessed by now, pretty thin to start with. Note in particular that pix 1 and 2 are AFTER a fair bit of cleaning. In pic 4, none of the labelled parts are parts of the infrastructure of the machine - they just sit on top, barely secured in place and adding nothing to the strength of the construction.

 As can be seen from this second batch of (mostly outdoor in this case) pix,the basic construction seems to be a bit like an old-fashioned car, with a chassis from which the rest of the bits depend, but with hints of monocoque construction in the reinforced wrap-round skin and the steel strips at each end which wrap round much of the base. These strips actually make the machine difficult to pick up, as you basically have to use the strips, which cut into your hands. There is a curious circular strip protruding at the front; this is part of a mechanism for raising and lowering the front of the machine.

I suspect part of the dirt derives from a feature that I have not yet quite bottomed. More or less in the centre of the assembly of stripped-down parts is a section with a long bent rod and a thin brass tube, attached to a sort of cylinder at the other end. My guess is that this is in fact a “press to oil” button, with the bent rod acting as a piston and the cylinder being an oil reservoir. You can see a tempting button at the end of the bent rod, which is just visible in the first pictures of the complete machine, sitting just in front of the lamphouse cap behind the top sprocket. My problem is that I cannot see how the oil gets into the reservoir in the first place – there is no way in other than the brass pipe or, just maybe, the plunger itself; however, I cannot remove the button to see if this is the answer and I am reluctant to use too much force. Anyway, my point is that over-eager use of this could help explain all that dirt. Together with the fact that the projector is probably pre-war, according to what I am told about the amp design, and any Belgian projector of that era could have had an adventurous life.

A fair bit of Bakelite is used in the construction. One of the side “wings” – dunno what else to call them – has broken at some point, and the ends of two of the decorative side strips are missing. There is also a break in one of the fitments for the lens housing, but generally the bakelite has survived well. The principal use is for the complex sprocket assembly, see pic 3 just above. The knob on top foxed me for a bit as it just turned uselessly, until I realised that pushing it down gave me an otherwise-absent inching knob. The sprocket retaining rollers are apparently fixed, ie no spring-loading or pivoting, altho’ these are present for the sound drum. There is also no way of dismantling the roller assemblies since, as with numerous other parts of the machine, they are made with rivets or similar and are not designed for easy cleaning. The cooling fan seems to be impossible to remove without damaging the machine by untwisting or bending numerous fold-over tags that are the method used to hold everything together. All the (now thinly-plated and worn) decorative strips on the amp cover are riveted in place, making any re-plating impossible and re-painting problematic. A triumph, perhaps, of style and cost-cutting over durability and practicality.

The outer cover is joined to the chassis partly by threaded inserts in the decorative bakelite strips along the side, plus sundry screws, but is cushioned by a strip of what looks like paper but is now totally saturated with oil. The arm assembly for the spool spindles is incredibly light, due to the use of incredibly thin-walled aluminium tube. But the spool spindle assemblies do at least come apart for cleaning.

The amplifier is a largely self-contained unit that is relatively easy to remove, but you do have to thread the photocell unit out. This is a separate little unit at the end of an “armoured” cable from the amp, and includes the PEC itself plus a valve and what is presumably a pre-amp circuit. Getting it out is a bit of a tight squeeze as the unit is quite substantial and has to pass thru the projector chassis. As I have mentioned, the valves and circuitry seem, according to my electronics advisor, to indicate a pre-war date. Construction of the amp is decidedly odd, because it actually sits over the top of the motor, surrounding it on 3 sides. The connections to the valve bases underneath the chassis are not direct; instead connections go to a disc about 1.5” away, incorporating various capacitors, resistors etc along the way, and connections to other parts of the amp are made from there. The amp unit also incorporates the control panel for the machine, including the lamp and motor switch. Labelling of this is done very much on the cheap, by means of a piece of thin, printed card with holes in to go over switches and sockets, and covered in turn by an equally flimsy sheet of transparent plastic. The original was rather the worse for wear, so I have photoshopped it. It refers to a tone control, which is not present on this machine. The “source” for the PEC is not an exciter lamp, but an inverted main projection lamp. This is the standard, pre-focus base type. I have never seen a lampholder as flimsy and inadequate as this one. It is constructed of very thin aluminium sheet and is almost impossible not to bend. It sits in a complex structure of thicker alu sheets, which is very difficult and fiddly to take apart, as taken apart it must be because of the filth that cakes it. Overall, apart from the amp, which is at least removable more or less in one piece, little is designed with maintenance and repair in mind.

I have marked on pic 4 in the second big set above the location of the mirror that directs light from the sound track to the PEC. The scrappy (curved) little mirror was held in place by Blu-tak when I got the machine; this alone will probably dictate a conversion to a modern cell, as there seems little or no support for the mirror and the correct positioning is going to be a bit of a trial and error game into which I do not wish to enter.

Probably the most difficult part to restore to a decent appearance is going to be the amplifier cover. This suffers from "alumiium rust", where some form of corrosion lifts the paint, produces white powder and leaves behind a pitted surface. It also has numerous teardrop shapes, whose nickel plating has worn thin and which are each fixed to the cover by two small rivets. These would be very difficult to remove without damage and equally difficlt to replace satisfactorily. Probably not worthwhile; needs more thought. Pic 6 in the second main set of pix above gives the clearest view of the lamphouse cover, which I cleaned off, again because of aluminium rust, with a paint stripping device running at high speed in a drill.