Vox 2
PATHÉ VOX & SUPER VOX Page 2
I have various Vox and Super Vox machines, some more or less complete, others just for spares, and I recently turned my attention to one of these. It has been awaiting attention, as mazac distortion of the motor end cap was causing the motor to labour and grind.
As you can see, there has already been one repair, to the lower locating lugs, but there was also a crack across the top of the motor, clearly the source of the problem. The piece affected fell out when I opened up the motor. However, several years ago I had a Super Vox motor rewound, and had fitted it with the new aluminium end cap I had previously made. The obvious thing was to try this in place of the busted motor. First, I found that I had not actually got the gear bracket quite correctly placed - there was no room to get the worm on - so I had to do some stretching of the bearing holes where the shaft carrying the horizontal gear rides. These are separate items, held in place by a nut, so there is scope to deal with enlarged holes and still get a good fit.
Alas, the motor would not turn the mech. Fine in neutral, but with a load, even manual assist was no help. Until I cranked the voltage up to 180 or more, that is, but then I got a bit of smoke so backed off hurriedly. I don't know enough to figure this, so I have sent the motor back to the rewinders to find out what gives. If by some chance it was erroneously rewound for 240v, this would be fine as the projector itself has been wired for 230v. Which is another oddity - the motor is fed with 230v and uses a 4uF capacitor. Now I am used to 110v and 10uF and I do not understand this. Has this motor been wound for 230v? If there is anyone out there who knows this machine and/or worked on it in the past, any guidance would be gratefully received.
The amp has been re-built using two EL84, an ECC83, an EF86 and an ols metal valve. At the time it was done, this would have been close to state-of-the-art.
The sound on this machine was low when I first tested it, so I thought I would go thru and replace all the capacitors, as usual. This improved the sound no end - first I got a loud hum, which did not vary with the amp controls, then I managed to improve things by getting the hum to vary with one of the controls. As you know, I am no good with electronics so this is waiting 'til I can find a repairer. I did learn something new, however. I had not previously come across - colour-coded capacitors; this has 2.
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I've also been working on a Super Vox where the mech was stiff for no apparent reason. This is an unusual machine in that it retains the original amp, modified only by the addition of a volume control, and the original lamp. I'd quite like to have one in original condition. I also realised that, despite the Vox being one of my all-time favrites, I have not showed you pix of its innards.
This machine has obviously had some fairly crude over-painting done at some time, but it seems also to have had a defective paint job on the main mech casting. The paint finish on a Vox is particularly tough to keep clean; it always seems to be absorbing oil and feeling grimy. In cleaning up and de-greasing, it became apparent that the paint on the mech casting was all just going to flake off, so I removed the lot (externally, at least). Hence these rather naked-looking pix.
You can see from the last 2 pix that the disintegrating paint extends to the inside, which is why I believe it must have been an original fault rather than the result of later intervention. The question now is just what to do about the paint finish.
In pic 1, I have removed everything except the front part of the lamphouse, which carries the rear, sprung gate, and the two sprockets. The lower because I am reluctant to meddle; the big lower gear is secured by a pin. These are, in my experience, hard to remove and would risk bending the main shaft further than it probably already is. I think this is a major weakness of the design - there is too much shaft and no end bearing beyond the motor drive gears to help take the load. The upper sprocket is still there because I have never yet succeeded in removing one from any Vox or Super Vox - I have found that nut impossible to shift.
Pix 3 and 4 still do not really show the full story - I shall have to dig out a mech I can strip down a bit more. Anyway, working from the big gear at the bottom; this is on the main drive shaft which is turned by the motor. Above it is a beefy gear which is on the camshaft for the claw. Size and weight means that it must have a degree of flywheel function. This is not directly driven by the lower big gear but via an ntermediary gear which can just be seen peeking out from below it (see pix below). This intermediary engages with a very small diameter gear which is an integral part of the rear of the cam/flywheel gear. The next stage of the drive is also obscured here - I really will have to do more pix, but obviously connects to the horizontal shutter shaft and on to the worm drive to the top sprocket. Presumably, the purpose of these gear trains is to speed up the camshaft to 8 times the speed of the main drive shaft (which carries the lower, 8-tooth sprocket, and then to slow it down again by the same factor to drive the top sprocket. Interestingly, the original 200w Vox had a chain drive between the sprockets, which seems a much easier solution. So presumably it was found to present problems? Here are some pix, including a stitch-up of the two mechs together.
It doesn't look to me Pathé had to make any significant change to the main mech casting when they changed the gearing.
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The Super Vox I had been working on was the first real test of my home-made motor end cap. I have had continuing problems with the mech being ridiculously stiff, and have spent a fair bit of time chasing down the cause. The side of the mech, right next to the motor, is a steel plate with brass bushes in which 3 of the main mech shafts are journalled. You can 
see two here; the third is the main drive shaft at the bottom. As soon as I put this side back on, having freed up the mech (I thought), it would seize up again.
I eventually found that the top shaft, carrying the top sprocket, was out of alignment and binding. A small enough thing, but a very big effect.
It was ok if the sprocket was not locked onto the shaft by the external nut on the opposite side - this tightened everything up. Without it, the shaft could find its own position more readily. I therefore had to drill and tap the sprocket for a grub screw as an alternate means of holding it on to the shaft.
An oddity with this machine became apparent when I cleaned the usual huge accumulation of dried grease from the claw and cam. Normally, the Vox cam is secured to the shaft by a left-hand thread screw. This was is more or less riveted on - ie it cannot be removed. This is part of the reason for the fact that the claw was flopping about all over the place. There was considerable in and out movement of the shaft, and nothing could be done without dismantling the mech. I had to remove the upper large gear seen here and adjust its position to remove the in and out problem. As for the amp, my friend Paul took pity on me and took it away to fix.
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Here are some more pix, of a second Super Vox mech, on which I have loosened the camshaft gear. In pic one you see the sort of state some machines are allowed to get into (you should have seen the claw when I removed it from here). You don't want to see the appalling gunge I excavated from beneath the cam/flywheel gear and the big lower gear (I decided to remove this as well while I was at it), but if you DID see it, you would not want it in your projector. Pic 2 is because I had already removed the shutter on the first mech before taking the pictures above).
When I first cleaned this second mech up to photograph for you, the drive between the big lower gear and the next, intermediate gear, was rough - it semi-jammed several times on each rotation. Now, as you may have noticed, Pathé France never used a straight-cut gear where a helical gear would do, witness the drive to the shutter in the PathBaby. It is much more difficult to clean these - not least because old grease and oil, dried out and combined with the grit, dust, moisture and general groo that accumulates over time can form surprisingly hard and tenacious deposits. These are, of course, even harder to remove from slidey, helicoidal gears than from straight ones. Even a toothbrush won't hack it and I am often driven to clear it out groove by groove with a screwdriver tip. When I had done this to the cam/flywheel gear and the intermediary, everything was immediately much smoother. I wonder in retrospect if this contributed to the problem of stiffness on the first mech. What I am not clear about is why such complex and hard-to-make gears were so extensively used. Compactness may be part of it, and it may actually not be feasible to do right-angle turns without it. But even between the big lower gear and the intermediate gear, the drive has a modest helical component. Perhaps it is noise, or wear? Is there an engineer in the house? Anyway, back to the first Super Vox mech.
The problem was that, after I had cleaned up and lubricated, I could find no cause for the first mech to be stiff. I think, however, that I spotted something when I re-attached the side plate. There is a clue in the locating pin, just visible in profile below the motor shaft in pic 2 and also in pic 3 of the first set of pix. You may also just be able to see a second on the support pillar immediately above the cam/flywheel gear - it is somewhat clearer in the second set of pix. My experience is that such pins are only used when great accuracy of fitting is required, and I did indeed find that the precise positioning of the side plate had a considerable effect on the degree of stiffness of the mech. I suspect that bearing wear - the two sprocket shafts and the cam/flywheel gear all have bearings which are a part of the side plate - and imprecision of fixing screw location combine to allow the mech to "bind" and so become stiff. By trial-and-error shifting of the side , I was able to get a free-running mech.
However, this was far from all. The first "service" on a projector that has not been touched for many years inevitably reveals all sorts of problems, quite apart from the paint job. Removing the amp revealed that the insulation on the wires feeding the amp (carrying 110v) had gone brittle and disintegrated. Also, at some stage the motor switch must have failed and been replaced by a very non-original toggle switch. I had one spare, but it meant more re-wiring. The motor capacitor had split open and had to be replaced. The lamp wires literally cracked when I removed the lamphouse and so caused them to bend, so they too had to go.
I had also found that some of the contacts on the main terminal strip in the base were defective. These are brass strips with two screw connectors, let into the bakelite of the body of the terminal strip, so as to be flush with the surface. Two of these strips had popped out of their slots and were vaguely floating above and did not want to go back in. I imagine the very solid, thick brass wires of the lamp feed from the tranny were the cause of this problem. It is impossible to do much with Vox wiring without loosening this terminal strip and bending it back against the resistance of all the solid-core wires. I assume the problem (which I also have on another machine) had arisen when bending the terminal strip back into place, with the lamp wires being especially reluctant. However, I found a solution in the shape of a toolmaker's clamp, which grips with two flat surfaces. By gently and progressively tightening the clamp, the brass strips were persuaded back into place.
Having replaced various wires as described, I allowed myself to believe that the motor wires were OK. This motor had four wires, in two pairs of the braided cotton-covered wire so often used at one time. Each pair was twisted together. Now, the problem with the Super Vox motor wires is that they have to go down a hole immediately below the motor, then find their way past the back of the tranny - their route is not visible from above or below. Then they have to be pulled thru the tangle of wires connecting to the terminal strip to get to their own connections. This with a motor where the wires date from over 70 years ago. As it happened, the motor worked fine when I fired it up. There was just this wee problem of the 110v reading on my multi-meter between the body of the projector and earth, identified by sparking of the earth connection and tripping of the power supply. When I removed the motor once more and examined the wires at the point where they enter the machine, the insulation had clearly deteriorated. This is a bit tricky, as it is only an inch or less from where the wires disappear inside the motor casing, and the insulation is not exactly in prime condition - it is perfectly possible that the perishing of the insulation could extend into the motor and, if the wires are disturbed too much, would be impossible to repair without a complete re-wind. I stripped and cleaned up wires - without treatment, these old wires will not take solder - soldered on new wires and added plenty of heat-shrink sleeving to tie the new wires to the old and provide additional mechanical support to the joins. Fortunately this worked, but I fear this issue will be an increasing source of problems for the future.
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I have also been contending with a Super Vox with a type of fault I had not encountered before, at least, not in the location it turned out to be in. Basically, the drive train from the motor to the various parts of the mech was breaking down intermittently and "missing", rather like cars in the bad old good old days and in particular leaving the bottom sprocket running normally while the rest hesitated from time to time. The results were not good. It rapidly became apparent that the fault lay inside the mech casing. This means taking the side off, which means taking the motor off which means unthreading the motor wires from its connections in the base. In this case, the machine had been well "got at", with a modern solid state amp in the base and a big tranny in the old amp case for a 24v tungsten halogen lamp. Seems a little perverse, but the tranny apparently to hand at the time was too big to go in the base> Why not then you ask, simply remove a few turns from the secondary winding of the original tranny to get down to 24v. One of lif'e's little mysteries. The whole thing has probably left the machine heavier if anything. To get at the motor wires, the amp, the connecting strip and the (replacement) power inlet all had to be removed.
Anway, to cut a long story short, I traced the problem to the interface between a fibre gear and a brass gear, one of them having its threads heavily worn away. Contrary to all my expectations, it was the brass gear that had worn and the fibre gear, though somewhat affected, appeared still functional. For a long time I believed fibre gears were for quieter running; later I was told they were there to be a weak link in the chain, one that would fail before anything else did. Perhaps that applies only to catastrophic failure rather than wear over time. Let me start with this pic. Incidentally, I think the gold-coloured sheen you can see in places on the mech casing may be very finely-divided brass.
This is a view from the rear of the machine,ie opposite to the direction of projection, and from the back, ie the side opposite the sprockets, switches etc, and with the machine lying on its front side. From the left, we have a large brass gear; this is mounted directly on the main shaft, which carries the motor speed change gears at one end and the lower sprocket at the other. Next we have a small fibre gear (this one is the replacement I have fitted), partly hidden by another brass gear. What you cannot see is that the fibre gear engages with the lower end of the brass gear, which is about 0.5" in diameter, so we have two stages that increase the speed in the drive. There was sufficient play in the system to allow the fibre gear to lose contact with the large brass gear on the left, so intermittently failing to drive all the rest of the mech apart from the bottom sprocket. Also unseen is the fact that the fibre gear's shaft, on this machine at least, passes through into the claw chamber where the end of the shaft serves as an anchor for the spring attached to the bottom of the claw itself. The shaft of the right-hand brass gear carries at its other end a circular disc to which the claw cam is attached. The bearings for these shafts are faily thin, in the main mechanism casting.
Just to complete the drive train, here is an overview. The gear on the outer rim of the second brass wheel engages with another fibre gear - another significant step-up in speed - on which is mounted the shutter (out of pic to the right). Then we have a small speed reduction onwards to a major speed reduction via the final worm drive to the gear on the top sprocket. These final two stages are shown in close-up in pic 2 above.No doubt you are well ahead of me here in noting a major speed rise up to the shutter, all of it then shed to bring the top sprocket speed in line with the lower. In the Vox, this is avoided by the use of a direct chain drive from top to bottom. Much more on all this above. I don't know why they changed from chain to gears, but it explains one thing; the metal plate forming the side of the mech is identical in Vox and Super Vox, apart from a small displacement of the bearing for the top sprocket shaft, necessitated by the size of the gear needed to bring the speed down for the top sprocket.
Now we get to the meat of the matter. I had to remove the hefty brass gear (some flywheel/stabilising purpose?). This was secured in place by one of those abominable transverse pins, which go thru a hole, tapered all the way, thru first one side of the gear, then the shaft, then the other side of the gear. The original gear also has a grub screw for good measure. Over time, these pins seem to seize in place and can be the devil to remove; this was not the first time I have had to resort to drilling to help the pin out. I found a box with all the gear train components of another Super Vox to enable me to replace the hefty brass gear and the fibre gear. Here's why.
The two gears in pic 1 are the originals; you can just about see some scoring round the rim of the fibre gear but the real damage was to the brass gear, best seen in pic 2. It is hard to say whether the chicken of looseness in the way these two gears were mounted came before the egg of damage to the gears or vice versa or, indeed, a bit of both. But it meant I definitely had to replace the brass gear and felt it sensible to replace the fibre one, too. Here more anomalies came to light. The pin in pic 1 was from the replacement fibre gear, and has a diameter to match the hole thru the gear. Hiowever, it is much too short to do the same job as the one on this machine. Instead, the fibre gear fits over a spigot on the body, then this is held in place by a thru rod - in this case with a screw thread along its entire length. It is then secured inside the claw chamber with a couple of nuts, leaving a short length for the claw spring to attach. The screwed rod was smaller in diameter than the hole thru which it passed. Now, this should not in principle affect the centricity of the gear, as it rotates around the spigot on the body, not the rod, but it still didn't seem right to me, so I replaced it with an M3 machine screw. It was then a matter of careful selection of washers to ensure the gear is held tightly in place but still free to rotate.
The rod in pic 3 above serves as the shaft for the brass gear; this one however lacks the circular disc which is force- or heat- fixed onto the end. The claw cam then fits onto this disc. If the disc comes off, as here, I'm not sure if it can reliably be re-attached. Not a problem here anyway. The replacement brass gear still seems to have provision for one of those transverse pins, but it also has two grub screws, plus a flat filed onto the rod to give one of the screws a much firmer fit. I am hoping this will work without a pin.
That's about it, except for the part I don't like, which is putting the whole thing back together to see if it actually works. I shall have to completely re-assemble the machine as there is no half-way stage at which I could stop and test before moving on - it's all or nothing. And of course it was all too stiff - rather like the problem outlined above - so I have to go back to square one, especially if I have to go back to the original fibre gear; the problem appears so far to be with the shaft of the new brass gear (which must be changed) binding in the bearing in the side plate - it turns OK until I put that back on.
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December 2021
Bin having another of those marathon struggles with a recalcitrant projector. This goes back to when I had to fix a Super Vox problem with some stripped teeth in an odd location, on the same machine - see above. It now turns out that the shutter timing was wrong (tho' it's hard to tell when there is so much slack in the system). This means as a minimum taking off the lamphouse. The original gasket, already in two pieces, got worse in the process, so I decided to make a new one. I made a mistake with the first version, by using a sort of rubberised cork material, which tends to stretch and go floopy. A first attempt at re-timing the shutter having failed, the lamphouse had to come off again and the gasket did not survive, so I've had to make another. First time, I tried to copy the old gasket, but this was actually quite tricky and inaccurate, so this time I used a spare gate plate casting, to which the lamphouse attaches with the gasket between. I clamped this over the gasket stuff and cut round with a freshly sharpened Stanley knife. One word of warning about this. There are four screws that directly join the lamphouse and gate casting, three entering from the front of the gate plate and one from the rear, accessed by a hole thru the fanhouse casting. It is easy (I speak from experience.......) to confuse the small threaded hole that this back screw goes into with another adjacent hole which looks just like the ones from the front. Not disastrous, as the false hole falls outside the gasket area and there is still room for making the hole in the correct place.
This simple account conceals a horror of failed compoments, dropped screws and hours (and hours) of time. Amongst other things, the lamp holder failed - it had one of those slotted things with two channels that take the pins of the lamp as you insert it. I don't rate them; this one had burnt out. I cut away unecessary bits and just used the lampholder part, with a socket with flying leads that just plugs onto the lamp. Then the motor switch failed.
We now enter territory safe only for the deepest-dyed nerds (like me) as others will be cut down by terminal boredom. Here are some pix for you.
I have made up some names for various bits so as to label them in pic 1. Note incidentally that there is also a lamp switch which is virtually identical, but has the contacts, with terminals, on both sides - see switch base. (This enables the pilot light to be on when at rest but cut out when the lamp is turned on). The lever frame attaches to the base thru the two larger holes on the frame, into the marked holes.One problem is that rivets are used for this, so it cannot be taken apart without drilling out the peened over bit either on top or below, leaving the question of how to re-fix. The other two holes in the lever frame are threaded and accept the screws from the outside of the main projector base casting to secure the switch to the body of the machine. Pic 2 shows the other side of the lever frame and one of the rivets.
There is a groove in the RH end of the lever as shown in pic 1, into which the lever pivot fits loosely, and then the slot for the lever pivot rides on the central section. The spring fits between the lever pivot and the washer and is compressed quite a bit when fully assembled. The contact pivot point should ride in the centre section of what should be one contact, not two. The failure was in the breakage of the central section of the contact, seen more clearly in the inset at bottom right. Pic 3 shows how I planned to re-fix the switch. I cautiously countersunk the two former rivet holes to take M3 screws and leave a flat surface - said surface is right up against the inside of the projector base casting and if not flat would leave the switch moveable or eneven. The trusty box of spare spacing bits yielded up the "nuts" seen here (I think they were once part of spacers for a film spool). I have also cut a slot for a screwdriver in one end, after taking this pic, as spanner access is non-existent.
The problem is I have been quite unable to manipulate the various parts (including a replacement contact thingy I made on the lathe) so as to get them together against the force of the spring. This is part incompetence, part arthritis and part my long-standing neuropathy (which is taking away all the feeling in my fingertips). I shall have to find a young person who does not suffer from any of these three problems. So in the end I just cannibalised, from a machine already much altered and which if it ever sees the light of film again will not suffer from having non-original switched. And I still don't know if the shutter is right and now the amp seems to be playing up and, as you know, I am not an electronics sort of person.
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I acquired an unusual item at a Harpenden Fair, a junk Vox for spares. It does however have one or two unusual features that I thought might interest you. Here are some pix.
I like the neat idea of a sliding lampholder (pix 1 and 2), which may well be adaptable in the future, tho’ as you can see someone has dropped this poor machine on its head, causing cracks and no doubt completely wrecking the Bakelite parts of the lamphouse top. The mirror that reflected the light from the sound track to the PEC has been eliminated entirely, as well as the bracket it sat on. Instead, we have a two-part holder for a diode (pix 3-5). One part screws into the hole in the centre of the flywheel, with a small hole in the right place thru which the light passes to a diode in the second part. This relies on a complete re-vamping of the flywheel arrangement (seen from the back in pic 6) and, although it deals with any problem there might be of stray light getting to the diode, it seems a huge amount of work for a dubious gain. Fitting the diode directly in place of the mirror works very well and is a lot easier. Note also that the sound reader assembly and telescope appear completely new. I like the shield against stray light getting to the diode from the bottom of the lamphouse; normally this is inside, but having both might be a good idea. Given this shielding, it is hard to see why the re-vamp of the sound reading set-up was needed at all.
Some other work has been done, too. In pic 6, you can see that a roller race has been fitted in place of the simple brass bearing on the end of the claw shaft. There may be something behind the little cover seen just above it; not had time to investigate yet.
After all the careful work I have just described, it seems even more unfathomable that, for some bizarre reason, someone has considered that green hammered paint, applied thinly, badly and inconsistently, was somehow a good look! Still, I have a motor, various other useful spares and a couple of interesting ideas I can maybe build on.
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Ian Green found this on ebay. The poster confirms it really did exist. And I have a 16mm Super Vox sprung gate casting as further evidence.
Has anyone ever actually seen one of these? Did it ever go into production? It's obviously very similar in appearance to the Pathé Vox, but why would they want to copy that?
These pix are close-ups of the sound unit on a Vox ( a Super in this case, tho' I don't think there was any difference) which I took for Aunt Em to use in response to an email enquiry. See Aunt Em - Vox.
The round thing is the light spill preventer, which sits on the base of the lamphouse on the top of the sound telescope.
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