Siemens

Siemens Silent

Here is a classic example for you of just how NOT to do it. A while ago, I acquired a (second) Siemens 16mm pre-war silent projector. They made several variations on the them, including both claw and beater (beta?) mechanisms and 9.5, 16 and dual models. My first was a beater 16, this second is a claw 16. The problem with the second machine was that when switched on, the lamp lit but there was no sign whatever of life from the motor. On examination, the mech proved to be pretty stiff, and oiling and running the machine with a drill/driver attached to a conveniently-accessible end of the motor shaft did not help. So I gradually took more and more bits off, trying to find where the stiffness originated. I think this was the first big mistake; attacking the job piecemeal with no clear idea of what I was going to do or how far I was going to dismantle. The second was relying far too much on memory. In the good old days, I could expect a fair degree of recall of how a projector was put together, even after a gap of several months. I did actually label most, but not all, of the wires I disconnected, but the problem is, I can no longer understand some of the things I wrote on the labels.

So, let this be a lesson to me and to you to work always in an organised way, with photo's, plans, sketches, diagrams and whatever (assuming you don't have a workshop manual), so that you don't face the task I had with this machine. I dismantled it ages ago; I've been putting off rebuilding it partly because I had found no solution, partly because it was very fiddly and partly because I knew I hadn't got good enough records of how to.

It was Paul Schimmel who put me on the right path. I had had to remove the motor, because there was no other way to uncouple it from the mech to see where the problem was, and it was the motor itself that was the problem. I had spotted that the brushes seemed to be at an odd angle to the commutator, but was then stuck. Paul spotted it was Mazac distortion. Loosened the screws holding the motor and lo! - the mech freed up. Some considerable time had already elapsed, and I continued to prevaricate until the other day. I finally got it back together and wired up as best I could in line with this wiring diagram. I have marked with a ? the connections I'm not really sure of.

However, perhaps my crowning folly was with the reversing switch. I didn't think it through, and just assumed that, in neutral, the motor would not run and, as shown in my wiring sketch, there should be no electrical contact made. What I subsequently came to realise was that the motor could not stop on neutral as the lamp would still be on and there was a mechanical linkage as well to the reversing lever that took care of that side of things. So I had needlessly bent the contacts, with no idea now of how they had been originally. I tried the projector, but I got no lamp even and still nothing from the motor. All I got was a red-hot glow from some thin windings at the lower end of the internal resistance, which may or may not have been there before. I wasn't too surprised the motor wouldn't work; even if I got the wiring right, it may well have been burnt out long before I got it. And the wires from the motor are single-core and therefore stiff; I may well have damaged them. Ron Ashton (Siemens Guru) tells me this Mazak business is a known problem with these machines and can readily cause them to be scrapped. Anyone need some spares?

Not, I think you will agree, my finest hour.

Here are some pix of my Siemens with the beater mech, showing how it changes size to effect the pull-down. I assume the extra roller at the top of the gate is needed because of the beater.

      

I have included pix of the claw machine to show that there are a surprising number of detailed changes and, of course, to show you some chitterlings. The beater has an inching knob on the back; the claw one is at the front immediately below the lens. Here's a publicity blurb.

 

Below is a 16mm Siemens. It has the beater-type mechanism, which naturally lends itself to dual 9.5/16 operation - no need for complicated claw arrangements. (For the benefit of newer nerds, a beater mech basically has a shaped pusher, which hits the lower loop and thereby pulls the film down in the gate. It never really caught on outside the toy arena, tho' the Siemens ones are reputed to work well - see the following review from Movie Maker).

   

 

More conventional machines with a claw were also produced, at least in single-gauge models. Right is a 9.5/16 beater, left an 8mm claw. Although it is missing in the opened-up machine, top right, the Siemens used an interchangeable resistance to match the power supply to the lamp voltage and wattage, a practice continued in their later sound projectors (16mm only).