KÖDERS 35mm projector

February 2022

I have been undertaking a task which I could not resist. I acquired, sight unseen, a 35mm “portable” (it feels like it weighs 0.5 tonnes or 'arf a ton as we used to say) projector, a Koders (acherly, it is in caps and hav an umlaut - Ö - but plain Koders is simpler for me). It rapidly transpired that what I would be undertaking was little less than rescuing a projector on the brink of oblivion. It has obviously been stored in the damp at some point, maybe even dripped on a little, and the result was pretty dire, as the main frame and body of the machine was aluminium alloy and so prone to the white “rust” that destroys any surface finish. The side cover and key components such as the sprockets and sound drum were steel. The former’s paint finish (some form of metallic hammered finish) was lifting and flaking across almost its entire surface, inside and out, with the extensive length of vents on each end panel suffering particularly from the rust which covered most of the entire side cover. The paint held on with any tenacity only in odd patches where paradoxically the rust underneath actually improved adhesion.


The sprockets, sound drum, pulleys etc are steel which has been chemically blackened. While offering some protection against rust, this is by no means perfect. There were multiple areas of “spotting”, where rust had pitted the steel. Fortunately, little of this was in key areas, but cosmetically it’s never going to be better than second rate. Not least because the front plate of the machine, a solid piece of alu alloy, is much affected by the white rust and, short of a complete dismantle and repaint and rebuild, it’s never going to amount to much. Possibly the worst of all the problems was the gate runners. These are two vertical strips of a Paxolin-type material, housed in slots and sprung to form the front part of the gate. Unfortunately, the slots are alu alloy and the runners were jammed solid, which took a bit of fixing.


 There is also a cover (with a pair of what I have to call very lightweight handles given what they do) that fixes to the baseboard of the projector via luggage-style catches. In my view, only the fact that the catches on the baseboard actually continued round the edge of the board with extra fixings underneath allowed those handles to pick up the projector at all. Although superficially it was not immediately obvious, the catches turned out to be pretty much destroyed by rust. Worse, this extended thru the fixings and on into the wood - the securing bolts were just little bars of rust with no apparent threads and I still ent got them all out. They have left the wood of the cover rather rotted. The wrap-round catches seem to be non-standard as I can't find them on the internet, and anyway the weakening of the wood is going to mean I shall need a pretty ingenious and non-standard solution.


You might by now be wondering why on earth I am bothering. The answer, basically, is that I love messing about with projectors and hate to see a machine like this so neglected. Partly I have always wondered why it seemed necessary for 35mm machines, even so-called portables like the GBN, to be so massive. Obviously, endurance and durability for commercial use, but even so. This machine is the closest I have seen to a 35mm machine that is more or less exactly like the sort of standard layout for a narrow-gauge machine – sprockets above and below and in front of the gate, sound drum below the lamphouse and only a few extra bits to allow for the intermittent sprocket, plus very conventional spool arms. This simplicity does not however do much to make this anything but a bit of a heavyweight.

                             

 These pix give you a sort of tour of the machine. In pic 1 I had already started dismantling. The bosses above and below the lens support the shafts for the sprockets. The spool arms fit over the black bosses top and bottom at the front. The two knobs at the rear are (top) the inching knob and (bottom) framing. The lump under the framing knob we will come to in a bit. The gate is open, the runners are still fixed solid. The cap for the sound drum is off, allowing us to see the unusual red PEC. It is at edges and corners that the damage to the paint finish is most visible, but none of it is terribly good.

Moving on, pic 2 starts to reveal the basic construction of the machine, with a thick upright plate carrying the mechanism, supported by a heavily-built framework carrying the motor and amp. This framework was painted all over like the front plate. To me, this seems pointless and little of it was any good, except for gradually spalling off and making a mess. I scraped most of it off with little difficulty. A monitor speaker seems pretty useless against the clatter of a 35mm machine, but nonetheless there is one; just to the right and below is a socket for an external speaker. Note the take-up belt is solid rubber (none of yer spring belts here!), given its grip purely by the weight of the arm and film. This leaves the slipping clutch at the end of the spool arm to provide all the necessary slippage, which on many narrow gauge machines is assisted or entirely dealt with by the spring belt.

In pic 3 can be seen the huge fibre gears for the sprockets, driven by what seems a tiny gear on the inching knob cum main drive shaft. The intermittent box, pretty much central in this pic, has its own flywheel and a drip tray below because it is directly above part of the amp(!?). This drip tray caused me untold trouble when I was re-fitting the sound drum because it was rubbing on the main flywheel. Having settled it in my own mind that the problem was to do with the way the positioning of the flywheel was adjusted (true, but not in the way I was thinking) it took me a while to realise what the problem actually was. The motor wouldn't work when I first powered it up, but when I got it turning fast enough by hand, it fired up, pointing the finger at the start capacitor, hanging loose here. A new one soon sorted it.

Moving on to pic 4, you can see the obvious crack in the base of the capacitor, which had leaked, so not surprising it wasn't working. This machine runs on 115 - 125 volts. The input is via a Bell and Howell plug. Now, I always have problems getting my head around these connectors because of that blasted duplication between two of the pins. This doesn't have that and I worry it might be a problem if some one just plugged an ordinary B&H connector in and iot didn't match the current wiring (I'm not sure it's original), so I shall probably repace it with a 3-pin receptacle of some kind.To the right of the input is the lump seen in pic 1. It is a multi-position switch which goes from (I think) power on to things like the amp and framing light, then motor on, lamp preheat then finally de woiks. This all seems a bit complicated to me, as I would prefer toggle switches like the one just right of the rotary control which is for the exciter lamp. However, this rotary thing seems to do the job so I'll prolly leave it. If you look closely, you can also just see where the sound flywheel and the verdammten drip tray intersect.

Pic 5 is a bird's eye view for completeness. Pix 6 and 7, however, show the underlying horrors of what damp and neglect have done. The plate at the top of pic 6 is the cover for the hole that gives access to the underside of the amp, which I have tucked into a remaining scrap of covering fabric just to show it for the record, so to speak. It seems a weird way to gain (partial) access, at the cost of having to tip up the very heavy machine. Incidentally, once the amp is out, it won't stand up straight because those caps on the tranny at the top of the amp protrude below everything else. There is little sign of rubber feet or similar protection, if there ever were any. You can however see the wraparound catches for the cover. 7 is a glorious Technicolor image of the amp, only closer up. Actually, the amp seems to be in pretty good condition. Except it doesn't work.

                    

 Just a few extra pix at this stage. The first two show there were limits to how far I was prepared to dismantle for a machine that would be utiltarian at best, tho' I did remove and clean some of the bits you see here. Note in particular the brass parts - brass don't much like paint and here had rejected it more or less completely - I just tidied up. Pic 3 is the worst example by some way of rust to the blackened steel parts. But it is the main drive pulley! 4 shows the mess rust made of the latches, catches and of the cover - I just don't think it would be safe to use the same holes without reinforcement, but note the wrapround on the catch part. 

I ent yet showed you the outer cover or the inner mech side cover.

                    

The outside looked quite respectable at first, until you looked at the latches. Note the cut-out of the base front left, which the cover extends into. This makes room for the take-up reel. The inside was difficult to photgraph as it's all terribly red and my poor little camera didn't know where to focus. There was a lot of discolourisation and white mould-like powder, quite apart from the internal "anchor" pieces for the handles, which have almost completely rotted away. And the felt lining had come loose and was ready to go further.
Pic 3 shows the inside of the mech side cover. This shot is after a lot of work removing not so much the flaking paint as the more stubborn bits that had managed to stay stuck on and sanding away the worst of the rust. The area along the top of the rear of the cover (about two thirds of the way up this pic) was heavily covered by thick layers of paint both inside and out, under which was a lot of filler with, underneath that, the rust you see here. I am a believer in getting to the root of rust rather than covering it with another coat of paint, so did more work and applied rust killer. Ironic that it was the rust creating the adhesion of the paint in this area. It appears to be some sort of butt-weld; I have no idea why as such a curve would seem no problem at all for steel of this fairly thin section. Maybe the sides and top are a single piece, with the specialised pressing for the vents all on the one piece? Pic 4 shows the vents which are as usual very difficult to work on - I had quite a bit more to do after this pic was taken. Pic 5 is a detail of that join seen in pic 3.

                              

I suppose you could call this batch of pix "after" pix, although I have done little with the paint on the main plate of the mechanism.I have however had a go at painting the side cover with silver grey Hammerite. Far from perfect - it's just too big for my small workspace - but at least it will look better, runs notwithstanding, than it did when I started and won't rust for a while. I now need to clean up the top cover, re-cover the base and devise a solution to the fixings and appearance issues. Then there is the amp, tho I may cheat and just use a diode fed to an external amp, tho the exciter lamp feed seems to come from the amp tranny. So, plenty more to do yet, but now it runs and has light. It also has that typical 35mm clatter - no wonder they usually got shut up in a boof. 

I have explained my problem about the catches that both held the lid on and supported the entire, very considerable, weight of the projector. I cannot find any catches which do the job in a way I consider safe, particularly repeating the wrap-round under the base from the original. I needed to put the new arrangement in the same place as the old catches because the mess left under them is so extensive I wanted something to both cover it and add strength. I have therefore come up with my own, multi-part solution.
First, a piece of aluminium angle about 70mm wide and with the angled sides about 0.5” (edge of baseboard) and 1.5” (underneath baseboard) is screwed to the baseboard from underneath. The short edge is screwed to the side of the baseboard, but with screws first passing through one half of a substantial hinge that (and this is the key to the entire approach) has a removable pin.
The other half of the hinge is fixed to the cover, with bolts passing thru first the hinge, then an aluminium plate about 70mm square, then the cover itself, then another aluminium plate (70mm square again) and finally secured by washers and nuts. Two further bolts in the upper portion of the aluminium plates complete the fixings.
All of this is of course much simpler to see with a couple of photos; here they are.

The first pic is from underneath the baseboard, showing the wrap-round I consider essential - can't expect a few screws into the thin edge of a piece of plywood to do the job on their own. I managed finally to get a decent shot of the inside of the cover. I shall need to do some trimming of the bolts to prevent scratching the machine (even more).

I can’t claim the result is as good as the original, as the lower part of the hinge protrudes above the edge of the baseboard but, even if I could find direct replacements, I don’t think they would work without the strengthening I have incorporated. In fact, I am beginning to wonder if I might have been better off making an entirely new base.

Then there is the question of feet. The bottom of the baseboard appears to have been covered with the same material as the sides and top, but with use and damp it was loose and useless, what there was left. I can’t really tell if there were ever feet but, if there were, they are long gone. Leaving a flat surface that would inevitably be abraded (and abrasive) seemed ineligible so, after much pondering, I fitted 6 Teflon gliders, supporting the baseboard at the three main corners and at the three “corners” of the cut-out. Once I had the machine set up, it became apparent just how badly the baseboard had been weakened, as it sagged almost to the platform it was on between the two rear feet. I shall probably have to reinforce.

Some Time Later.......

I have been struggling to commission this verdammten machine, but it has continued to place obstacles in my way. Let me deal first with the amplifier. I got it working with an external input to the mike socket, and it gives a really good, clear result. So far so good. I installed a diode in place of the PEC, and the problems started. There was insufficient volume, tho’ I could tell something was there. So I dug out a pre-amp, made many years ago. Since then, I have had nothing but spits, crackles, tearing noises – the usual gamut – and, before you point out the obvious, this has now retroactively affected the external input – without the pre-amp. I also get complete loss of sound, very patchily, involving much fiddling with the jack input to try to get it right – and failing for any serious length of time. More work required here, obviously.

Another thing that happened was when I re-wired the lamp (I’ll explain why in a bit). My increasing clumsiness helped me to break the lampholder and socket, tho’ spares were of course lying around in my lampholders box and the lamp attic.

Even more aggravating has been the behaviour of the film transport mech. This has basically involved two problems. The first is longitudinal splits in the film, anything from just the sprockets to halfway across the frame – and 35mm don’t ‘arf get thru a lot of film in the time it takes to notice, panic, then act. Fortunately, I am only using an aged batch of trailers, but all that splicing and re-threading takes up time. As does finding the 35mm rewind arms, which I didn’t think I would ever need and had put away somewhere, and their baseboard, making extra holes and re-positioning the arms (don’t ask), so that I can start again without scarring a new piece of film. And dismantling and sorting the splicer, which was obviously in dire need of both blade and punch being sharpened. I think one of the defining features of using old cine equipment is the constant need for maintenance and repair and the requirement for a large range of equipment and tools and spares to help. And if you ent used it for a while, few projectors will forgive you easily.

But I digress. The second problem is the film just snapping, initially because the take-up needs help to start, and snatches when it catches up. This is not too difficult to deal with, but becomes much tougher when it keeps happening because the main projector control is rotary and every step in the sequence involves a break in power supply, eg after “motor on” there is a disconnect before “motor plus lamp pre-heat” and another between that and “lamp full on”. These stops re-prime, so to speak, the need for help to the take-up. Now we have all started narrow gauge films with slack in the take-up and just let it catch up, but 35mm does not like this because everything moves too damned fast, and the film breaks. Most recently, the film broke when I stopped the machine with film still running. I have adjusted both the take-up and the feed tension to help deal with this.

Now, I have often suspected that the rotary control on the machine when I got it was not original, and the realisation of the breaks in the power supply tended to reinforce this view. So I decided to re-wire with switches, which is more what I am used to. After much lucubration (I have no idea where I got this word from but I think it just means thought), I came up with:-

a) a double-throw motor switch with centre off, up being motor only and down power to both motor and lamp switch. This is to enable the motor to be run eg for cooling without the pre-heat on.

b) a double-throw lamp switch with only two positions, up being pre-heat and down full power; the lamp pre-heat therefore comes on when the motor starts. I am assuming it don’t need long in pre-heat.

c) separate switching for the amp and the exciter. In effect, the amp switch allows power to the valve heating circuits, the separate on-off switch on the amp volume controlling the rest of the amp. The exciter has its own switch although the supply is actually from the amp – I am not actually sure where in this chain of switches the exciter falls. A pilot lamp circuit relies on its own switch direct from the power inlet.

All this required quite a bit of re-wiring, in the course of which I busted the lampholder and the pins of the lamp itself, which seem to be more sensitive to being “adjusted” (bent), said adjusting forces resulting from a failed attempt to repair part of the lampholder with superglue, which rarely seems to work for me. Another part of the re-wiring was to swap the inputs. As received, all the switching was on the negative side and I felt uncomfortable with this.

The machine arrived with the old-style 4-pin-plus-location-pin B&H 110v plug and socket, but wired for 3 wire input. I always felt dubious about this – what if someone plugged a differently-wired plug in? Might one get a live chassis? So I swapped it for a C19 and C20 IEC pair – these look like a slightly larger version of the usual C13/C14 pair of the standard kettle lead, but with the pins horizontal rather than vertical. No-one is likely to stick the wrong lead into that, as they seem difficult to find. You can see the new electrical set-up below.