Premier Pathescope Repairs (2) October 2011

Now working on my third Pathescope Premier 28mm projector, the second that is not mine. This one has a different lamphouse, and came with grotty replacement arms and no shutter. Here are some pix.

 

                         

 

                         

  

I've shown the lamphouse with the back partly withdrawn. It's a little bit like a KOK lamphouse, with those runners riding on the inside of the front part of the lamphouse, but here the runners protrude well beyond the rim of the rear part. As you can imagine, when pushed fully home, the lamphouse is fairly shallow. The bulb it came with is a nondescript thing about 3" high and less than 1" diameter, with no markings whatever. This one has the original resistance; one hopes that originally the control lever was covered with some plastic fitment. The electrical connections I have yet to sort out. The resistance has just a 2-pin plug (R in pic 4), with no sign of provision for any other lead to enter the resistance cage; this suggests it is in line with one side of the lamp power supply, with the other side connected direct to the mains (only 110v, thankfully). The centre 2-pin plug is presumably the mains plug; this passes to the rather posh switch and then on to the base of the machine at the side. Another lead, L in the pic, comes from the back of the projector and on first examination appears to have four pin sockets. Haven't gone inside yet to see what is going on.

Having been putting off the job for some time, I had a brainwave about the spool arms. The two shown here are Debrie D16 top arms; the rounded base of the arm is little different from the original arms on my own Premier. I had to make the big securing nuts (not too dissimilar to the originals) and a fixing bolt, only one original having survived. The hole in the Debrie arms was too big, so I made sleeves that were a force fit. The addition of a locating pin for fixing the arms in place (like many 9.5 machines) completed the basic arm. The difficult bit, of course, was always going to be the spool spindles. For the front arm, I re-used the tensioning arrangement from the Debrie and used a "dog" collar as per the original, with lugs to engage the corresponding slots in the spools. This collar, which I suspect may have come from a KOK, had been re-used in the bodged arms the machine came with. The rear arm just needs a pulley, which again I had to make. However, there was a wee snag.

 This pic from the American machine shown earlier shows how the belt to the pulley passes thru a gap in the rear mech   cover, with very little clearance to spare. On   the original machine, the arm is shorter than the Debrie arm, and slung very   low, so much so that I had to build a mini base to go under my own projector to stop my 1200' spool dragging on the deck.   The low approach also looked wrong with the longer arm, so I pitched it rather higher. Not that it would have made any   difference since, with the longer arm, there was in fact no position that would not involve the belt fouling the mech cover. Now I dislike the sort of bodgery that thoughtlessly files away the relevant part of the cover to overcome the problem. I don't like changing the original as you know, especially when it ent mine anyway. Pix 3 & 4 in row 2 above shows my solution. At just the right point, there is a screw on the original which secures a clip that holds wires out of the way. The screw passes right thru the casting, so I could access it from the other side. It was a pretty fiddly job as space behind the gears was tight to work in. I even had to cut a slot in the threaded end of the rod carrying the pulley so I could get a screwdriver to it from the front of the machine - I just couldn't manage to screw it in from the back. I still have to complete the spool retainer etc for this lower reel as you can see.

The shutter was relatively easy as I have done this before and had a pattern to work from. The shutter is a bit larger than the original. I found with my machine that when I tried to use a short throw lens, the shutter could be seen on screen at the side of the pic. So I built an enlarged version, and it is a copy of this that I have made.

I have a fair bit more to do, and I spose there will have to be painting, which is always a chore. Will try to show you the final result.

           

 

Here are some pix of my efforts to make a new lampholder, as usual without changing the original. The original is on the left - a fairly standard small 2-pin bayonet. What here looks simple took a lot of doing in practice. I made an aluminium thingy, with a narrow tail that is a push fit into the lampholder. The other end I opened up big enough to take a standard halogen lamp base, which is held in place by grub screws either side. The lamp base had its wires cut off to only about 0.25" long. Two brass rods, with a hole drilled in the top to accept the lamp base wires, were soldered to these tiny bits of wire. These brass rods pass thru holes in a "plug" of PTFE. The holes at the bottom end of the plug (which incidentally is held in position by another grub screw) fit over the bayonet pins of the original base. Everything has to be just the right length so that when the new lampholder is inserted into the old, the brass rods make contact with the bayonet pins. 

I had terrible trouble ensuring all the connections were right and circuits complete. I kept getting on/off readings from my multimeter and couldn't get consistent results. First I found that one of the the crocodile-clip jump leads I was using to make connections was dicky. Then a plug with just a couple of inches of wire left in, cut off some elderly machine or other, proved faulty and had to be re-wired. Finally I found that the battery in my meter was low and just didn't have the oomph to push a signal thru. All this seems a bit unfair: I think THINGS may be against me - they certainly know how to make life difficult.

Now for a huge SMUG. I keep reciting my mantra - never throw anything away - to 'er indoors, who is a cynic in these things. One thing I saved was the lampholder from an ancient - 40 year-old - floor lamp from Habitat. Just a standard "spotlight" from the days when we didn't have proper spotlights or bulbs, ie a big bit of tube for the (perfectly standard) bulb, with a narrower bit of tube attached to hold the bayonet base fitting. It has proved to be the perfect thing for the Premier lamphouse.

 

What you see here is the original lamphouse back cover on the left. When it came to me, the mirror was secured in place by 3 screws. To these I added small strips of metal to bring the outside diameter up to match the inside diameter of the ex-Habitat lampshade I told you about. The screws make it too wide, so filed slots in the rim of the Habitat lampshade allow it to be inserted. It's a slightly loose fit, enabling the lampshade to be rotated a bit so the back cover can't fall out. When fitted, any looseness of fit vanishes, with the lampshade going on the outside of the front part of the lamphouse and the "legs" of the back cover inside. 

It's not a particularly satisfactory set-up for two main reasons. First, the only ventilation is in the gap between the lampshade and the back cover. Second, the front part of the lamphouse is basically just a 1" or so wide strip of thin metal that is not even a complete circle, because it isn't wide enough to get past the lamp housing. It needs a good test run with the 12v 100w lamp I propose to fit.

 

Now the wiring. Among the pix at the start of this particular section on Premier 3 is the flash-looking switch. Here are the outer casing and the actual switch from inside on which I have been working.

                       

 

The original function was simple; both motor and lamp were fed with 110v which, in the case of the lamp, passed thru the external resistance on the way. Only three circuit connections were needed - live to motor, live to lamp and common neutral. There does not appear to have been any interlock - burning the film was avoided simply by swinging the lamphouse back out of the way. No earth, of course.

 

The circuits passed across the body of the switch in thick brass strips. Pic 2 shows the common from one side (let's call it the rear), which I have removed for reasons that I will explain. I decided to go for completely separate lamp and motor circuits and to add an earth, requiring 5 links altogether. Pic 3 shows the front of the switch. Originally, there was a single brass strip, marked "LINE", running across the bottom of the pic, providing a common connection to the two switches. What I have done, slightly against my normal approach tho' it could be reversed fairly easily, is to cut thru the line input and add a strip of black insulation. A second wire then leapfrogs to provide a separate input to the second switch. Note that the output from the second switch is marked "LOW"; the output from the first is labelled "MEDIUM", (tho' it's hidden under the insulation). Don't know why. The green insulation strip I added to make sure my second input could not short-circuit.

 

Note that the green insulation and the new feed to the second switch are held in place by screws. At the end of the short line indicating the output from the first switch you can see the type of fixing used in the construction of the switch. It's a sort of hollow rivet, peened over at each end (you can see what I mean by peened in the pic). Happily, it is possible to just screw into the holes a small screw of the right size that will cut its own thread and provide an adequate fixing as long as you don't want to keep undoing it. (I did and had to use some solder.)

 

Now to the back of the switch (pic 4) where the common return shown in Pic 2 used to be. This common line was held in place by a screw passing thru the body of the switch into a threaded hole in the little lug visible at one end of the strip. What I have done is to take a strip of Paxolin board and fix brass strips to it to provide the three circuits I need, held tenuously in position by the same screw thru the body of the switch into one of the brass strips. Most of the holding in place is, of course, done by the outer casing of the switch. You can see I have wired one end of the switch, adding a further bit of insulation to be on the safe side. I just hope it all fits back inside the casing!  

You will observe that this set-up provides neither lamp/motor interlock nor motor speed control. There is a brake-type speed control on the projector, but I'm not keen on these. What I propose is to provide both these facilities on the power supply - the switch is there more to look pretty and original.

 

You may recall I mentioned I had to fit an extra roller to avoid the take-up belt fouling the mech cover at the back of the machine - 4th October again. However, I then found that the wiring at the base of the lamphouse was so bulky that not only would the film foul it with my new spool arms but, I suspect, wouldn't have worked even with the original arms. The wires from the lampholder were just about 2" long before a join was made by twisting the ends of the wires together with the ends of the wires extending the circuit to the switch and then screwing a plastic thingy with an internal metal thread over each of the the joints. A crude and bulky approach.

 

This challenged my ingenuity, of course. I found that the machine had fixed rear feet but that these had been altered (not terribly well!) to raise the rear of the machine by about 0.5". I could understand this, as I have found with my machine that when using a 1200' reel, it touches the surface on which the projector stands and stops the take-up. I just made a shallow wooden base for mine. Anyway, this gave me the idea of using the rear feet to attach a bracket with an additional roller to overcome the problem. Here is the result.

          

  

I have also added a steel base-plate; the original cover is just a sheet of stiff insulating card and over time has become very buckled and battered - the steel plate tidies it up and stops the wires bending it where they emerge from the holes in the side of the base. These are open-sided, leaving the card base to do a job it just isn't strong enough to do (tho' I have left it in place for insulation). Regular followers will be unsurprised to learn that I have since re-done the wiring so that my extra roller probably isn't needed..........

 

Just a shot now of the projector base wiring in progress.

 

As you can see, the base is very shallow and I was lucky to have to hand a shallow terminal strip. The wires you see joining the RH side of this strip are from the lampholder. The only authentic-looking wire I have to hand (it's almost impossible to get) is a bit thin so I have doubled up for the lamp. This wire isn't too bad, but I have another even thinner type which is horrendous - the moment you cut it, the woven outer cover starts to unravel and rapidly becomes almost unmanageable. It's a struggle to get a bit of heat-shrink tube across the unravelling end to sound material to stop the rot spreading.

 

I have had to make a few changes in the light of experience and testing. The bracket holding the additional guide roller had to have some metal removed to allow the big retaining nut for the bottom spool arm to be loosened sufficiently to move the arm to the "folded" position. Even now, complete removal of the arm will require the fixing bolt, which passes thru a threaded hole in the main body, to be undone at least partially. I have also modified the roller itself, by making up two much bigger side cheeks to prevent the film coming off the roller. The original body of the roller remains, but with its ends cut off, so we now have a three-part roller.

The other big change was the lamphouse. I mentioned that the front part of the lamphouse was a rather flimsy not-even-complete circle of metal. I have replaced this with something much more robust, and also adjusted the rear part to bring the mirror closer to the lamp. I have inserted, as I mentioned, a 12v 100w lamp for the time being, because of the problem of lack of ventilation of the lamphouse. I suppose it could be possible to do more on this front, but I have to stop somewhere and move on to my many other projects. The big 5-core cable from the machine, via the switch, now terminates in a kind of "Y" lead, with a three-pin connector for the motor plus earth (I realised when writing this that I had not connected the earth terminal to the chassis, so had to remove the base plate for the thirtieth, or possibly fortieth, time to do so), and a 2-pin for the lamp. The cable is more than capable of handling a much more powerful lamp if required. 

This leaves the question of a power supply. I have described elsewhere how I mounted a Eumig P8 tranny in an old 50v 200w tranny box which once powered a 200B with that rating of lamp. This gives 12v and 110v, although I have never been wholly happy with the 240v mains, 110v and 12v neutral wires all meeting at the same terminal. This is partly why I have made completely separate circuits for lamp and motor.

However, I didn't fit an electrical speed control and this machine definitely needs one, unless one is content to use the original friction brake. It might also be useful to have an interlock arrangement for the lamp and motor. The original does not seem to have had one and has a printed warning on the lamphouse to avoid subjecting the film to the full power of the lamp. This seems to have been a common enough arrangement (also seen on the Victor 28), with the lamphouse made to swing back without taking the back leaf of the gate with it. I would envisage, basically, leaving the original switches in the "ON" position and controlling everything from the power supply, with maybe a lighting dimmer as a motor speed control.

Another thing I had to do was swap the spring drive belt the machine arrived with for a rubber one. The motor on this machine is mounted on a bracket which leaves it free to pivot, at least within the confines of the aperture it occupies. The weight of the motor acts by gravity to provide the necessary tension to the drive belt and, I would guess, a degree of flexibility to absorb the sudden pull as the motor starts. However, the spring belt wasn't doing a very good job, because it had too much spring or stretch in it. Every time the motor was started or stopped, the motor would thump against its aperture. The rubber belt is fine.

The final thing left to do, of course, is the painting. This is really a summer job and is going to have to be deferred.

 

Here now are the pix of the final result and some of the changes I have described. Note it has a 1200' take-up spool, which also fits the original arms like on my machine.

                       

  

Pic 2 shows a close-up of the "Y" lead I made - I split the cover to get two wires out, sealing up with heat-shrink plastic then coating the whole lot with liquid rubber insulation. I was so pleased with the result that I applied the liquid rubber to one of those B&H moulded-on tranny plugs that was threatening to "fray" even more. The same pic shows the improved rear pulley arrangement. I thought you might also like a close-up of the mech, too (pic 4), which shows what I did with the lamphouse. I have included pic 5 just to show how the heavy cable is looped round and secured.

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Yet another Premier! I thought they were rare!

 

There are clearly highly skilled and determined people out there. Dominique Dalmar from France has sent me before and after pix of a 28mm Pathescope Premier. What an amazing transformation!