Filmo 70-DR Trigger Issues

Matthew Hall · November 12

I guess this is mainly for Simon as you helped me get this camera up and running in the first place (although I welcome anyone else with comments).

I have discovered what I think is a problem with the trigger button on this camera. Normally when you are shooting and stop before the spring is completely unwound, the trigger button will pop out and you hear an audible click as it returns to its rest position. This resets the stop pin in case you turn the turret to a lock position. When set to a run position the internal stop pin resides in a depression in the back of the turret which allows the trigger button to be depressed, etc. I have found that if I let the spring completely unwind, when I release the trigger button it does not pop out as far and there is no click, indicating the stop pin has been re-set. At that point if I turn the wind lever to load the spring the camera immediately begins to run on its own, even if set to lock position on the turret or I have not pressed the trigger button. As it never completely popped out before, the trigger thinks it is still being depressed so the camera runs. If I stop shooting the camera "before" the spring is completely unwound, the trigger will always pop out completely and this is never an issue. As long as I never let the spring completely unwind, the camera functions as normal. It appears that the trigger button needs the force from the spring to properly re-set itself to the correct position. Is this normal or is there something wrong here?

Robert Houllahan · November 13

They stick sometimes, you can remove the whole front with the shutter and turret (carefully) and clean the button and apply some lubricant to the gear and under the shutter button and they tend to run right and stop right again.

I just did this to a 70DR I bought that appears to be basically new and never shot it was stuck in position for 40-50 yrs it looked like and now it runs great. There are also some clearly marked oil spots inside the camera.

Simon Wyss · November 13

11 hours ago, Matthew Hall said:

It appears that the trigger button needs the force from the spring to properly re-set itself to the correct position. Is this normal or is there something wrong here?

The assumption is correct. The stop hook is a passive connecting part, it stands close to but free of a recess in the main group on one side, in the groove of the release button on the other. Spring force turns the main group and thereby pushes on the hook at a certain point. That helps the release button up.

As Robert says it’s not wrong to clean everything but I do not lubricate the release buttons. Less is sometimes more.

Matthew Hall · November 14

So it is best to always have the turret set to the "run" position when winding the spring from a completely exhausted state. That way the release button will always "set itself" to the correct position.

As the turret with my camera is not original (mine has no gear teeth to mesh with the viewfinder turret), I feared that maybe it did not quite have the proper dimensions to reset the trigger button correctly. I was experimenting with different thickness washers under the turret to see if that would solve the issue. It either did not help or made things worse. I have now ordered a new cast turret from Magna-Tech with the proper gearing so the finder turret will turn in unison with the taking-lens turret. Thanks again.

Matthew Hall · November 23

I am still having issues with the trigger not resetting after the spring is completely unwound. It works fine when the turret is set to the "run" position -- when I turn the key to load the spring the trigger immediately pops out and locks. But when the turret is set to the "lock" position and I turn the key to load the spring the trigger button does not pop out and the camera immediately begins to run as the trigger is not properly reset. I have to always start the camera winding process with the turret in the "run" position to get it to work properly. I have removed the turret and cleaned everything yet it still happens. It doesn't make sense that it works with the turret in one position but not another. Any ideas?

Simon Wyss · November 24

You have that bolt in a leaf spring with tongue. The tongue falls into recesses of the turret for RUN, if I remember correctly. This group should function faultlessly, may need cleaning and a little grease.

Matthew Hall · November 24

The camera does work flawlessly when set to the RUN position. When loading the spring after completely unwinding, the trigger button pops out into position awaiting to be depressed and start the camera. The problem happens when attempting the load load the spring after completely unwinding when the turret is set to the LOCK position. Upon turning the spring wind lever the trigger button does NOT pop outward and upon release of the wind lever the camera starts to run until the spring is exhausted. I believe that the stuck trigger button does not allow the stop pawl assembly to reset to the proper position to lock the gear assembly for activation by the trigger button, hence the camera begins to run immediately.

I have the front plate removed from the body and run a few manual tests to confirm this. With the front plate in position on the body I let the camera run until the spring is completely unwound. Then I use a flat bladed screwdriver to depress the leaf spring into the position it would have when the turret is in place and set to the LOCK position. While holding the screwdriver in place I turn the wind lever and the camera starts to run as soon as I release the wind lever. The trigger button never pops out to reset the stop pawl assembly properly. I understand that the plunger on the leaf spring is designed to keep the trigger button from being depressed when the turret is set to the LOCK position, but it appears, at least on my camera, that it also keeps the button from rebounding outward.

I have a second 70-DR which I recently acquired and this problem does not present itself with that example. When attempting to wind the spring with the turret set to the LOCK position, the trigger button always pops out and resets the stop pawl assembly to keep the camera from running until release by the trigger button.

Upon further review I believe I have located the source of the problem. The trigger button has two major recesses in the shaft. The one at the far end is used by the stop pawl to release the camera for operation (and to keep the button from being ejected by the spring). Then there is a larger recess up the shaft used by both the leaf spring plunger and the stop plunger (used to keep the button depressed for long operations and to keep the button from being depressed in the LOCK position). If you look closely at the photo I included of my trigger button you will also see a minor shoulder on the shaft just above this recess. I have also included a photo taken with the front plate removed and the button inserted. You can just see this shoulder in the hole where the leaf spring plunger would sit. I believe that this plunger is getting caught on this minor shoulder of the shaft, preventing it from releasing the trigger button when the turret is set to the LOCK position. If I lift the screwdriver just a fraction of a mm the trigger button will pop out correctly and stop at the ready position.

NOTE: I just acquired a copy of the B&H service/repair manual for the Design 70 Cameras (DA, DL, H, DR and the HR models). The back half of the manual also incudes a complete listing of all the parts to each camera and which ones will fit into which models. The camera I am having the trigger problems with is marked as a 70-DR model, yet the turret installed has no teeth to engage with the viewfinder turret. Simon previously mentioned that this turret had likely been a revision to this camera, swapped out at some point after purchase. In the parts catalog included in this manual it shows the two turrets. The toothed turret is listed for use only with the DR and HR models. The non-toothed turret (which is installed on my 70-DR camera) is listed for use only with the DA, DL and H models, but NOT for use with the DR model. Is it possible the the rear spacing which presses down on the leaf spring plunger is different for these two turrets and is placing too much pressure on the one in my camera when in the LOCK position so it cannot release the trigger? It is just enough to get caught on that minor shoulder previously mentioned on the trigger shaft.

Matthew Hall · November 24

Matthew Hall · November 24

I don't know if this affects the trigger mechanism and is causing the problems I am experiencing, but I have discovered something about the history of this camera. It came with a 115 volt motor attached, which as Simon pointed out indicates that this was an indoor camera, likely used in a studio setting. The question that I have always had was why the turret exchange? What was the desire to dis-engage the lens turret from the viewfinder turret? Well, I have found a few clues on the body of this camera that point to an explanation. I noticed that a hole has been drilled into the side of the turret. Upon inspection using a loop it appears that this hole is also threaded. I then looked at the front plate and noticed an indentation in the side of it that corresponds to the hole in the turret. As you can see in the photo, when the hole and indentation are aligned, the turret is lined up with the shutter as when set to the RUN position. This small indentation was apparently made by a set screw (or grub screw as some call them). Whoever was using this camera did not want the turret to be rotated and apparently made sure that this could not happen (although notice the line on either side of the depression indicating that the turret was turned slightly with the set screw still protruding a bit. This line is only directly on either side of the depression and does not run around the front plate). Likely this was used with only one lens and did not need the option to rotate to various other focal lengths. The reason for the turret swap is now obvious. The toothed turret is MUCH thicker at the edges to accommodate the toothed notches, and as such it would have been impossible to drill the small hole for the set screw as there was just too much metal to deal with. The non-toothed turret has a thin wall perfectly suited for this set screw.

So what we have is a camera that was used in a studio setting, with just one lens, set to a particular setting and never changed. The internal gearing in this camera show little wear and it runs extremely quietly. So it does not appear to have been used extensively and worn down, as one might expect from a commercial setting in which this camera apparently existed. What this was used for may never be known but it is interesting.

Edited November 24 by Matthew Hall

Matthew Hall · November 25

After playing with this a little more I have discovered that if I tighten the nut on the turret just hand tight, and by that I mean snug but by no means tight, I can get the trigger button to function properly in the LOCK position when tensioning the spring. It will pop out and lock so you cannot depress the button. If you loosen the nut even slightly, the button will pop out but you can depress it and the camera will run in the LOCK position. Tighten it just slightly and the button will not pop out and the camera instantly begins to run as soon as I release the winding lever. So there is a very small range of torque on the turret nut that will allow the camera to function correctly at ALL settings, but it is incredibly narrow. I also feel that the nut is so loose that it will begin to loosen further by itself after just one or two rotations of the turret. I guess I could put some sort of locking compound on the nut to keep it from turning (or remember to never turn the turret counter-clockwise), but just make sure that none gets down the oiling hole in the center of the axle.

I feel that the proper solution is to get the correct turret for this model. I need the 70-DR version that has the toothed rim as that is the only version rated by Bell & Howell for this model. The one I have installed just seems to have a clearance issue with the plunger located in the leaf spring assembly. I have tried using various thickness washers under the turret to give it slightly more clearance to allow the plunger to pop up enough to release the trigger button but none have worked with consistent results. The service manual even states that the front plate and stop pawl assembly are different for the DR/HR models vs. the DA/DL/H models. So if I have a DR front plate/stop pawl and a DA/DL/H turret (which it appears that I do) the book says it work work properly. Actually it's kind of cool . . . . I found a way to get them to work together. It is not an effective method, but it will work, just under very limited conditions.

Edited November 25 by Matthew Hall

Simon Wyss · November 25

Thanks for the photos

Now I see that this was a -R turret the teeth turned off. The earlier turret is a piece of sheet steel drawn or pressed to the form, lacquered over.

(the R stands for Revolver, in German; another Bell & Howell secret that puzzles me; K stands for Kassette, also in German, meaning film magazine; I continuously do research on the company and its products; it has perhaps to do with Bruno Stechbart, a Polish-German immigrant and B. & H. assignor)

My English is not as precise as I wish it were. If I can put it like that: let the release plunger roll over a smooth flat surface such as a pane of glass or a measuring stone. That way you can detect hickups, bumps, nicks. This is a chromium plated brass part, if I remember correctly, so it’s wise to smoothen it out non-abrasively. The shaft of a screwdriver can be used or a pin driver’s. Work it over the burr in order to form the metals back to shape. Check, repeat until satisfactory. The bore in the camera frame can also be ironed out a little, the combination of both sides should give the desired result. As already said, less (to one side) is often more. Work to the main frame should be done away from the innards. —— Right, everything should be removed from it. 🤪

Matthew Hall · November 25

So I did as you suggested and cleaned and rolled the release plunger. I detected no burrs or bumps but did as you suggested. Then after removing the inner mechanism I worked on the bore hole as well. Again, did not detect any burrs or rough spots. Put it all back together . . . no change.

So, one of my cameras works and the other one does not, so there must be a difference between the two. Time to rule out which parts are not at fault and the one left over must be the guilty party. I switched turrets and placed the cast toothed one onto the camera with the trigger problem (the cast one is 100% functional on the other camera, release plunger and all). After swapping turrets I tested again. Even with the turret that works on the other camera, the release plunger is still not working. So the turret is NOT the problem. I then decide to swap out the leaf spring/plunger assembly to rule that out. Viola . . . , the release plunger now pops out in the LOCK mode and will not release as it should. SO, this part is the problem.

I have included a few photos to illustrate what I found. The first image shows both cameras and their front plate. The one on top works 100% good, the one on the bottom is the problem. Note that the bottom one has no filter slot -- does that mean it is also not original to the body and may have been sapped out with the turret? The next several images show the two spring/plunger mechanisms. When laid side by side the mechanisms appear identical, But if you remove the plunger and stack them next to each other you can see a subtle difference. The plunger that works in BOTH cameras (the one on the right) is slightly longer than the other one. It is minimal but I can visually see a difference when held side by side. Short of obtaining a new part I don't know how to fix this.

Edited November 25 by Matthew Hall

Simon Wyss · November 25

Really good work. I think you nailed it entirely. It’s now about either finding a replacement plunger or making a new one/have one made that is long enough. MTE may have spare parts.

Matthew Hall · November 25

Well, you will all probably laugh at this but I have solved the problem, using brute force. The plunger in the mechanism not working was just slightly too short. Turns out it is from a camera with serial #K17498, an older camera which might account for the wear. I was able to lengthen it just enough so it would function using the following method. You can see what I am talking about in the photo included below (please excuse the crude drawing). I supported the center of the plunger on a piece of steel while positioning a screwdriver directly above this on the opposite side. A couple of strong impacts on the screwdriver put a mild "dent" in the center of the shaft without bending it (hence the support from below). By creating this dent it lengthened the shaft slightly. Turns out it was just enough to get the assembly back to functional order. I double checked that the plunger rode smoothly in the bore hole before final assembly. The release plunger now pops out just like it should in the LOCK mode and cannot be depressed until the turret is turned to the RUN position. I know the repair it is a bit clumsy but it worked! Both cameras are now working as they should. I don't think the dent I put in the plunger shaft is enough to weaken it so it should last for awhile longer. I guess time will tell.