A little technology

Repair is a profession...

It's also a passion

The purpose of this page is to explain a repair procedure.

I decline all responsibility if you break your beautiful toys... That's it!

Replacement of curtains

Generally speaking, the procedure for changing curtains is always more or less the same.

There are a few important points to remember for shutters with horizontal curtains:

1/ When removing the old second curtain, mark the position where the second curtain is glued to the large drum.

2/ When removing the old ribbons, mark the positions where the ribbons of the first curtain are glued,
located above and below the large drum.

3/ When cutting the new curtains and tapes, the lengths must be scrupulously respected and, of course, the tapes must be re-glued according to the marks made when the old ones were removed.

4/ Worth knowing:

This bonding is essential compared to the bonding of the drums used to provide tension.
Logic dictates that it is the accuracy of the bonding of the second curtain and the tapes of the first curtain to the large drum that determines how well it works.
The tensors are used to determine the accuracy of the travel time of each curtain.
The position of the adhesive on the tensors is unimportant, since all they do is “stretch”.
However, it is important that the position of the tapes on the second curtain and the gluing on the first curtain allow the curtain to be
without the slightest vertical shift.
This method ensures precise parallelism between the metal ties (where the curtains are fixed) and the edges of the display window. (If it’s crooked, it’s no good…)

5/ Next, you need to apply a “base” voltage so that the shutter works.
To do this, set the camera to B exposure, release the shutter and hold it down.
Adjust the tension of the first curtain so that it snaps into place (closes completely) and add two or three turns maximum.
and add two or three turns maximum.
Release the shutter release and adjust the tension of the second curtain so that it also snaps into place, adding two or three turns, always at the maximum.
If the tension springs are not tired, their actions should be identical.
Logically, the shutter should ‘sound’ as it does for 1/15 second.

Basic curtain tension is covered on this page: Basic tension

6/ For precise adjustment of curtain translation speeds, the use of a shutter tester is essential.
In most cases, it is +/-12 ms.
Next comes the adjustment of shutter speeds (that’s another adventure).

7/ Each brand has its own specific way of setting fast and slow shutter speeds.

8/ The biggest mistake when a shutter malfunctions is to ‘tighten’ the curtains.
Each curtain should move at the same speed or as close to it as possible.

9/ Reflection: It’s important to understand that the shutter is a slit between the curtains that covers the format,
which fully justifies the fact that the shutter speed must be the same throughout the journey in front of the window.
This slit is narrow for fast speeds and wider for slow speeds.
(with the exception of slow speeds, which depend on the mechanical module… slow speeds, of course).

A gap between the curtains, caused by too much or too little voltage, will inevitably cause an error in the illumination of the film.

10/ Imagine: (action in slow motion…) You release the shutter, the first curtain moves off, a time X is selected by the speed selector, which determines the width of the slit,
This determines the width of the slit (here we are in the area of the space/time relationship).
The second curtain is released and together they travel through the exposure window, but the second curtain is out of adjustment
(too much tension, for example) halfway through, the second curtain has already caught up with the first by 40% and then, at the end of the shutter, by 70%.
if not 100% by halfway, resulting in half-printed negatives.

Shutter tester

Basic method