Bronica SQ-i back problem

[Usagi]

Hi,

One of my SQ-i backs failed couple of days ago. The problem is that roller (and it's axle), marked in the red arrow in first picture, does not turn the sprocket marked with red circle in the picture.

In normally functional film back, when the roller on the film roll 'begin' side is turned, the sprocket at the end of axle will always turn also. This movement advances the picture number counter.

In that faulty back, counter does not advance and thus the back will never go in the 'cocked' state. The camera crank simply winds whole roll...

This is how far I have figured everything out. My problem is that I don't know how I should fix it.

I think that originally the axle inside the roller (second attachment picture shows the roller and it's axle. The sprocket is marked with a red circle, like is it's place where it is in the first picture) is either glued or tightened using small screws that are in the holes pointed by red arrows.

But this all is based on my theory that axle must be fastened to the roller.

So how it is? :confused:

 

[awldune]

I have an ETRS insert with the same problem. I haven't opened it up, but I studied the operations closely.

When the (properly functioning) film insert is not mounted in a back, the roller turns freely without advancing the counter. The counter advance seems to be controlled by a lever/switch that is depressed by the shell cover when the back is closed. I would check there to see if there is a weakened spring or bent/misaligned part.

I don't think the axle is supposed to be rigidly attached to the roller, although I suppose it might need to have more friction than it currently is producing. Did you determine whether there are screws in the holes you indicated?

 

[Usagi]

Yes, there are screws.
Yesterday I bought small screwdriver (1 millimeter) and tightened the screws a bit. Now it works

As far as I understood the mechanism, when the insert is not mounted in a back, roller turns freely as the gearing where roller's movement is transferred via the sprocket on it's end is in 'free' position.
When the lever/switch is depressed by the shell cover like you described, the gearing is attached to the roller's sprocket.

So far I have tested it only with empty roll (only back paper) but it seemed work as it should.
Now there's test roll on the way so soon I will know if there's some malfunction still.

 

[awldune]

Hmm! Maybe all my insert needs is for me to tighten the screws, then. I'm surprised that this isn't common knowledge to Bronica users. The Bronica discussion pool on Flickr didn't seem to have a clue and just said I should get a new back.