Bronica GS-1 Interlock Pin issue

I recently took my GS-1 on location and connected a loaded film back and
it would not fire. I took off the film back and tried it in multi exposure and it fired just
fine. In single exposure mode with the film back off. I took a paper clip and pressed
in the interlock pin in the camera and it cranked and fired fine. So no issue with the
camera. At the moment I only have one film back, so I could not try another.

I checked the film back which has 2 interlock pins, one in the outer case, and
one in the film cartridge. There is a small lever on the side of the inner film cart that when
pressed, extends the pin. I wedged a small piece of metal against the lever to keep the pin
extended, so I can try it without wasting more film. I inserted the film cart back into the outer
film back and attached the film back to the camera. Still nothing. The film back pins were not
pushing the camera pin in far enough to unlock the shutter release. (again when the camera
pin was pressed in with a paper clip, the camera unlocked and fired and the film lever could be
advanced) .. So I took the film back off and removed the outer pin, it looked like it was not long
enough for all 3 pins to properly push all the way in to unlock the camera.

So I took a tiny finishing nail that was the same width of the pin and I cut it to be slightly longer then the pin.
I put the new pin in the slot, reattached the film back and it now works with no issue..

I'm wondering if the outer pin wore down after years of usage?

I read on another forum about a guy with an ETRS that had the same issue. But in his case, he
just extended the pin on the inner Film Cartridge and it worked. For me I actually had to go one
step more and make a new outer pin as well.

Has anyone who uses Bronica, had or seen this issue before. As much as I love the Bronica
cameras. This whole interlock pin design is completely stupid and should have not been on
these cameras. Just another thing to go wrong.

Now lets see about getting your problem fixed.

I had a similar issue on my GS-1, but not exactly the same; it was on a lens contact pin.

I'm assuming your camera/back has worked for you in the past.

To avoid wasting film while your testing you could just load some old 120 backing paper so the back thinks it has film in it.

Do the pins look worn? Also make sure nothing is keeping the back and insert from seating firmly their respective places. I've found it easy to almost fully seat a back without it completely engaging, with no mechanical faults, but enough for the camera to not work.
Also work the latching lever when you attach the back, which makes it seat better.

Check the interlocks for the dark slide as well - the issue could be there instead of the camera-back interface.

The back clasping mechanism on mine went bad causing similar issues and I had to have the body serviced. The tiniest gap can prevent things from engaging.

Back to the pin and receptacle (socket). Use an object like your paper clip and _gently_ exercise the sockets and any pins that are supposed to move. If it has been sitting a while things may just be sticking a bit. That's what I did for my lens contact pin and it has been fine for years.

Thanks for your comment... As I said, with the new pin it is now working. I did move the pins back and forth with the paper
clip, just like you suggested. The film back clasps on to the body with no issue. I tried all that you suggested, before modifying
the film back. Like I said, I wedged a tiny piece of metal against the lever on the side of the inner film insert to keep the pin on
the inner insert extended. So It will fire with no film in it. But even with that, with the original pin on the outer part of the film back,
it still wouldn't work. I tried it several times and also removed and reattached the film back several times to make sure it was coupled
properly to the camera body. It seemed like the 2 film back pins were not pushing the camera pin in far enough to unlock the shutter
and film advance. So I took a tiny finishing nail that was the same width of the outer film back pin and cut it to be slightly longer and
replaced it with this new pin and now it works.

The easiest fix for this would be to just to get another film back as I think the film back was the issue. But as of lately the only film backs Ive
seen are on eBay all by Japanese camera sellers and they asking high prices. So until I end up buying another film back. I wanted to be able
to use the camera.

Truzi said:

I had a similar issue on my GS-1, but not exactly the same; it was on a lens contact pin.

I'm assuming your camera/back has worked for you in the past.

To avoid wasting film while your testing you could just load some old 120 backing paper so the back thinks it has film in it.

Do the pins look worn? Also make sure nothing is keeping the back and insert from seating firmly their respective places. I've found it easy to almost fully seat a back without it completely engaging, with no mechanical faults, but enough for the camera to not work.
Also work the latching lever when you attach the back, which makes it seat better.

Check the interlocks for the dark slide as well - the issue could be there instead of the camera-back interface.

The back clasping mechanism on mine went bad causing similar issues and I had to have the body serviced. The tiniest gap can prevent things from engaging.

Back to the pin and receptacle (socket). Use an object like your paper clip and _gently_ exercise the sockets and any pins that are supposed to move. If it has been sitting a while things may just be sticking a bit. That's what I did for my lens contact pin and it has been fine for years.

Click to expand...

Ya, prices have really gone up lately because of the film resurgence. I was lucky to get my setup years ago when backs were $50 - $75 each. Hopefully it is the back and not wear in the body itself.

Make sure to test with an unimportant roll first.

Currently some nice condition used 6x7 120 backs in the range of $150--better than the KEH price, though shipping is a bit high from Japan, but not extreme.

MF equipment in good condition is no longer dirt cheap. There is less of it every day, and prices reflect this.

Are you CERTAIN that the film is properly loaded into the film insert? If you removed the film blind from the back, you should see emulsion, not paper, if loaded properly.

The pin that protrudes from the metal cylinder to contact the corresponding mechanical 'sensor' in the body will normally come out WHEN the film is ADVANCED...it is how the body knows there is a fresh frame ready for exposure (unless the multiexposure lever is active).

Yes Ive been shooting film for 36 years. I know how to load a film back... The film was loaded proper.

Did you read my original post? There are 3 pins, One in the camera body, one in the outer film back
and one in the inner film insert. As I said twice in this thread. There is a lever on the side of the film insert,
once depressed, it extends the pin in the film insert which in turn pushes the pin in the outer film back (metal
cylinder) and that pushes the pin in the camera body and that in turn unlocks the shutter release and film
advance. So I didn't have to waste more film. I took a tiny piece of metal and wedged it against the lever in
the film insert to keep the pin extended. So technically this should let the camera fire with no film in single
exposure mode. I tried it and nothing. The pin in the camera was not being pushed in far enough. So I took
the pin in the outer film back out and it looks too short, not sure if its worn down from use? I made a new
pin that was slightly longer and put it in the metal cylinder. The camera now fires even with no film in the
film insert. So the way I see it, is the problem was the film back. I read on another forum where a guy with
an ETRS had the same issue.

I was just asking if any other Bronica users here have encountered this problem?

wiltw said:

Are you CERTAIN that the film is properly loaded into the film insert? If you removed the film blind from the back, you should see emulsion, not paper, if loaded properly.

The pin that protrudes from the metal cylinder to contact the corresponding mechanical 'sensor' in the body will normally come out WHEN the film is ADVANCED...it is how the body knows there is a fresh frame ready for exposure (unless the multiexposure lever is active).

Click to expand...

Carlini Fotograf said:

Yes Ive been shooting film for 36 years. I know how to load a film back... The film was loaded proper.

Did you read my original post?

Click to expand...

I did read your post, I merely was asking a question about an error that can be made by those not really familiar with Bronica film insers...I have made that mistake myself, as a new owner of the Bronica ETRSi system which I bought almost 30 years ago....when the film is loaded wrong, the pin does not come out to press into the body far enough....the body knows when a new frame is in postion, so it prevents exposure (unless multiexposure control is set) I have experienced a different kind of problem with a used back, when the pin stuck into the body too far! It had to be repaired by Bronica.
That is why I inquired. Your OP gave no clue as to your familiarity or not, I was not trying to insult your intelligence, I was trying to help...Sorry I tried!

Wiltw Thank You for your comments. I'm sorry if I seemed gruff with my reply. You are right,
Ive been a long time lurker here, and just started posting and you don't know my level of
experience with photography or medium format cameras. I'm sorry that I didn't make that
more clear in my original post.. I appreciate you trying to help. By the way what you said a
bout the Bronica's is all correct. But even with the film loaded properly on mine, it still wasn't
pushing the pin in far enough. I'm just wondering if it is at all possible for the pins to wear down
in time with lots of usage?? I made a new pin that is slightly longer then the original and now the
camera fires just fine. Anyway Thanks for the your help....

PS.. I personally think this whole interlock pin design is stupid and should never have been included
on these cameras....

wiltw said:

I did read your post, I merely was asking a question about an error that can be made by those not really familiar with Bronica film insers...I have made that mistake myself, as a new owner of the Bronica ETRSi system which I bought almost 30 years ago....when the film is loaded wrong, the pin does not come out to press into the body far enough....the body knows when a new frame is in postion, so it prevents exposure (unless multiexposure control is set) I have experienced a different kind of problem with a used back, when the pin stuck into the body too far! It had to be repaired by Bronica.
That is why I inquired. Your OP gave no clue as to your familiarity or not, I was not trying to insult your intelligence, I was trying to help...Sorry I tried!

Click to expand...

Carlini Fotograf said:

PS.. I personally think this whole interlock pin design is stupid and should never have been included
on these cameras....

Click to expand...

Bronica interlocks are there for a purpose, which all make sense to me as screw-up-prevention..

• No removal of dark slide if back not mounted on body
• No firing of shutter if dark slide is in place
• No shutter fire if film not advanced to a new frame (if multiexposure is not active)

On the ETR series, those three things are accomplished with only two interlock pins, and I do not know of a third pin on a GS-1

There are 3 Pins on the GS-1. One in the Film Insert, One in the outer Film Back (Metal Cylinder), and One in the camera. There is a lever
on the film insert that when depressed, Extends the inner pin, which then pushes the outer pin (Metal Cylinder) which then pushes the pin in
the Camera. I wedged a small piece of metal against the lever to keep the inner pin extended with no film in the insert. I made a new pin for
the outer back,and with that, now the camera fires in single exposure mode. It even fires in Single mode with no film in it.

wiltw said:

Bronica interlocks are there for a purpose, which all make sense to me as screw-up-prevention..

• No removal of dark slide if back not mounted on body
• No firing of shutter if dark slide is in place
• No shutter fire if film not advanced to a new frame (if multiexposure is not active)

On the ETR series, those three things are accomplished with only two interlock pins, and I do not know of a third pin on a GS-1

Click to expand...

I do like the cheap and effective repair , makes my Scottish heart smile . Peter

wiltw said:

Bronica interlocks are there for a purpose, which all make sense to me as screw-up-prevention..

• No removal of dark slide if back not mounted on body
• No firing of shutter if dark slide is in place
• No shutter fire if film not advanced to a new frame (if multiexposure is not active)

On the ETR series, those three things are accomplished with only two interlock pins, and I do not know of a third pin on a GS-1

Click to expand...

He's claiming both sides of the mechanism for the film-back interlock as two separate interlocks. Instead of using one very long pin that would get bent and broken on a regular basis, Bronica uses a pin in the film insert to operate the pin on the film back, to tell the camera whether the film back is ready to take a picture. But since neither side does anything on it's own, it's only one mechanism.