Bronica ETRS Shutter malfunction on 75mm prime.

[JohnRichard]

My Bronica ETRS has developed a strange issue. The battery is known good/new, and the camera did work well. However, now about 80% of the time when depressing the shutter trip button, the mirror will raise but
the shutter will not fire. Very slightly moving the lens will cause the shutter to fire for the correct time specified. Should I get a new lens? The contacts look clean, I have yet to try and clean them better.
At this point because all mechanical devices seem to work, I am leaning strongly towards an electronic fault. Any thoughts?

Thanks.

 

[Alex Muir]

There was a thread recently about SQ shutter issues. It may be worth a look. There was information about the shutter actuation mechanism which may be similar on the ETRS. Alex

 

[Fluidphoto]

My 150mm had the same issue. A good scrubbing of both the body and lens contacts with a soft pink pencil eraser seems to have resolved the issue. It's a good easy (cheap) place to start.

Ryan

 

[DWThomas]

Since the mirror raises, it is likely a problem in the lens. Trying another lens would be a good way to isolate the problem as to body or lens. That's one reason I have about 2.5 SQ-A kits on hand! The shutter, and a bunch of mechanics are in the lens, so it could be cleaning and lube time. But there are also some electrical connections in the lens that could have a problem.

There is some Bronica info at Buona Luce ("good light"!) that might provide some insight.

 

[JohnRichard]

Thanks gentlemen! I'll give these a try.

 

[lxdude]

It is almost certainly due to old grease in the mechanism that transfers the shutter release movement from the body to the lens. The shutter itself is not at fault and does not need to be touched. It is an easy fix. The dead giveaway is that it will fire if the lens is rotated/jiggled on its mount.

I've posted here on APUG regarding what it is and how to fix it, but I gave more thorough instructions here:

www.photo.net/medium-format-photography-forum/00bG13



This regards an SQ series lens, but the ETR series lenses have mechanisms which work the same way. I first discovered the problem and figured out the solution on an ETR series lens, a 75mm E-II in fact, so be assured these directions work for ETR lenses.

You will only need to remove the back plate to gain access to the places you need to clean and relube.

 

[JohnRichard]

Circled in red are the screws that I can not get to move. I don't really want to soak them in anything so I'll have to think of a way to go.
Thanks for all the help!

 

[lxdude]

You do not need to remove those screws. They hold rotation limiters for the focusing helicoid. You can do everything from the point in disassembly you have already reached.

In the instructions I linked to, I referred to the rollers and to the cam plate where it contacts the rollers as what needed to be cleaned and regreased.

See that short slot on the left of the picture, midway up? One of the rollers is clearly visible inside it. It is through that slot and its counterpart visible in the picture on the other side that you will reach the old lube to remove and replace it. When you look into the slots while rotating the cam plate you will be able to see the edges of the cam plate, which contact the rollers and move them outward, and it is those edges you need to clean and relube also.
Along the edges of the cover plate are two semicircular slots: the one nearest the camera is bordered by the row of soldered wires. Through either of those slots you can rotate the cam plate through its full motion.

 

[JohnRichard]

Thanks for the details! I THOUGHT those were grease points, but I'm no lens mechanic so I decided it better to ask. I was thinking from all that reading I needed to take that next plate off.
Lens repair underway. I'll let you know how it goes!

 

[lxdude]

Yeah, next time I do a repair, I'm going to write a clearer tutorial, with pictures, and post it.

 

[wiltw]

Back in the 1990s I had purchased a used film magazine, which caused intermittent misfire with my new (not purchased used) ETRSi body. The film-advanced interlock pin in the magazine protruded too far into the body. As a result, the mirror would swing upward, but it was prevented from swinging up fully all the time. As a result, the lens would sometimes be prevented from actuating the shutter and the flashing red LED in the viewfinder would not indicate shutter fire. If I mounted one of the film magazines which I had purchased new, there was not a problem...it happened only with the one used magazine, and intermittently. I needed to send both body and back to Bronica repair facility, where they shortened the pin on the magazine so it would not cause the mirror to make incomplete upward motion.

 

[JohnRichard]

So now with the lube I've got it working 40% of the time. I guess I need more lube or different lube.

 

[JohnRichard]

After days of cleaning and re-lubing, letting it set in. Running it through all speeds at all lengths I find that at infinity, it works. Focusing in past the 5 foot mark it starts to hang, and anything past 4 will not fire unless "helped".

This lens is basically unusable to me. However, I wonder if the springs in the body that cause the rotational force are just weak from use. Because of the design of the lens, racking it out would cause force to fall off exponentially,
if I remember my physics. Anyone else want to chime in?

I now need to figure out if it's worth a full CLA, body and lens - or do I need to sell it and seek out a new camera. To tell the truth, I don't think I would mind selling it if I could find a decent back for my Speed Graphic (that wasn't $600!). Decisions, decisions...

 

[lxdude]

Force should not fall off at all, because the actuation arms which extend into the lens and transfer the motion from the body to the cam plate, move in a fixed arc, regardless of what point along those arms the cam plate makes contact with them.

A few things to consider: The body does not generate much force on release. The pins must have only a little resistance to being moved at the start of their travel. Cocking the lens requires some force, which provides the spring tension to work the shutter and diaphragm, but once cocked, the pins can be moved in the release direction easily.

Check manually that the pins move easily in the release direction (clockwise, looking at the back of the lens). To release, move in the lock tab located on the lens, inside the mount ring between 4 and 5 o'clock as you look at the back of the lens. The pins will have a slight resistance initially, then move very easily until they reach a detent near the end of their arc.

Check that the rotating piece which is attached to the back plate, and has the pins and actuation arms on it, can move completely freely through its entire travel.
Check that you put those actuation arms into the proper slots in the cam plate (the plate which moves the rollers as it it is turned).
Check that you used the right grease. A light grease which is not sticky should be used, as a thick and/or sticky grease will create resistance to motion.
Check if anything seems to be misaligned and feel if anything seems to be binding.

The critical point is where the rollers contact the cam plate. That is where a lot of localized force is generated, and all the old grease must be gone. The cam plate must move easily in the release direction, and the rollers must follow.