RB67 film back (Pro S) malfunction?

Ariston · Sep 20, 2019

I rarely change film backs, though my kit came with two, way back when I bought it. Well, I just used "the other" film back, and it would not advance after shots unless I used that lever that is intended for the press cameras (I think).

Does anyone know what may be the problem? There is a good chance that it is user error, which is what I'm hoping.

MattKing · Sep 20, 2019

Is there any chance that your "other" back is actually a "Pro" back, and not a "Pro S" back?
If so, that other back is working normally.

Ariston · Sep 20, 2019

MattKing said:
Is there any chance that your "other" back is actually a "Pro" back, and not a "Pro S" back?
If so, that other back is working normally.

No, it says Pro S on the back. It's not a big deal to trip that lever each time now that I know, but I did screw up an exposure because of it. I am just curious why it is doing that.

MattKing · Sep 20, 2019

Does the insert also say Pro S?
Technically, the outer shell and inner workings are separate and you can switch them out.
I have never seen anyone actually do that, but it is possible.

Ariston · Sep 20, 2019

MattKing said:
Does the insert also say Pro S?
Technically, the outer shell and inner workings are separate and you can switch them out.
I have never seen anyone actually do that, but it is possible.

I'll check.

Ariston · Sep 21, 2019

Yes, it is Pro S. I saw an old post on another forum where someone had a similar problem, but there was never a solution. My backs operate smoothly and look good. Oh well. I've marked it so I know.

MattKing · Sep 21, 2019

Most likely than you have an interlock connection that needs servicing. There are spring loaded pins that allow the body and the back to communicate, and they sometimes either get bent or need to be cleaned and lubricated.

shutterfinger · Sep 21, 2019

Download the service manual at: https://www.manualslib.com/manual/1015573/Mamiya-Rb-67-Pro-S.html
The roll film holder begins on pdf page 48.

Ariston · Oct 3, 2019

shutterfinger said:
Download the service manual at: https://www.manualslib.com/manual/1015573/Mamiya-Rb-67-Pro-S.html
The roll film holder begins on pdf page 48.

Thanks, Shutterfinger. I looked at the service manual you posted, and I am not confident enough to take the back apart. It will probably cost as much as the back is worth to get it serviced, so I will just have to train myself to hit the release lever. My other back works properly, so I will stick with it most of the time.

Ariston · Oct 5, 2019

I need help. I will start a thread if no one sees this older thread.

I tried to use my “working” film back today, and it doesn’t advance, either. That made me paranoid, so I looked at the lens for my next shot, and the shutter was not firing.

I got back home and looked at the camera. The mirror will cock, and fire, but the rear flap does not come up. It is also not firing the shutter in either lens. I can see the ring on the lens mount of the body cocking, and it appears to cock and fire correctly, though I’m no tech. If I cock and fire the lenses manually (not mounted), they both fire correctly, too.

Am I missing something simple, or do I need to send it in? When mounted, everything acts like it is working except the wind. I can cock it and fire it. But really, the shutter isn’t firing, and then I cannot advance the film without pushing that little tab.

The dark slide is out. I’m hoping there is a simple fix someone can help me with.

MattKing · Oct 5, 2019

Check that the Mirror Up setting on the lens isn't partially or fully engaged.
But otherwise, it sounds like the interlocks.

RB67 film back (Pro S) malfunction?

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