RB shutter button sticking

Wayne · Feb 23, 2012

MyRB67 Pro shutter button is sticking a bit. I've turned and unturned the knurled washer a couple times, and it still sticks unpredictably with both my lenses. Whats up? I've checked all the safeties and I think they are OK. I can never be sure if its going to trip when I want it to. Sometimes it goes if I push it a little harder with my finger, and sometimes it doesn't. With a shutter release (which I always use when taking pics), I won't even try to push it harder if it sticks.

paul ron · Feb 23, 2012

Take the bottom plate off, 4 screws, see if anything in there is bent or hanging or needs a light smear of grease?

See if the pins in the 2 chrome tits on the rev back are moving freely? Is the rev back locking in place properly?

One more thing.. be sure the palm of your hand is not pressing on the small metal tab of the rev back, bottom right side, as you fire the camera, that is the "back on lock" n dark slide sensor.

If not then the side pannel (opp the lever) needs to come off n a good CLA is in order.

.

Wayne · Feb 23, 2012

I've been testing it with the back off. I discovered by accident it works fine if turned 90 to 180 degrees left (on its left side to upside down), but it often doesn't work properly upright or rotated onto its right side. Maybe that's enough for someone to diagnose it before I open it up...

paul ron · Feb 23, 2012

Wayne, How long have you been using an RB?

Be mindfull of where your hand is when firing it? There are 2 little tabs on the right side of the rev back that goes in n out with the graphloc slides that lock the back on. If you are pressing one of em, the camera will act intermitanlty as if it won't fire and only in certain positions.. just so happens to be the positions you can't toutch the tabs.. to the left. It is a common problem.. more a design flaw of the RB.

THEN... Take the bottom off... just 4 screws, nothing will pop out, I promise... n see what it is doing as you fire it. It can just be a simple bent tab.

Wayne · Feb 23, 2012

I've been using an RB for about 8-10 rolls now-not very long. But I'm not touching those RB tabs, I've held it from the bottom or had it sitting on a table. But I rotated the back to vertical and it suddenly stopped having button troubles, and its still working now that I rotated it back to horizontal. Love my RB but its a complicated little beast.

Messing with those RB tabs a bit now, I notice that holding the bottom one (when the back is horizontal) will cause the exact same problem I was having. But the top one does not affect the shutter button though. Maybe something in those tab mechanisms was sticking/malfunctioning?

paul ron · Feb 24, 2012

Great we are getting somewhere now. You've proven the problem is with the rev back. The bottom tab is the one that will lock the fire button n many people tend to hit it with the palm of their hand while readying for a shot. That tab is your problem, may just need a bit of lube on it.

Now that you say rotating the back makes a difference the problem maybe the rev back needs to be cleaned or just a simple dab of lube in the right places can cure it.

Take the rev back off n see how she fires? Problem gone now?

If you rotate the rev back while off camera you will figure out just how she works.

e-mail me?

bushpig · Feb 24, 2012

Sweet corn, Wayne.

I've been silently following your progress with the Mamiya (I think I probably posted a few times in the thread where you were debating on getting one and finally did).

I'm SO sorry you're having these problems. I really hope you get it all worked out very soon. You're such a trooper.

Good luck with your RB. I promise, they're AMAZING if they're working right. You might end up just having to send it to someone for a CLA. Let them figure it all out. Wouldn't actually be a bad idea.

Wayne · Feb 24, 2012

I see the problem now, and how that mechanism works. That lower tab engages with one corner when vertical and the other corner when horizontal. The corner that gets engaged when vertical moves much more freely, so the shutter works fine when vertical. So I need to clean and/or lube the other one, which obviously has stickier action and does not move as freely.

Unfortunately I need a small screwdriver that I don't have. What should I lube it with when I get the little corner access panel off?

RB shutter button sticking

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