Mamiya RB67 Pro S Back - Repairs Manauls

GuyBoden

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One of my backs is playing up. The counter is stuck on a number and doesn't reset when opened. I could count the wind-ons to frame one (and beyond) I guess but would prefer to fix it. Also the winder stick at some point with every film giving either blank or double exposed sections on each film.

The cost of repair will outweight the cost a new (secondhand) back so I'm game to give it a go to fix it myself. Does anyone know where i can get a repair manual or layout diagram for the Pro-S backs before I attempt to pull it apart? I've searched high and low!

Many thanks,

Guy
 

CGW

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Have never seen an online repair guide for RB backs apart from DIY light seal instructions. You could fish around for just a 120 Pro S 120 insert. Failing that, a used 120 Pro S back might be the easiest solution since they're not uncommon on the used market. I'm guessing yours is probably just worn out based on the busted counter and advance issues.
 

picker77

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Sorry for the late reply. One of my three Pro-S backs did the same thing recently, and for the same reasons as you I decided it was not worth it to send it in for repair. So, out with the camera repair tool box and let's see if I can fix this thing. It CAN'T be all THAT complicated, just a film counter and advance ratchet.

Not so fast, my friend. My eyes got big when I took the cover off. That thing looked like a Swiss watch inside. Fortunately, mine had an obvious problem: the main cast metal piece the advance lever and return spring drop into had one of it's two large "arms" broken off. Easy fix with JB weld. Reassembled and tested, but although the film counter and advance now work (for three or four frames, at least) the back jammed after that. I haven't had the moxie to take it apart again, but trust me, that is NOT a simple mechanical assembly in there. I know my limits and I'm not Jimmy Koh, so guess I'll fumble along with my remaining two backs but start looking for a replacement! I also have wished for a repair manual for the backs, but not sure that animal exists.
 

benjiboy

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It's one thing to have the service manual, and another to be able to repair it.
 

CGW

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Unless you get lucky with a repair manual(and don't need parts), I'd just shop for a new back. You might get lucky and find just the 120 insert. A Pro back is another option but these are even older. NOS Pro S 120 backs show up occasionally on the big auction site.
 

23mjm

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I had a back that kicked the bucket--so I tore into it--it would make a Swiss watchmaker proud!!! They are just a tad more complicated than one would think! But other than lightseals it is just not worth repairing---eBay and KEH are the place to go, but I have noticed the prices are climbing up slightly. Don't know if the supply is shrinking, or if the demand is going up.
 

CGW

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Seals, I do; the rest is like amateur dentistry, i.e., not smart. Price movements are puzzling. I got some NOS boxed KL lenses, Pro S backs and a Pro S body kit in spring 09 for peanuts--I mean cheap. While there is a bunch of nearly dead Pro kits and Pro S bodies+backs+finders, clean low mileage stuff does seem to be getting pricier--more from shortage than rampant demand. I'm surprised what friends have paid recently for RB67 kits in very rough shape--dumb or desperate isn't certain but rational people do make odd decisions after the MF bug bites.
 

hpulley

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Just got some seals from Japan to redo one of my Pro-S backs which seemed to give me a light leak and certainly looks quite awful for foam though mechanically it is sound. Alcohol to remove the old foam is best?
 

CGW

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hpulley said:
Just got some seals from Japan to redo one of my Pro-S backs which seemed to give me a light leak and certainly looks quite awful for foam though mechanically it is sound. Alcohol to remove the old foam is best?
Click to expand...

Dude, you should have asked me first. I use thin adhesive back sheet foam from Michael's--like a buck for an 8x10 sheet...

Get a popsicle stick or any other small piece of wood and cut it into chisel shape. Make several. Use a QTip with some isopropyl to moisten the old foam. Carefully scrape it out--as much as you can. Let it dry and go back for more--remember you're removing both foam and adhesive. If you need an online anatomical photo of the RB back, I'll send a link. The really critical seals are at the hinge and clasp of the outer shell and the RB adapter surface that meets the back. The foam in that square channel surrounding the film gate is a critical light baffle. Let me know if you need any help.
 

hpulley

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This stuff is pre-cut for $16 shipped from Nagoya (will have to say hi to him next time I'm there). How do you but the stuff to the right size and shape?

Thanks for the offer of help, I might need it...
 

CGW

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hpulley said:
This stuff is pre-cut for $16 shipped from Nagoya (will have to say hi to him next time I'm there). How do you but the stuff to the right size and shape?

Thanks for the offer of help, I might need it...
Click to expand...

Xacto knife and a steel straight edge. Have used this adhesive-backed foam and felt for years for 35mm clunkers. Works perfectly. Maybe I'm more of a survivalist than I think...Enjoy the holidays.
 

picker77

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paul ron

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It is very easy to open. There are 2 screws one at each corner on the top, two more on the underside by the spool. Once those are out, take off the dot of leatherete on the lever and unscrew the large center screw. The lever should pick up but be carefull to not lift the winder or you will lose the spring tension. No problem putting it back as you will figire it out sooner or later that it catches the matal plate that sits on the spindle.

Whe taking the top off, watch for the little slip of metal that covers the hole on the lever side. That has to slip into the slot, just as you will need to do when reassembling it. I put the insert in multi froame more so it will retract the slip of metal, it makes it easier to remove the over.


Your problem soounds like the small lever that hits the edge of the shell is not engaging properly. That will be on the counter side near the top.

Put the insert with the lever reinstalled into the shell loaded with a test roll of film, just the paper backing is enough and try cocking n firing it to see how everything works together.

BTW while it is open install new seals before reassembly, it makes it so much easier to do.
 

epatsellis

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I have found that velvet ribbon works best on the hinge side of the outer shell personally. While I have no problem using the foam from Michael's or Hobby Lobby, it's frequently too dense.
 

CGW

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epatsellis said:
I have found that velvet ribbon works best on the hinge side of the outer shell personally. While I have no problem using the foam from Michael's or Hobby Lobby, it's frequently too dense.
Click to expand...

That's not been my experience. Michael's in Canada sell an ultra thin adhesive backed foam that works perfectly. Their usual is about 3mm--too thick even when compressed.
 

epatsellis

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CGW said:
That's not been my experience. Michael's in Canada sell an ultra thin adhesive backed foam that works perfectly. Their usual is about 3mm--too thick even when compressed.
Click to expand...
That would probably work well, I haven't been able to find such an item locally, and I have plenty of velvet on hand.
 

Ric Trexell

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I just used felt from Wal-Mart.

When I got my Rb I read about the seals being bad on those cameras. They mentioned foam and felt. I dug out the old foam and went down to Wal-mart and bought some felt. I comes in a 12 in. X 12 in. square or there abouts. I cut it with a hair cutting scissors and glued it in with rubber cement. It has worked great and I haven't seen any light leaks. I repaired another one that way but haven't tried it out yet. If the door doesn't close, I just pulled out some and replaced it until it did. You can buy those expensive foams seals but they will eventually turn to gum where as the felt won't. I haven't heard any reason not to use it, so if it isn't a good idea, stay with the foam. Ric.
 

CGW

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I've used a thin adhesive-backed felt, too. It's worked well on some 35mm SLR backs. I think the foam kits are over-priced and often overkill.
 
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