11 Sep 2014

Mamiya C33 TLR Repair - Part 1



A short while ago I acquired the Mamiya C33 pictured above with a Sekor 80mm f2.8 lens and a porrofinder. Both the body and the lens needed some TLC so I will show you how the process went in this blog post.

Both the advance arm and the release were stuck with no movement whatsoever. The lens shutter was working but the aperture arm was stuck firm in place and would not budge.

I will break the entire process into three posts. In this one I will talk about the body and show the pictures that I have taken of the inside of the camera. Then in the following post I will talk about the focusing screen, and finally a third separate post will show how to get the aperture working in the lens.

1. Body repair:
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Since the problem seemed mechanical, I first needed to reach the gear. The mechanism is housed on the right side of the camera body where the advance arm is. To remove the cover you need to remove eight screws: six that hold the cover in place, and two that hold the advance arm in place, and unfortunately, to remove them, you need to lift the leather finish.

You can lift the faux leather finish by heating it up slightly with an air dryer if you're worried about tearing it apart to soften the glue that holds it in place. In my case I could just pull it very carefully with some fine tools and lots of care to avoid any tears. You can see in the picture below that the glue was anything but fresh so it didn't have the amazing grip prowess that I would need an air dryer to counter.


Just pull enough to expose the six screws, about 1cm from the edges. Try your best not to strip them as they are in fact very soft metal, so only use the right size of high quality screw driver. Also, these are not iron, so a magnetic screwdriver is of no use. Have some fine tweezers handy.

Also make sure you keep the screws in order and remember where each one goes because they are different sizes. In the following picture you see the six screws arranged nicely on the left-hand side. The two screws in the middle hold the advance arm. The other bits in the middle also belong in the arm section. Ignore the light meter on the right hand side as it comes from a Petri 7S repair project.


The metal tube thing just under the light meter goes with the longest screw. Do not lose it.

Nicely remove the arm and the ring that holds it in place, then lift up the cover. I apologise for not taking picture of this part of the process.


Here is a picture of the gear section. The big gear with numbers is the frame counter. It is operated by the big yellow ring next to it, which is in turn operated by the small gear under it. Now this small gear is actually turned from the other side of the camera where the take-up spool actually plays the role of a cam that shifts the movement from this side to the other, and then back here to this small gear.

When the back door is closed, the big yellow gear is pushed in and engages the gear hidden under the counter gear. This hidden mechanism does two things: it advances the frame by one until it locks, and released the lock on the release lever. When the release lever is depressed, the lock engages on it, and releases the advance gear again. Very simple.

A bit of the right kind of lubricating oil solves lots of problems on these old and durable cameras, so let's put everything back in place and move on with our repair project. Make sure you fit the little metal tube thing in place for the long screw on the lower left-hand corner of the image above.

Here is an explanation of what everything is and how the mechanism is designed to operate.


3 comments:

  1. Hi, I have just bought a C33 and I'm waiting for it to arrive. Your articles should prove to be very useful though I was wondering what had happened to the photos.

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    1. Hi Steve, and congratulations on your purchase. It seems that all photos on my blog are currently down, and I suspect this has to do with a Google-Phone sync issue. I've deleted files on my phone to clear space and suddenly, my blog was image-less. I am working on restoring all photos now, but this may take a short while. I apologize for this, so please follow the blog, and you will see the photos returned as soon as I can.

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    2. Thanks Noah, my camera arrived and it has a shutter problem so hopefully I can fix it.

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