broken 7s frame counter

[stet]

Does anyone know if it's relatively easy to repair the frame counter on a Canon 7s? This weekend it went funny on me. I finished shooting a roll, and when I reloaded and closed the back, it didn't reset. It then advanced properly, and I was able to shoot and have the counter keep going up. Then it stuck on 40, the top end of the counter. I hope it wasn't bad to shoot past that, because I had come upon a scene I couldn't stop shooting, and I finished that roll there, maybe 30 shots stuck on 40. (The film andvanced properly and devved fine, if that lends any more information). After that roll was done, I rewound and opened/closed the back a bunch of times, but it's still stuck on 40.

Anyone ever deal with this problem before? It had a CLA about a year ago. When it came back the funny eyeball thing would still roll around after a roll was rewound, but I never sent it back because I was starting a photo class and couldn't lose another month to shipping and repairs.

Rick

 

[VictorM.]

I can't believe no one has answered yet...first contact the person who did the cla. They should advise on the frame counter issue. If you think you can look at it yourself, check the repair instructions: http://www.kyphoto.com/classics/repairmanuals.html.

 

[jlw]

Am I summarizing correctly to say that the counter counted correctly until it got to 40 (where it stopped simply because that's as high as it goes) and the problem is simply that it doesn't reset when you open the back?

If so, it's probably not a serious problem, but getting at the frame counter mechanism requires that the top cover come off. That's not a hugely difficult job on a 7s -- but it's one you probably shouldn't tackle unless you have a good "touch," the right tools (including a pin wrench) and a bit of experience, because there's a risk of gouging the camera's finish when you remove the sync plug and wind-lever retaining disc, and it's fairly easy to screw up the ISO-setting mechanism under the shutter speed dial unless you know what you're doing.

Before you send it off for a fix, though, one thing you could check: open the back and look at the upper right edge of the film loading opening. There's a little rectangular hole there, which is where the counter-reset catch is pressed in when the camera back is closed. The idea is that when the back is opened, this catch moves outward under spring pressure, unlocking the counter and allowing it to reset. Once in a while, a little chip of film can get caught in there and keep the counter from resetting; if that's the only problem, you may be able to fish out the chip with tweezers and go on your merry way.

As for continuing to use it with the counter stuck at 40, I don't think this will hurt it, so if you've got an important shooting opportunity coming up soon and don't want to be without your 7s, I'd say go ahead and use it.

 

[stet]

thanks for the replies. I was hoping it would have something to do with that catch in the upper right corner of the back, because I'm not that dextrous to remove the top and fiddle around. I'll leave that to technicians.

What worries me, though, is that I don't see a rectangular hole up there; I see a little metal latch sticking up, past the black part of the camera back with its tip extending to just below the camera top. Does that mean something has gone horribly wrong? 🙁

As for the CLA, I was living in the US when I had it done I won't be back there till next year, and probably not long enough to have it redone and sent back to me. I've been to one store in Bangkok that that might be a good lead on Canon RF repairs, but I'm not getting my hopes up too high.

On the bright side of things, this situation will help me be sure to bring more film than I need, and hopefully to finish a roll soon after I start it.

 

[jlw]

What worries me, though, is that I don't see a rectangular hole up there; I see a little metal latch sticking up, past the black part of the camera back with its tip extending to just below the camera top. Does that mean something has gone horribly wrong? 🙁

It doesn't sound as if anything much is wrong. I may have been misleading when I described a "hole" -- there's a hole, all right, but it's very small, it's black (being a hole) and it's hard to see because it's surrounded by the black light-trap groove.

Without a REALLY strong light, all you can see is the tiny silver end of the catch lever. I just looked at mine, and it sounds about like what you've described: it sticks out just past the edge of the black main casting, but not far enough to protrude past the edge of the chrome top cover.

You might try pressing GENTLY on this catch with a tiny instrument such as the end of a toothpick, to see if it moves freely, but that probably won't tell you much.

Very brief description of how a generic counter mechanism works, to help you visualize wha't inside:

-- The counter consists of a numbered disc with ratchet teeth on it.The disc is connected to a spring that winds up as it turns.

-- A ratchet pawl engages these teeth, allowing the disc to turn in only one direction (counting upward.)

-- Each time you stroke the film-advance lever, another pawl connected to the film-advance mechanism advances the disc by one tooth. As the disc advances, it winds up the spring a bit more. The spring can't unwind because the ratchet pawl is holding back the disc.

-- The ratchet pawl also has a tail on it, which is what you see when you peer into the upper right corner of the light trap. When you open the camera back, this tail is able to spring out a bit. That action lets the pawl move away from the teeth. When that happens, the spring can unwind, causing the disc to rotate back to the starting position. When you close the back, the tail again presses the ratchet pawl against the teeth of the disc.

As you can see, not much to it. My guess is that your counter doesn't return either because there's a bit of debris jamming the ratchet pawl, or because the disc's spring has come loose. Either should be a simple fix for a technician once the mechanism is in view.

 

[stet]

thanks again for the descriptions, and for teaching me a new word. I had to go to the dictionary and Google Image to understand what a pawl is, and simple as it sounds, I'm going to wait until I can get a technician to do it. I'll probably print out your post and the repair manual page to help explain things, if need be. I just hope that the Leica repair shop in Bangkok can do this; I don't think I'll have much luck finding a Canon RF specialist in Thailand.

OT, I love this forum. Such a great resource and community.

*rick