Canon FTb Frame Counter

[KoNickon]

I just got a decent FTb for a good price. Unfortunately, the frame counter isn't working right. When I got it, the counter was stuck at the final frame (38). I removed the top and as I was shimmying it off, I heard the counter reset of its own accord. I proceeded to reinstall the cover and tested it -- worked fine: counter advanced and reset properly. But evidently I didn't wind it far enough, since I tested it again after winding to frame 26 (i.e. the end of a standard roll) and it did not reset.

So what's the problem here? I admit that I didn't study the mechanism to check for dirt or grime since I figured that whatever the problem was had sorted itself out. And I would have supposed that, the higher the frame count, the higher the spring tension and thus the more likely it would reset when the back was opened. Seems counterintuitive.

Has anyone worked on this or a similar mechanism? Is it possible that the top cover itself is binding the mechanism in some way? I see no evidence of deformation in the top cover stamping.

 

[Mackinaw]

I had the same problem with an old Canon FP I have (same chassis as the FTb). This is from memory, but mine was stuck at frame #4, or something, and wouldn’t move, I took off the top plate and fiddled with the mechanism. There’s the “counting” arm that pivots against a spring which supplies the tension to move the arm. The arm didn’t move freely. It turns out that the entire frame counting mechanism was over-tightened (don’t ask me how this happened) which “warped” the mechanism. I believe three screws hold the mechanism in place. As I backed off the tension on a few screws, the counter loosened up and now works OK.

It’s harder to explain than to fix. Once you take off the top plate and look around, what I said will kind of make sense.

Jim B.

 

[mikemc_photo]

Basic counter...see if the counter window is missing from the top cover, they fall down and cause erratic binding...If you find it, it will be gouged..not available for years though

 

[KoNickon]

Thanks, the window is in its proper place.

 

[KoNickon]

I thought I would have another go at it last night, but things took an unpredictable and bad turn. In reassembling the camera, I must have screwed the rewind crank in too tightly, because when I went to remove it by the standard trick of inserting a screwdriver into the fork end in the film compartment, the fork end, not the crank, would unscrew. Never had this problem before; the FTb appears to have a different design such that the fork end can be loosened rather easily. (And the fork does not tighten all the way down into the spindle, for some reason; there is a small amount of play built in.)

Being unable to budge the rewind crank, I figured I'd just remove the fork end and draw the crank and spindle out in one piece, and then reinsert it and reattach the fork once the top cover was off. The fork end must be attached to the spindle in order to open the back (and thus test the frame counter's resetting when the back is opened).

Here began the fun. I drew out the spindle and out of the shaft dropped a minute (1.5mm at most) ball bearing. Immediately I realized that this was what kept the shaft in its detent positions and from freely moving up and down in the shaft. It had not occurred to me there might be a ball bearing in there. But where the heck it was supposed to go, and how to reinsert it, seemed like a major hassle.

After a bit, with the use of a flashlight, I saw what appeared to be a small recess in the shaft wall, toward the top. With a toothpick I probed it to confirm that was what it was. I reinserted the spindle, minus the crank (which I'd managed to remove using pliers and a piece of rubber protecting the shaft from the pliers' teeth), partway up the shaft to a point just below where the ball recess was. I figured the spindle would keep the ball from dropping down the shaft.

I then dropped the ball into the shaft, and with the toothpick coaxed the ball to the recess. I then applied careful pressure to push the ball further into the recess, while pushing up steadily on the shaft to slip it past the ball. It went without too big an effort. (I had images of the ball suddenly springing free and flying up out of the shaft to God knows where.)

I was then able to reattach the crank -- lightly snug only this time! -- and close the camera up for another go at the main problem. But that won't be for a few days.

So here's a classic example of a seemingly routine aspect of camera tinkering can veer off unexpectedly into an extra and unpleasant task. At least I did no harm. Thanks for reading.

 

[Steve M.]

It sounds as if the counter is working but not resetting? Did you ck that little tab on the back of the camera that resets it? It's on the body in the light seal channel on the top right when you open the back door. Sometimes it gets bent or just hangs up. The link below has some good tips for anyone taking the top off theirs so that the shutter speed dial/meter calibration does not get off when you take the top off. Great cameras! Sorta the Leicaflex of Canon FD mount cameras, but made much simpler than the Leica. I had to buy several of these cameras before I got a good one, but several FTb's are small money. Let me know if you need any parts, and I'll send you a parts cameras for just the price of the shipping.

http://www.rangefinderforum.com/classics/forum/messages/13061/8469.html?1168658480

 

[KoNickon]

Thanks, Steve, the tab is there and works fine -- plenty of spring tension. As mentioned, it seems the counter will not reset only when the frame counter gets up over 20 or so -- works fine otherwise. That's what's so odd about this.

I appreciate your offer of a parts camera. Hopefully it won't come to that!

 

[mikemc_photo]

So if everything is clean and clear, you should be able to add 1 turn of tension, If I remember you need to slide the clip off the dial and lift up a hair to add tension past the stop. Split R/w forks are expensive so they went bye bye, I have a hooked tool that allows me to lift the latch, with or without the shaft in place.If you have a pair of parallel jaw pliers, and a bit of inner tube you can hold the shaft while unscrewing the knob

 

[KoNickon]

So if everything is clean and clear, you should be able to add 1 turn of tension, If I remember you need to slide the clip off the dial and lift up a hair to add tension past the stop.

Thanks -- I guess I'll have to get in there and see what you mean. Again, I would have figured that if the counter is tensioned by a spring, then the more it's turned (i.e. the higher the frame count), the more likely it would be to return. Seems counterintuitive!

 

[mikemc_photo]

So if everything is clean and clear, you should be able to add 1 turn of tension, If I remember you need to slide the clip off the dial and lift up a hair to add tension past the stop.

Thanks -- I guess I'll have to get in there and see what you mean. Again, I would have figured that if the counter is tensioned by a spring, then the more it's turned (i.e. the higher the frame count), the more likely it would be to return. Seems counterintuitive!

The more its wound,(higher) the more the spring is tensioned...Most counters have a turn of tension applied

 

[KoNickon]

I think I have fixed it. I opened the camera up again last night, and after trying a number of possibilities, I believe I found the cause.

After removing the advance crank and all the washers of various types below it, you reveal the hole in the top deck that allows the wind mechanism to connect to the wind crank. The film counter disk is visible right below the hole in the top deck. The disk is attached to the rest of the film counter mechanism by three screws, and those screws are accessible by small circular cutouts on the perimeter of the main hole in the top deck.

Apparently the edges of the main hole, between the smaller cutouts for the screws, had gotten bent downward, enough so that the screws were catching on those edges and thus not allowing the disk to reset when the back was opened. I carefully bent them upwards and the screws now seem to be unobstructed by the top deck.

 

[mikemc_photo]

Simple as always!!

 

[KoNickon]

So simple that it took me quite a while to figure out....