I did a tear down, and cleaning, to fix a few issues of a Canon Demi S this past weekend. It was a really disgusting piece covered in dust, mold, dirt, and in some areas even salt deposits?! The mold had even eaten into the metal on some parts. I remember when I had opened the back the first time when i got it, there was a small plume of mold/dust that kicked up, and I started to sneeze lol. The leatherette case it was in, was caked with it.
I would never have bought this camera had I know about this, but the guy who I bought it from failed to mention this(as well as a few other things), and ultimately didn't even want it back since it sold for so low. So it sat in a corner for awhile, debating if I should even work on it, or just toss it as a lost cause.
The shutter, aperture, and wind, were all stuck, basically all seized up. When I started to take it apart, I noticed that the camera had been worked on before, there was one screw that was stripped, and the others had tool marks on them. The leatherette covering also had holes in it, that exposed the screws, which were painted black, I assume to cover up previous work?
Well I wiped all visible and reachable surfaces with a lysol disinfecting wipe(except the lens), while using a screwdriver to poke the wipe into the smaller areas. Flooded the fungus/mold ridden foam on the back with naphtha and scraped most of it away.
I first took off the front panels, to try and check for the wind jam but couldnt find it. tried firing the shutter by manually pressing down the lever on the side of the shutter assembly, but it didnt work. The I unscrewed the front lens assembly/ shutter speed/ aperture ring/Asa ISO spring dial to try and get deeper. Still coudnt fix it, So I thought it must be stuck in the gearing under the wind lever. So I took apart the top plate, and traced the problem back. It was a gear catch lever that wasn't returning, which blocked the wind lever from moving, if you hold it open with one hand it allowed it to wind. so I retraced the connections and I applied a bit more force to return the long connecting lever from the wind to the shutter assembly and it popped back into place. This fixed the winding problem.
Now onto the lens, since It wound up, I tried to fire it, but nothing happened and the aperture was still stuck open. I soaked a Qtip in naphtha and touched on the sides of the shutter, and after a bit, it popped back as well, and the aperture blades were able to open and close up. But after drying the problem returned.
I did this a number of times, flushing it with a soaked qtip, and firing away at all speeds. It was quite frustrating. This part took the longest. I ended up realizing from reading a bit more online, that I probably needed graphite to lube the blades. I didnt have the option of running to the store, not even sure where and if its even sold by me. So I took a piece of mechanical pencil lead (which is graphite as well) and scrapped it with the sides of a sharp pair of tweezers, which gave me a fair amount of very fine material to work with.
I applied to this a small bit of pec-pad, and rubbed it on the still wet shutter. I alternated this and firing, and finally drying it out with compressed air. and then finally it worked and stayed working.
Reassebly wasnt that tricky, but I found out that If you tighten the screws on the lens assembly a bit to much, you lock the shutter speeds and the aperture settings from turning. I had to take it apart and loosen then screws a bit and assemble again.
So mission accomplished, I have to put some foam in the back if I have time this week, and Ill shoot a test roll and see how it performs. =]
