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     Aphototaker Tinkerer Username: Aphototaker Post Number: 265 Registered: 12-2009 Rating: N/A |
I had mentioned in an earlier thread (URL: https://kyp.hauslendale.com/classics/forum/messages/2/19832.html?1284003941) that I wanted to open up the mirror cage of my Canon A-1 to clean and lubricate it (the diaphragm was not closing to its minimun value of 16 on my lens, it would top at around f/9.5 or f/11). User brcamera was kind enough to comment on the problem. So here is what I tried: 1. After looking at various diagrams of the side of the mirror box which has the diaphragm setting lever, I used a syringe to lubricate the gears. Did not work, the diaphragm setting lever was still moving and making sounds like dry gears. 2. I decided to open up the mirror cage and tackle the problem head on. This is where things got a bit interesting, as described below. To open up the mirror cage, I removed the leatherette using naphtha (to dissolve the adhesive). After removing the leather covering, I tried the diaphragm again and lo and behold, it was working without any previous noises! Looks like some naphtha made its way to the gears and did some cleaning and temporary lubing there. What is interesting here is that I tried my lens and noticed that this time, the diaphragm seemed to be closing a couple of stops more than what was shown in the meter (VF display). So the problem has somewhat reversed. Previously, the lens was not closing to its minimum aperture, and now it was closing two stop more than required, and quite consistently. And this was without opening the mirror box yet! Even though the diaphragm was moving like well lubricated arm, I knew that naphtha's effect would wear out eventually and the problem would resurface. So I continued to dismantle the mirror box. Desoldered the necessary wires*, remove the screws, etc. and got the box out. Lubed all the relevant parts and put the box back in**. The problem still remains though: the aperture diaphragm closes about two stops more than what is shown by the meter. Does somebody have any idea how to debug this problem? Thanks. * The wires to be desoldered are different (in color as well as in number) that what is shown in the service manual that I have. * Cleaning the mirror was a breeze with the mirror box out! It was quite satisfying to do this  |