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Aphototaker
Tinkerer
Username: Aphototaker
Post Number: 259
Registered: 12-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, September 08, 2010 - 12:05 pm: | 
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It appears that the gears moved by the diaphragm setting lever need lubrication in my Canon A-1. When I move the lever up and down, I can hear the whirring noise, which indicates dry gears moving. That same lever does not make that kind of noises in my other fd camera.
Looks like I need to remove the mirror cage to do this. Before I peel away the leatherette and open the screws from the front, I wanted to know if I need to do any desoldering at the top (wires or flex circuit). Can somebody give any hints to keep in mind while doing this?
Thanks. |
Brcamera
Tinkerer
Username: Brcamera
Post Number: 27
Registered: 08-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, September 08, 2010 - 04:34 pm: |
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Although I can't get into all the details of what wires to de-solder, there are quite a few, including the LED's which remain with the mirror box. It takes a light touch to remove the LED's and the other wires so be very careful as you can fry the flexible circuit board easily. I am not sure why your diaphragm setting lever is moving at all as it stays in the locked position at all times except during the time of exposure, so maybe there is some issue there? |
Aphototaker
Tinkerer
Username: Aphototaker
Post Number: 260
Registered: 12-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, September 08, 2010 - 05:01 pm: |
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You are correct regarding the dia. setting lever. But I was trying to verify its functioning by cocking the shutter and activating the DOF switch. In this situation, the dia. setting lever can be moved towards the bottom. When freed, it goes back up under its spring tension. This how I realized that its gears seem dry ... they make a sound not very different from the made by a dry mirror flywheel (the canon shutter squeak or squeal).
I am going over its service manual in which there are a couple of pages which show which wires to desolder. But the manual is a bit cryptic, and the numbers shown do not have an accompanying diagram showing that part.
Removing the mirror cage is going to be my last resort. If I can lubricate the gears somehow using a syringe, that would be the easiest |
Brcamera
Tinkerer
Username: Brcamera
Post Number: 28
Registered: 08-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, September 08, 2010 - 05:18 pm: |
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Well, most all the A-1's that I see these days have a bit of a squeak on the diaphragm rachet gears. I haven't seen it cause any problem yet, but I realize that the squeak may be annoying. It's just that the mirror box on the A-1 is not that joyful to remove! As you mentioned, a surgical strike with a syringe might solve the problem but there is also risk of getting oil on the diaphragm sensing resistor that lives just next to the gear train and that would not cause happiness. Good luck! |
Aphototaker
Tinkerer
Username: Aphototaker
Post Number: 261
Registered: 12-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, September 08, 2010 - 05:58 pm: |
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Yup, that resistor was my major concern. That is why I am still studying the problem to decide which would be best way forward.
Isn't this diaphragm gears' squeak also referred to as the winding squeak? Looks like the diaphragm setting lever is reset when the frame is wound, and that resetting moves the gears and thus the squeak during winding ... if I am correct.
The other attraction of removing the mirror box is that the prism can be cleaned as well. But that comes only if I have to remove the cage. |
Brcamera
Tinkerer
Username: Brcamera
Post Number: 29
Registered: 08-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, September 08, 2010 - 06:48 pm: |
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Yes, you are correct-the diaphragm setting lever is in the down position after exposure and remains there until the shutter is cocked so it certainly could cause a squeaking noise during shutter winding. You mentioned that the prism can be cleaned when the mirror box is removed but you do realize that on the A-1 the fresnel and bottom of the prism can be cleaned easily since the fresnel screen drops out through the mirror box.
Bill |
Aphototaker
Tinkerer
Username: Aphototaker
Post Number: 262
Registered: 12-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, September 08, 2010 - 07:48 pm: |
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That is interesting. I was under the impression that to reach the underside of the prism, one has to go from the top, either remove the flex or take out the mirror box.
How does one drop the screen down? There is no notch (like in AE-1 Program) or tabs (like in EOS 50e) that one usually presses to dislodge the frame holding up the screen. I was under the impression A-1's focusing screen is not user changeable, but I could be wrong.
The only thing I see is a black screw in the middle just above the mirror foam in the black metal segment. I have shown a macro photo of the part.
If you can explain how to do this, that would be really great!
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Brcamera
Tinkerer
Username: Brcamera
Post Number: 30
Registered: 08-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, September 08, 2010 - 07:55 pm: |
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Just remove the black screw, the screen and frame will drop out..
Bill |
Aphototaker
Tinkerer
Username: Aphototaker
Post Number: 263
Registered: 12-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, September 08, 2010 - 08:12 pm: |
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Got it. Thank you.
I had to lift the foam end edge of the metal segment a bit and it popped out. The screen and its frame then dropped down.
Right above the screen, and below the prism, is the fresnel lens , also in a metal frame. Is that supposed to drop down as well? I tried to pry it down to reach the prism face, but I don't want to force it before knowing that I should. |
Brcamera
Tinkerer
Username: Brcamera
Post Number: 31
Registered: 08-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, September 08, 2010 - 09:24 pm: |
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Once you remove the focus screen that is as far as you can go from the mirror box. The lens that you see above is the condenser lens and it will not drop out through the mirror box.
Bill |
Aphototaker
Tinkerer
Username: Aphototaker
Post Number: 264
Registered: 12-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, September 08, 2010 - 09:45 pm: |
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Ah! I see. I need to reach behind the condenser lens, however, to reach the prism face. Thanks for the pointer though.
I will think about how to proceed. If I can reach the diaphragm lever gears from the top or from the bottom, while avoiding the variable resistor, that might be sufficient. I will leave the prism face for another adventure day. But if I can't deal with the gears like that, then I will just wait till when I have some time on hand to do this project of taking out the mirror cage.
Regards. |
