Canon A-1 repair advice wanted

Mice · Feb 2, 2022

Hello, I got a functioning canon A-1 from ebay, and it's got two little problems right now. There is a patch of fungus somewhere within the prism. I know it is not on the eyepiece or the back of the prism next to the eyepiece, since I could access these points, and looking through the prism without the eyepiece shows that the fungus is not on the plane of the back of the prism. I know it's not on the focus screen, but the underside of the prism within the camera body appears to have some sort of surface separating the prism from the body. I'm almost certain that the fungus is on the underside of the prism, but I can't get to it with simple disassembly. Would I have to remove the mirro box and completely expose the prism to get to this? See photo.

The second issue is that the axle of the film rewind lever is tilted. While winding, the angle is fixed in the same direction. While the systems spins, I'm not sure if it will result in slight deformation of the film as I advance frames. If it's a reasonable fix, I'd like to get it done to prevent more trouble.

Alternatively, if the risk to repair for me to do this myself is high, does anyone have an estimate on how much it would cost to be professionally done?

Thanks a bunch.

flavio81 · Feb 2, 2022

The fungus: Just clean it, you are looking at it. Get a q-tip or something similar and clean it.

As for the rewind shaft, i'd leave it alone. Beneath the ISO dial there are circuits that could be damaged if you force the shaft for correcting it.

Mice · Feb 2, 2022

flavio81 said:
The fungus: Just clean it, you are looking at it. Get a q-tip or something similar and clean it.

As for the rewind shaft, i'd leave it alone. Beneath the ISO dial there are circuits that could be damaged if you force the shaft for correcting it.

I have tried to clean it with a q tip, but I can see that the layer the cleaning solution is on is distinctly separated from the fungus.

AgX · Feb 2, 2022

At the A-1 there is between the solid prism and the groundscreen/fresnell lens a field lens !

Mice · Feb 2, 2022

AgX said:
At the A-1 there is between the solid prism and the groundscreen/fresnell lens a field lens !

Ah I see, is there any specification that refers to this field lens in another term, I can't find anything referring to it. Better yet, is there an available disassembly guide for this do you know?

AgX · Feb 2, 2022

The usual term for such lens is field lens as I used. Canon used the term condenser lens for it. In any case it is a plano convex lens.
Basically a field lens is needed to illuminate well the eyepice, but there are various ways to design and to locate such lens.

DWThomas · Feb 2, 2022

Here's a page (14) from the service manual with a cross-section of the finder:

You can currently find the manual here.

(A-1 owner ... )

AgX · Feb 2, 2022

This graphic does not tell more than I said above.
More important to the OP would be to know how to access this lens. To my understanding the lens is fitted from above the mirror box, this means access is from above thus necessitaing removig the prism. However the space above the prism is stuffed with electroncis. Alternatively one could take out the mirrorbox with the prism above from the rear, but this would need taking off the front leatherette.

We got amongst our fellows an experienced repairer, maybe he can chime in.

Mice · Feb 2, 2022

I'm very grateful for all the information you all have contributed so far. I will have to do more research to see if I can find a complete dissembly to the field lens. I do not want to be pulling screws blindly.

AgX · Feb 2, 2022

Pulling out the mirrorbox would yield as benefit that one gets access to the mirror mechanics and be able to do the likely necessary lubricating.

flavio81 · Feb 3, 2022

Mice said:
I have tried to clean it with a q tip, but I can see that the layer the cleaning solution is on is distinctly separated from the fungus.

You are correct, and thanks @AgX for clarification. Since i don't service the A-1, i was oblivious to that detail.

The technician would have to disassemble the camera top (without damaging it -- something that requires dedication on this camera model) and very, very carefully, try to remove the prism without damaging the electronics. If it was my camera, i'd leave it alone.

AgX · Feb 3, 2022

The patch is close to the focal plane and thus maybe annoying. But yes, unless one got some experience at camera repair, especially with bodies stuffed with parts, the endeavour may end in something no longer fun. If the patch is not annoying and cleaning postponed, one may use UV light on the patch and in any case avoid humid long-time storage of the camera.

DWThomas · Feb 3, 2022

The full service manual which I linked to has, toward the end, some disassembly info. One segment of that shows removing or swinging down a cover in the front to gain access to the focus screen for switching it. Don't know if that might get you a path into those surfaces or not. It might be worth some study.

That finder optical package is rather complex with adding the ability to bring in the LED 7-segment displays and such.

AgX · Feb 3, 2022

The OP already had the screen swung do get access to the patch, only to find it inaccessible from there. The field lens to all one can deduce sits in a deep cage which is mounted from above. The OP sure may find out whether detaching and taking out of that cage is possible from the front. If not he likely got the two alternatives I described. For both the top cover has to be taken off, from then on he may decide which way seems less bothering to him

DWThomas · Feb 3, 2022

^^ ^
Yes, I have two A-1 bodies, but I am not inclined to experiment!

The one had some damage when it fell out of a fanny pack, but last time I tried it, it didn't sound good but still functioned. I figure for now, it's a "parts" source should I ever be inclined to wade into repairs (which is unlikely).

AgX · Feb 3, 2022

Mice said:
The second issue is that the axle of the film rewind lever is tilted. While winding, the angle is fixed in the same direction. View attachment 297266 While the systems spins, I'm not sure if it will result in slight deformation of the film as I advance frames.

flavio81 said:
As for the rewind shaft, i'd leave it alone. Beneath the ISO dial there are circuits that could be damaged if you force the shaft for correcting it.

I do not see a big problem with that bent shaft, as long the crank runs freely. Otherwise only the varying inclination of the crank button may be annoying, but I got models where such even is designed into the camera.... In any case it does not have effect on film transport. To be so, it would have been bent to a degreec that you could not move it in or out.
In case you want to rebend the shaft, take it out of the body and into a proper vise and use proper tools.

Mice · Feb 15, 2022

Well, I managed to recoup my money on the item so it is now a functional source of parts. I am kind of interested in seeing if I can get access into the field lens to try and clean it up. If I botch the camera no harm no foul. I might see if a friend is interested in having it and doesn't mind the fungus. Sadly, it seems in my tinkering I've biffed something in the exposure lock system. I've tried removing the contacts and cleaning them but it only works briefly. I believe I may have shorted something deeper inside. Back to the work stand ...

John Koehrer · Feb 17, 2022

RW has had a small bump(bimp) bending it. Question for you.............Is it bothering you enough to possibly break a board, solder joint or flex?
I wouldn't go fiddling with it unless you can get a lot more information There are two long screws holding the mirror box in place. one on each
side of the evepiece and two at the front of the prism frame. The flex under the wind lever may have to be folded over the prism to remove the
at that point it may be possible to remove the prism with out removing the mirror box. You MAY have to unsolder some wiring Take
notes, photos and be vey careful about color coding of wires, the had a a couple of different circuit boards through it's lofe.

Canon A-1 repair advice wanted

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