Canon ae-1 with odd shutter problem.

roos · Apr 22, 2014

Hi!
I got myself a canon ae-1. Mostly for the lens that was on it and because it was only $10. However its cosmetically in super shape and i really would like to shoot with it. Unfortunatly there is a small problem. The shutter is misbehaving a bit. I know the ae-1 is famous for its squeeky shutter and magnet problem, this however is something else. When its set shooting with slow speeds and/or high iso the shutter opens, but the mirror and shutter stays open until the battery test button is pressed.

If the iso is on 100 the problem starts on about the speed of 1/30 and with iso 25 on about 1/8 and on iso 3200 it doesnt work on about iso 125-250, but below that. The times and the working window changes a bit with the mood of the ae-1, but it always depends on the iso-setting. Aperture doesnt affect it as far as can conclude.

Well, it doesnt sqeek, so its not that. Neither is it the magnet, i took a look and it does do its job of releasing and does nothing on the rear curtain even on the working speeds.

Any help or ideas on how to fix it would be great. If someone would like a very nice looking one sitting on the shelf id be happe to swap it for a working ugly lookin one

frobozz · Apr 22, 2014

Well it doesn't fit your circumstances exactly, but always good to check and make sure that sticky gooey mirror bumper foam isn't holding the mirror up in place...

Duncan

AgX · Apr 22, 2014

I guess that hardly can be overlooked...

Furthermore the return of the mirror is not coupled to the shutter, thus it would not affect shutter closure. It would not even affect the next release. At least I assume so. Never tested on that...

Back to the topic of this thread:
If it was a meter problem the exposure should be off at all times. The shutter is completely electronically, even digitally, controlled. So I assume it to be an exposure calculator issue, thus something in the depth of the electronics.

roos · Apr 22, 2014

Naa, its not the goo. When its stuck, i can tip the mirror with my finger, but the shutter stays open and the mirror flips back. Just like in bulb mode.

roos · Apr 22, 2014

AgX said:
I guess that hardly can be overlooked...
Back to the topic of this thread:
If it was a meter problem the exposure should be off at all times. The shutter is completely electronically, even digitally, controlled. So I assume it to be an exposure calculator issue, thus something in the depth of the electronics.

EDIT:
There is no program mode on this version, so does it really calculate anything. I wonder though, is there a second magnet that controls the rear curtain that is not in plain sight even with the cover off?

AgX · Apr 22, 2014

Yes, there is no simple capacitator circuit that controls exposure depending on the settings and the light meter result, but everything is digitized.
The Canon AE-1 is the first camera to do this. So it is easy to blame anything on those electronics...

gone · Apr 22, 2014

Have you tried a new battery of known voltage? These cameras can often act up if they don't have the full 6 volts.

roos · Apr 22, 2014

Yes, even tested the new cell

Skickat från min telefon, ursäkta t9 och typos

John Koehrer · Apr 23, 2014

AgX said:
Yes, there is no simple capacitator circuit that controls exposure depending on the settings and the light meter result, but everything is digitized.
The Canon AE-1 is the first camera to do this. So it is easy to blame anything on those electronics...

The AE-1 has a series of resistors that are selected by the shutter speed dial. They're directly under the dial.
I don't recall for sure if the AE-1 had digital circuits, It does have ICs but aren't digital, basically miniature analog devices.

There are three magnets in the camera, two are under the bottom cover, the third I believe but don't clearly remember if it's on the side of the mirror box or not..

The AE-1 is very sensitive to voltage. When you read V with a voltmeter you're only reading surface voltage. It puts no load on the battery. I've seen cameras work for two or three exposures then not trip. Set aside for a few minutes the camera will work again, for another shot or two.
The mirror has nothing to do with closing the shutter.
The operation goes like this:
Shutter button closes a switch and releases the mirror. The mirror actually releases the shutter curtains. When the curtains close, the mirror returns to the start position

AgX · Apr 23, 2014

John Koehrer said:
It does have ICs but aren't digital, basically miniature analog devices.

The circuit has A/D transformers surrounding a central CPU.

David Lyga · Apr 23, 2014

John Koehrer said:
The mirror actually releases the shutter curtains. When the curtains close, the mirror returns to the start position

This is correct, John, and that is why on the AE-1 there is a bit of delay from the time you press that shutter button to the time the curtains actually activate. - David Lyga

AgX · Apr 23, 2014

John Koehrer said:
The mirror actually releases the shutter curtains.

Is that so? I assumed there was just a time delay. Especially as the the whole thing is not only dependent on the mirror timely opening but also on the aperture timely closing.

Andrew K · Apr 24, 2014

I suspect there is a broken track in the pcb. The AE1 was the first Canon with a flexible circuit board, and the board goes brittle after a few years. I suspect that one of the tracks has cracked going over the prism and is not communicating inofrmation from one side of the circuit board to the other. From memory when I repaired these cameras in the 1990's we once had to put 8 jumps (put a wire between 2 points on the board) onto the circuit board to make a camera work.

It could also be a dirty contact under the shutter or ASA resistor dial - but if you want to remove these set the shutter to B and the ASA to 3200 first, and remember where the tungsten wire goes.

otherwise it's not a fun job getting it all set up correctly again..

cheers

benjiboy · Apr 24, 2014

momus said:
Have you tried a new battery of known voltage? These cameras can often act up if they don't have the full 6 volts.

If they can't make the full 6 volts they drop dead, they have a wheatstone bridge circuit to ensure that in this eventuality they don't give increasingly incorrect exposures over time.

John Koehrer · Apr 24, 2014

AgX said:
Is that so? I assumed there was just a time delay. Especially as the the whole thing is not only dependent on the mirror timely opening but also on the aperture timely closing.

Hi,
The release button is just a switch that energizes the release magnet. The shutter release is actually mechanical and begun by the mirror striking a lever.
All SLR''s work like this digi's don't count. They're not real, just fig newton's of your imagination.

Any SLR will have a delay of several milliseconds. That's one thing that makes a rangefinder a bit quicker responding. As I recall it's about 30-50% faster.

AgX · Apr 24, 2014

Yes, in a true mechanical camera letting the mirror do the release would be the most simple approach. It saves a true delay device.

Canon ae-1 with odd shutter problem.

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