Canon A-1 camera issue only in bulb mode. all of others works properly.

harley2878 · Sep 28, 2020

Have 4 Canon A-1. Same issue. use a new battery (6v) When set to Bulb. Press the release button first curtain moved mirror up. Loss the button no second curtain moving(releasing) . short the mg3. the second curtain can be moved(releasing). and when I press the battery checking button can be moved(releasing). and switch the double exposure switch can be moved(releasing). and remove the battery out(power off). Those actions mean lower battery volt or power off I think.
I doubt the release button(SW) has a problem. But when using a low volt battery (5.3v). above issue disappear. so it looks not the release SW issues.
How to fix it?

AgX · Sep 28, 2020

Welcome to Apug (Photrio) !"

I got difficulty with your wording.

For instance:
-) what does "mg3" mean?
-) what does "the second curtain can be moved" mean? Releasing it the proper way, or somehow by hand?

harley2878 · Sep 28, 2020

the mg3（magnet No.3） is the second curtain release magnet. The curtain always releasing properly.

shutterfinger · Sep 28, 2020

AgX said:
I got difficulty with your wording.

I think he's using an online translator and its doing a poor job.

harley2878:
download https://learncamerarepair.com/downloads/pdf/canon-A-1-Service-Guide.pdf and https://learncamerarepair.com/downloads/pdf/Canon-A1-SPT-Guide.pdf
hopefully they translate correctly for you. use the terms used in the manual and service guide as they are in English for the best responce.

I stand corrected on the translator.

John Koehrer · Sep 29, 2020

Once upon a time I serviced one of the A model canons that would fire once and not cock. set the camera to the side
and let it rest for a while and it would trip but repeat the failure. The battery would measure good initially but removed
from the camera immediately after firing it would be .1V of so low.
Kinda cute but the A cameras are really picky about voltage. "shrug"

AgX · Sep 29, 2020

Is that low voltage related well releasing related to the CPU?

shutterfinger · Sep 29, 2020

When testing batteries for cameras use a good digital voltmeter. Battery testers do not load batteries adequately for camera use, they do fine for flashlights.
A 6V battery when new will read 6.6V to 6.49V depending on age. A battery that reads 6V or lower will not operate a camera properly.
A 1.5V battery will read 1.55V when new. A battery that reads 1.5V or lower will not run a camera properly.
Camera electronics require a given voltage range to operate in and are current dependent. A low battery will not provide sufficient current to operate the components.
A new battery out of the package should be good but the guarantee does not ensure that it is, just that it will be replaced if it is not.

With regard to the camera in this thread and its problem dirty/tarnished switch contacts, battery contacts or dried lubrication in the shutter mechanism are the major culprits, faulty circuits, circuit contact points, or components are a secondary culprits.

AgX · Sep 30, 2020

But the point in this case is the contrary: only with the lesser voltage the shutter releases.

But as long it only failed with one sample of battery I rather would blame that battery of not delivering enough current (raised inner resistance) in spite of having nominal and even higher voltage than the other, effective battery, than something being wrong with the camera.

harley2878 · Oct 2, 2020

Thanks all of you.
I m sure its not a battery problem.
I found another case. I believe it's the same with me.
https://www.reddit.com/r/analog/comments/10ilq8/canon_a1_stuck_in_bulb_mode/

AgX · Oct 2, 2020

In case I would be sure it is not the battery, I would shortcurcuit the camera for a moment.
That means taking out the battery, and bridging the contact in the battery and then pressing the release for a few seconds.
Our electronics fellows might chime in here.

Canon A-1 camera issue only in bulb mode. all of others works properly.

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