How to Open Canon AT-1

Opening the AT-1 is not a job for the faint hearted. Firstly, why would you even want to open the top cover? This conceals of some extremely sophisticated Japanese designed electronics, and it is very unlikely that the "average" person in the UK can repair it. You could have memberships to institutions and letters after your name, due to an overpriced education, but it does not necessarily follow that you will be able to repair it. Even with minimal electronics, this camera requires a custom microprocessor integrated circuit (IC) µPC1102 manufactured by the NEC Corporation. This IC consists of comparator operational amplifiers and digital logic gates, and troubleshooting it is a complex task.

A string couples a variable resistor, situated at the film rewind end, to the concentric shutter speed and ASA dials at the film advance end. When you move the dials, the string transmits the force to move the variable resistor at the other end. When opening this camera, the first thing to remember is to set the film speed dial to "B", and the ASA setting to 3200. This is because they are using a spring-loaded string, which snaps and breaks if the dials are on the other extreme setting. Please refer to the Canon AE-1 Repair article for more information about this string.

If you manage to open it without breaking the string, the first thing to do is to note how it passes through a series of pulleys connecting one end to the other.

On this camera, there is a short wire connecting between the hot shoe socket and the flex circuit and it is probably better to desolder it so that the top cover is completely detached.

At this point, you have the opportunity to clean the inside surface of the viewfinder lens and the opposing pentaprism surface.

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