Andreas Thaler
Subscriber
If you want to understand one of the complex digital-electro-mechanical Japanese SLRs from the 70s and 80s from the inside, you can't ignore the manufacturers' service manuals.
In contrast to manuals from later years, which only show a few details and text due to the increasing integration of electronic circuits and mechanical components, the older service documents are practically bubbling over as sources of knowledge and insight.
Processes can be understood
Since there are still a relatively large number of discrete electronic components with traceable conductor tracks that interact directly with mechanical components, processes can be understood fairly clearly. Integrated circuits do not yet appear as total black boxes, and at least the pin assignment reveals what is connected to what.
Highly interesting for everyone who appreciates the combination of analog electronics, mechanics and the first digital components and - together with graphics and technical drawings - wants to get to the bottom of things
At the time, there was obviously a consensus that every component of the camera could and should be replaced. Accordingly, emphasis was placed on providing precise instructions for this. In addition technical processes and connections are also described in depth. This means that the device's functions can actually be overviewed and understood.
Examples
An example from Canon's repair guide for the A-1, p. 63 (paragraphs partially inserted for better readability):
More on page 85:
Finally on page 59:
Technical reading books that show the manufacturers' pride in their solutions
In contrast to manuals from later years, which only show a few details and text due to the increasing integration of electronic circuits and mechanical components, the older service documents are practically bubbling over as sources of knowledge and insight.
Processes can be understood
Since there are still a relatively large number of discrete electronic components with traceable conductor tracks that interact directly with mechanical components, processes can be understood fairly clearly. Integrated circuits do not yet appear as total black boxes, and at least the pin assignment reveals what is connected to what.
Highly interesting for everyone who appreciates the combination of analog electronics, mechanics and the first digital components and - together with graphics and technical drawings - wants to get to the bottom of things
At the time, there was obviously a consensus that every component of the camera could and should be replaced. Accordingly, emphasis was placed on providing precise instructions for this. In addition technical processes and connections are also described in depth. This means that the device's functions can actually be overviewed and understood.
Examples
An example from Canon's repair guide for the A-1, p. 63 (paragraphs partially inserted for better readability):
(7) Others
1) Hybred magnet
When the shutter button is released, a magnet starts functioning the camera.
This magnet, like the one used in the AE-1, is a hybred magnet employing a permanent magnet and an electromagnet.
However, the hybread magnet installed in the A-1 employes an additional alloy, made of rare earth element (samarium) and cobalt, in the magnetic body section.
2) Temperature compensating resistor
A wire-wourd resistor was used for the temperature
compensating resistance in the AE-1.
In the A-1, reliability is further increased by employing a special metal film resistor.
More on page 85:
The CANON A-1 is the pinnacle we have been striving for in an AE S L - - a completely digitally controlled camera.
The mechanical parts are based on, and nearly identical to, the AE-1. To troubleshoot and repair the A-1, experienced gained on the AE-1 is important, and consideration of digital timing is necessary.
The electrical circuit of the A-1 is quite different from the AE-1.
The main components are five intergrated circuits, (OPT, INPUT, CPU, OSC/INTERFACE and DECODERDRIVER).
Digital signals criss-cross to and from these IC and to their mechanical interfaces. To repair the camera, signal sequence and timing must be understood.
Digital basics, including code reading, and oscilloscope operation are other necessary skills.
Finally on page 59:
4) Ultra smooth double sided flush surface plate
The aperture control system of the A-1 is operated in the following manner.
The brush, that is driven by the lens aperture signal lever, slides over the segmented aperture value electrode plate pattern at a high speed.
The number of pulses of the ON/OFF signals that are generated at this time are counted and the f-numbers are digitally detected.
Technical reading books that show the manufacturers' pride in their solutions

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