Canon A-1 A1 Camera Service Repair Manual

1. Introduction In April, 1976, Canon introduced a landmark camera, the Canon AE-l. It incorporated a very reliable computerized AE mechanism into a compact body that can be marketed at a very competitive price due to revolutionary production techniques. The AE-l has been a huge success and completely changed the face of photo hardware marketing. With the AE-l firmly established as the best selling SLR in the World, design work progressed on a more versitile ver- sion. This work is now complete and the result is the CANON A-l, the Apex of the AE camera world: the highest quality, most durable, most feature laden automatic exposure SLR in the world. The major goals which guided the design of the A-l were: - Incorporation of advanced digital technology - Compact, easy-to-handle body - Compatability with AE-l system components - Interchangeability of parts with AE-l - Improved durability 2. Features 2.1 Five difference automatic exposure modes o Full Aperture TTL Metering Shutter speed priority AE Aperture priority AE Programmed AE Electronic flash AE o TTL Stopped-Down Metering Stopped-down AE at (regardless of the types of lens attached or whether a lens is attached at all). 2.2 The employment of total digital system to process with speed and accuracy all incoming information After converting the brightness information from analog form into digital form, digital computation takes care of information input, calculation, information storage, 1 •

INTRODUCTION The CANON A-l is the pinnacle we have been striving for in an AE SLR-- a completely digitally controlled camera. The mechanical parts are based on, and nearly identical to, the AE-l. To troubleshoot and repair the A-l, experienced gained on the AE-l is important, and consideration of digital timing is necessary. The electrical circuit of the A-l is quite different from the AE-l. The main components are five intergrated circuits, (OPT, INPUT, CPU, OSC / INTERFACE and DECODER DRIVER). Digital signals criss-cross to and from these Ie 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. Special Precautions 1. Many parts are interchangeab le between the A-l and AE-l. However, other parts that appear quite similar to AE-l parts are either slighly different in size, strength or material and are not interchange a ble. Special attention should be paid to parts control to insure that the correct parts are used. 2. The A-l shutt er is controlle d in 1/8 step intervals . For this reas on the 2nd curt a in latch adjustment has been changed. Rather than having a space between the latch and latch cam, they press against each other in this design. 3. Because of the digital control, the positioning of the information in put brushes is very important . Each one has a special check point built into the pattern . This point (called a check pattern or check bit) should be used to accurately adjust the contact. If improperly adjusted, improper exposure or viewfinder information will result. Especially, if the AV brush (Section 2-11) is not correctly adjusted, the error mark (EEEE EE) will be displayed and the shutter will be lock ed. 4. The maximum aperture pin height adjustment (Section 2-8, 2-9) is di ff er ent from the AE-l. See section 2-8 and 2-9 for the co rre ct procedures. This adjustment has a direct effect on the viewfinder information and should be accurately performed. 5. Lock-out volta ge (LV): The low voltage interlock for this camera is 3.1 to 3.5 volts. 1 -

6. When their IC is replaced the R OSC and R ADNUL must be correctly adjusted. The adjustment is different from the AE-l adjustment and it has a direct effect on the viewfinder display . (See Section 4, IC Replacement) . 7. The flexible circuits used in the A-I are high densitity with patterns on both sides. Jumper wires cannot be used. Care should be taken not to crimp or break the pattern when installing the top cover. S. Certain voltages and signals are basic . They are El (Supply voltage) for each IC, CLK (clock pulse) SYNC (07) (the synchronization trigger), I. BUS (input busline) and O. BUS (output busline). 9. In order to understand the A-I circuit, it is necessary to stud y the detail operation of each IC as outlined in section 3 of this repair guide. 10 . The A-I is a system camera . It uses the following major accessories: POWER WIND ER A, MOTOR DRIVE MA, SPEEDLITES l55A and 199A, DATA BACK A and WIRELESS CONTROLLED LC-l as well as all the FD lenses and other abcessories . Oper a tion with the various accessories must be considered whe n repairing the b asi c camera. 11 . Since the mechanical design is similar to the AE-l, the common repair operations ha ve not been included in this guide . Refer to the AE-l Repair Guide . 2

SWITCH TABLE Switch Name Function SWl Metering Switch-L ON at shutter button half strok.e SWl' MD Metering Switch-l Motor Drive metering switch LM SW Light Metering Exposure preview Switch Switch-2 SW2 Release Switch ON at shutter button full stroke SW3 Display Switch Finder display control switch Switch ON - Gnd. Switch OFF . H SW4 Count Switch Shutter time initiation switch r==:O.625El, CTST="L" GND _ SW4 OFF (Count Start) SWS Winding CompLetion SWS-5' indicates winding c ondition. SW "L" • Cod . Wound Rel eased SW5' lID Winding Model AE-l A-l AE-l A-l Completion SW SWS L H H L SW5' H H L L SWS II ME SW5' Di sable SW In series with SW5' t this switch prevents motor drive operation if the multiple exposure lever has been pressed. SW6 AE Lock SW Records and holds measured EV when pressed. (Exposure memory switch) SW7 Power (Kain) Switch A - L switch SW8 Battery Checker Battery Check- 4-5Hz flashing LED (Clears SW (Clear SW) all circuits in mid operation) TIME 1 2 sec . S eU Timer During self timer: operation. LED frequency is 8 Hz for last 2 seconds, and 2 Hz for TIME 2 10 sec. SeU Timer first 8 seconds. spew Stop-down Switch ON when sto p-down lever pushed A-M$W Auto:-Manual SW OFF with lens at "A", ON otherwise AV/TV SW Priority Mode SW Selects aperture or shutter speed priority. 3·

Canon A-1 A1 Camera Service Repair Manual

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