CANON - Canon AT1 Service Guide

Comprehensive service manual for the Canon AT-1 (C12-1501), the second-generation SLR that built on the groundbreaking manufacturing methods established by the Canon AE-1. This technical reference documents the critical mechanical and electronic differences between the AT-1 and its predecessor, with particular emphasis on the match-needle exposure metering system and its extended measurement range. The manual covers complete technical specifications: 35 mm focal-plane shutter SLR, 24 x 36 mm format, FD and FL interchangeable lens mounts, fixed pentaprism viewfinder without condenser optics, electronically controlled shutter speeds, and TTL metering with center-weighted sensitivity. Detailed disassembly sections walk through removal of the top and bottom covers, the electronic components assembly, film counter mechanism, front panel section, and shutter speed dial, followed by step-by-step reassembly and adjustment procedures including match-needle stroke calibration, tension compensation, tungsten wire placement, and maximum aperture correction. The troubleshooting portion addresses common operational issues systematically. Adjustment procedures cover exposure meter deflection checks, battery indicator calibration, and accuracy verification across varying light levels. Full electronic circuit diagrams include pin assignments and timing circuit explanations, with operational sequence analysis and Speedlite 155A flash synchronization details. An essential repair manual and workshop reference for technicians working on Canon AT-1 cameras.