VIVITAR - Vivitar 285 SPT
Technical service manual for the Vivitar 285 SPT electronic flash unit, a professional-grade flash widely used in studio and field photography. This repair and adjustment guide walks through the calibration procedures for the three main control potentiometers that govern flash performance: potentiometer A (automatic mode flash output), potentiometer B (green LED activation threshold), and potentiometer C (main capacitor voltage). The manual provides exact reference voltage measurements—260V for red LED activation, 295V for green LED engagement, and 330V at full power—essential for accurate tuning with a voltmeter. A detailed rear-housing diagram pinpoints each adjustment location on the unit, removing guesswork during service work. The troubleshooting section addresses the most common field failures: improper green LED threshold calibration leading to unpredictable TTL metering, and erratic or weak flash output caused by cold solder joints at the mounting shoe contact point. Indispensable for service technicians and experienced photographers maintaining or restoring this classic flash model to working condition.
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Document Details
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- Pages
- 1
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- Category
- Photography