What the thread found

• A loose potentiometer at the motor can cause uncontrolled movement in one direction, which can be temporarily managed by adjusting the potentiometer slightly.
• Thermal drift in an older amplifier may cause asymmetrical motor speeds that equalize as the unit warms up after extended operation.
• Aged capacitors and corroded solder joints in vintage amplifiers can accumulate and cause multiple performance degradations that require systematic inspection of all connections.
• An improperly configured mode switch near the second channel can cause erratic behavior if left in slave mode while operating with a single motor, and removing or correctly setting this switch improves precision.
• The Seitz amplifier's two channels have different operating characteristics—Channel 1 prioritizes speed and range for focus control, while Channel 2 offers slower speed with smoother response optimized for iris control.
• Potentiometer wear on the transmitter can cause jerky motor movements that improve after replacement.
• Automatic switching between RF and cable modes on the transmitter can malfunction independently of amplifier issues.

Depends on

• The original diagnosis by a local service technician was incomplete and required multiple repair attempts by different specialists.
• Communication in English presented challenges in describing all technical details of the repairs performed.
• Original amplifier documentation with schematics was not available to the user, limiting self-diagnosis options.
• All integrated circuits in the amplifier lacked identifying labels, making component-level diagnostics difficult.
• The motor unit was approximately 20 years old at the time of these issues.
• Repair details from the final successful technician were not fully documented due to language barriers.

Parts

Follow Focus

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