Diagnose an incoherent cycle

Objectif

Provide a practical method for diagnosing a Mamiya 645 whose cycle seems inconsistent on one or more speeds: release too fast, incorrect Bulb, curtains that appear to leave together, or behavior that changes after rest.

Prerequis

• Check the power supply and battery condition
• Use battery check as a quick clue if the body and model allow it
• Work with the body closed or partly open depending on what can be observed
• Note behavior across several speeds, including Bulb if accessible
• If possible, compare with a mechanically known-good body

Etapes

1. Record the symptom precisely.
2. Note whether behavior changes when cold, after rest, or depending on selected speed.
3. Check priority electronic suspects first: power, ground, contacts, switches, C1, C2.
4. If the body goes from total chaos to 80-95% functional, widen the diagnosis to mechanical causes.
5. Observe sequence return points and the clutch / brake areas before endlessly reworking solder joints.
6. Validate the chosen hypothesis with repeated tests, after rest, and with measurement if the tools allow it.

Validation

• Consistent behavior across several speeds
• Stable repetition after rest
• Correct Bulb if the model allows it
• No immediate closing or incoherent cycle over a series of tests