Incoherent cycle across multiple speeds

Symptome

The body behaves inconsistently across several shutter speeds or across the whole range:

• all speeds appear to run at once
• Bulb may be incorrect or inoperative
• the body may look chaotic and then almost functional
• failures may appear mostly after rest or on the second release

Contextes

• Cold body
• After rest
• On the second release
• During partial improvement after recap or cleaning
• Combined with other symptoms such as immediate closing, inoperative Bulb, or abnormal mirror-up behavior

Causes a envisager

• Insufficient or unstable power supply
• Faulty ground
• Sequence contacts or switches
• C1 / C2 capacitors depending on the model
• Reset or mechanical sequence issue
• Incomplete mechanical return in the MS clutch / 1st curtain brake area

Checks utiles

1. Look for a pattern: cold body, after rest, on the second release, or depending on the selected speed.
2. Check the basic electronic suspects first.
3. If the body becomes much better but not stable, inspect the mechanical return points.
4. Observe the mechanism directly in the clutch / brake area if access allows it.

Heuristique

When a Mamiya 645 goes from total chaos to an almost functional body, the diagnosis often has to be widened: it is not necessarily a simple electronic fault, and a mechanical sequence issue may still remain.