BL-3 shutter mirror not spinning

[Paulo Arellano]

Camera has been in storage for a while, loaded some film and noticed the viewfinder was completely black, removed lens and the shutter mirror is not spinning, am i wrong in thinking it should spin when I turn on the camera? everything sounds fine and film goes through just fine. 

[Steve Switaj]

Don't know about the BL3, but the BL4 has two berg-chain type belts inside.

The large main belt does most of the work, connecting the motor, sprocket, intermittent movement and mag drive.

A smaller belt drives off the main belt, turning 90 degrees to drive the shutter.

Here's a picture from Richard Bennett's website...

    https://cinemagear.com/blog/2024/08/16/arri-bl-4s-finally-on-the-bench/

Maybe you've lost your shutter drive belt?

 

[Fabian Schreyer]

9 hours ago, Paulo Arellano said:

am i wrong in thinking it should spin when I turn on the camera?

Of course not. I also would suspect that one of the belts has degraded and just fell apart. 

[Paulo Arellano]

it appears as you guys mentioned, the shutter belt has most likely snapped or deteriorated. The main belt is still intact but should probably be replaced as well. Any recommendations? Im calling visual products in Ohio later today.

[Phillip Mosness]

Visual Products would be the first place I'd call.

Here's a video about this.