stf-8300 shutter problem

I have a STF-8300 purchased in June 2016 that's been boxed until last month. In the last couple of days it appears the shutter has been blocking the whole frame, or the left part at an angle during about 10% of images captured. I'm using it with a fw8 filter wheel, and the problem happens on any filter position, and if taking successive images with the same filter, so I don't think it's a wheel problem. I've attached a small jpg image taken tonight that shows the most common artifact of no stars on the left side (at an angle).

I found a thread on here from a few years ago that shows a similar image and behavior, he was referred to Bill Lynch for a solution.

Thanks,
Wayne

 

Hi Tim,

I removed the filter wheel from the camera housing and checked the shutter. I think there was plenty of clearance from the shutter to the filter wheel cover (and it was in the right orientation). The shutter blade appears to have enough clearance from the underlying surface it's mounted on. I did notice on the underlying surface a arc-scratch that must have been made by the blade at some point, my guess is during manufacturing. Carefully moving the blade I didn't feel any friction, just what felt like poles from a stepper motor magnet. I took several exposures and while the blade never covered the sensor during the open time, when it first moves from closed it passes open and then continues to cover the sensor, then backs up and opens for the exposure. During at the end of the first move when it apparently should be covering the sensor, the shutter does sometimes not make it all the way, leaving a gap at the corner of the sensor that would allow light in. I don't know what the function of this process where it moves from closed, to open to closed then final open is for. Is this indicative of a problem? I've uploaded a video where it shows the shutter opening 3 times and on the 3rd time it doesn't completely cover the sensor corner. I think this was a "mild" episode and sometimes it travels even less distance and leaves more of the corner open.

Video link:
https://photos.app.goo.gl/Z0ZPOFJE6GLdwwhx2

Now as far as the conditions when this occurred, it was pretty cold out, probably 45 degrees ambient (F) and I had the cooler set to -15C. I only used the camera for about 6 outings, and all previous ones were much warmer (65-70 degrees F and -10C setpoint) and I didn't see this issue. Possibly the cold is factoring into the shutter issue?

I also upgraded the firmware after the videos were shot tonight, the closed-gap issue occasionally still happens. In my warm (72F test room) I never did see the shutter hang over the sensor before or after firmware change.

Thanks for looking at this Tim, I did call your california number tonight and left a voicemail with my phone #.

Wayne