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Re: Unusual Rank Problem...

>Here's a stumper for you: 
>    Touching the film just before it enters the wheel indicates that 
>the film itself is vibrating!  This vibration is then translated through 
>the tach board resulting in an audible flutter.  When the MagnaTech is 
>not running in interlock, it is very stable. 
>Modern Video 
>Phila, PA
I have seen a problem where the film on the mag machine flutters due to a
ground loop caused by the mag frame ground on the biphase interlock
connector being connected, instead of the signal ground. I rembemer that
with one mag in stop the flutter could be observed as oscillation of its
sprocket. In one strange case this ground loop also caused the capstan to
oscillate in a similar fashion when the film was parked. As soon as
interlock was defeated, the problem vanished in both transports. If you are
seeing related symptoms, try connecting the interlock ground to biphase
signal ground, and ensure the Mag frame ground does not connect to the Rank
mag tacho ground. This should solve it. Magnatech at one time sold add on
inline optoisolators  that plugged to the interlock buss to alleviate
similar problems.  


Craig Nichols
Telecine Engineer