I have an old futurelight 'Miracle' light, a fairly straightforward effects projector with a pair of gobo wheels, colour wheel, a 575 lamp and nice wide angle optics.
It has developped a fault with the rotating gobo wheel which is a 5 position wheel for D size gobos. Rotation is the standard set up with a free wheeling central gear mounted on the shaft of the stepper which selects gobo positions. this freewheeling gear is then driven by another gear mounted on the gobo rotation motor.
The problem is with the gobo select. initial position resetting is achieved by driving the motor into a mechanical stop and this works correctly. gobos can be selected correctly if the motor is moved quickly but if the position is selected slowly (moving the control fader slowly) then the motor intermitantly jumps and dithers and loses position. There is a mechanical damper fitted, The motor shaft extends from the rear of the motor and on this is mounted a disc with a grub screw through its face which then holds a spring loaded nylon (?) plunger which applys friction to the surface of the motor body. Adjusting the grub screw applys greater or lesser friction and this is the mechanism by which I believe this jittering should be controlled.
I have adjusted this friction brake, I have replaced the drive motor and control PCB. I have tried running the system without the gobo rotate driver gear in place. I have tried swapping the rotating wheel with the static wheel (smaller and much less mass) and still the situation persists (although to a lesser extent). I'm at a loss to know what else to try - Anyone have any ideas?
This is an old unit and it has had bits swapped around from other units over the years...
------------- Keep pushing on, things are gonna get better.
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