Stepper-motors

[browna]

Hi,

 

I trying to learn about general service of MACS.

 

What are stepper-motors, how do they work, how are they controlled? And anything else you could tell me about them!?

 

Could you suggest any websites that teach you about general maintenance of moving heads?

 

Thanks very much!

[ceecrb1]

to be honest you wont need to go into too much detail with them.

 

with macs, they work or they dont

 

a STEPPER motor is a motor which does just that.

it rotates in stages (try turning one by hand and you'll feel it "ratchet". Those are the steps)

 

pretty simple, driver gives a voltage to turn one way using 2 wires, and using the other 2 wires, a voltage to turn the opposite direction.

 

common problems I've experienced are jamming due to oxidisation and general dirt.

 

take it out the mac and off its chassis, spray a load of de-oxidant/circuit cleaner.. rotate by hand and lubricate..

 

thats it really!

 

most mac problems (in my experiece (repair tech for neomedia)) come down to wiring problems... broken cables, bad connections and so on..

that and the magnetic hal sensors, driver chips and broken diacs!

 

with patience and persistance, macs are easy to repair, far easier than older lamps (mostly due to the "repair friendly" design)

[tokm]

Specific mac maintenance: clicky. Click on 'schools', then on the drop down box, select service.

 

General ML maintenance: Clicky. They've only got a L2 course up at the min, but they do the other levels every so often.

 

If you work for a company that owns Vari*lites or you can prove your regular user of them, you can also do courses on the maintenance of them. Heard a rumour that PRG were relaxing this rule.. Perhaps 'VL Nick' can shed some light on this.

 

I'll leave 'how stepper motors work' to a more experienced mechanical engineer ;)

 

Tom

[maeterlinck]

Google is your friend here. Try searching for 'stepper motor' or 'stepper motor theory'. Both will give you lots of results detailing the operation and control of them. But in brief, as ceecrb1 said, it is a motor that is designed to move in steps, as a posed to a standard induction motor that has a fluid motion continuous motion. It does this by having multiple poles a set number of degrees apart, varying the polarity of the winding causes the motor to move a step. This means they require a special controller that is able to keep track of where the winding is to output the next correct step in the rotation sequence. Because stepper motors move a known amount for each step they often do not require a feedback circuit after initial calibration, however, moving lights tend to have feedback encoders and indexing functions for the position sensitive areas (pan/tilt, gobos etc).

 

 

Edit: Found this looking for something else: http://nanotec.de/page_static__schrittmoto...mation__en.html

Should explain things visually.