Stepper Motors for Abstract VR8R

[Neil Hampson]

I know this has been discussed before, but I can't find much on a search. I have just bought 2 VR8r cheaply to complement a couple of VR8s we have in a community rig. however the units both power up and both strike however it would appear that a few of the Steppers are goosed. the units were very dirty inside and I assume they have overheated over time. My question is there appars to be a few different model numbers of motor between the units. Are they fairly universal motors available cheaply or does each function require a specific model of motor. The units have obviously been opened up before and tinkered with but I would like to get these running again Luckily the motor drivers and electronics appear to be OK.

Can anyone recommend a source or relevant part number for the motors.

I need 1 x Pan motor, 2 x gobo select, 2 x gobo rotate.

There appears to be a multitude of similar part numbers on the motors, the one for gobo rotate is 'Type 17HS0601-08', gobo select is an -17HS0601-03 but google doesn't find anything.

Thanks in advance.

[timsabre]

Any size 17 unipolar (6 wire) stepper should work here.

 

Have you checked it's not the driver chips by swapping motor plugs around, they sometimes fail too. Also could be damaged wiring. It was unusual for the actual motor to fail.

 

I'd be interested to know how many VR8's are still in operation out there. Seems like a long time since we were demoing them at Plasa.

[Neil Hampson]

Thanks for the info, I was thrown by the act that nearly every motor that's visible has a different part number, even the same duty between units sometimes have different part numbers. Of the ones that are fairly easy to get to (the tilt motor) I have been able to check the drivers are OK. Looking at the internals there is an obvious heat build up under the cover that the fan is just not shifting. The gobo wheel and the rotate are fairly close to the light path and I think it's heat damage as much as anything else, the motors appear seized as they are very stiff yet others seem fine (pan and colour work perfectly) the units do look as if they have been poorly stored in the past. Are they 1.8 degree or 0.9?

There must be hundreds of these units still in use, especially in community places like ours, they are fairly bright, simple and most importantly only 4 channels (a huge bonus when you have a 24 Channel desk)

 

I've managed to get some sensible search results from the forum now and been doing some reading, but everything is about 10 years old now. I'd forgotten quite how old they are!

[pg720p]

Hi.

I have a selection of VR8 steppers & possibly a couple of old VR8's if you are interested?

[timsabre]

They are 1.8 degree

[Neil Hampson]

Hi.

I have a selection of VR8 steppers & possibly a couple of old VR8's if you are interested?

 

I need to take the second unit apart to make sure what I need, but I believe the units are salvageable. I have ordered a single stepper from FleaBay for £12 but I've noticed it's a 12V motor and I actually didn't check what the VR8 drive is (mainly because it's not labeled on the unit what the voltage is, I simply assumed 12V. I have a feeling I will need more motors for unit 2, if you can let me know how much, and if you have a pair of working VR8's I'd be interested for the right price.

[timsabre]

They are 12v motors

[Neil Hampson]

After firmly believing I had these two VR8r's under control a new problem has presented itself. The shutter motor on one of the units went belly up so I replaced it with one of the new units I bought, the unit responded and on the bench it will run for hours without ant problem. HOWEVER. when in the rig (only difference is that the unit is mounted differently 45deg with the mirror at the top pointing down as oppesed to on the bench where it's on it's back) the light misbehaves. The shutter will work correctly and then after a period of time it will 'over close' giving light out of the other side of the flag, on subsequent cues this either slowly resoves or gets so bad it is so much over-closed it is actually working in reverse, this can also cause the whole thing to become confused and throw out the gobo wheel which I think is on the same driver chip. There is no trim on the shutter so I cant play with that. reinisialising the unit will always work for about an hour.

 

The flags and wheels are pretty much seized onto the shaft of the motors as a helpful previous owner has rounded out the grub screws (very easy to do I admit) so I can't easily swap out motors. Is it worth swapping out the driver chip or is this unlikley to be the cause? should I be looking for an OEM motor? although the old motor does display this dendancy as well. One think Ive not done is tried to re-seat the chip.

I was thinking of reducing the limits of travel on the bump stops to see if that made any difference but I don't know if it will confuse it even more.

It's a shame to have to ditch a pair of great little units for the sake of one iffy flag.

 

Any advise would be appreciated.

[timsabre]

If it moves smoothly it will be either friction in the motor, or the metal blade rubbing on something. If it's jerky when moving it could be the driver chip.

 

They were keen to get the shutter blades moving as fast as possible to give good strobing so the stepper motors are pushed quite close to their speed limits. Added friction from age/heat can make them lose position.

[Neil Hampson]

If it moves smoothly it will be either friction in the motor, or the metal blade rubbing on something. If it's jerky when moving it could be the driver chip.

 

They were keen to get the shutter blades moving as fast as possible to give good strobing so the stepper motors are pushed quite close to their speed limits. Added friction from age/heat can make them lose position.

 

Thanks for the input. Its a brand new motor but not an OEM branded one as I couldn't find any so I bought one with a VERY similar part number that fitted the size and description from a company called Steppers online. The colour wheel motor I also replaced works great. I have been keen to try to resrict the strobing from this unit but of course it generally snaps open. it is always smooth. I wonder if a smaller motor would work as it's only got to move a tiny flag. other than that I might try to find the 'best OEM motor from the other units and try to swap out. THe biggest issue I found was loosening the grub screw without rounding it off.

[Brian]

...I bought one with a VERY similar part number that fitted the size and description from a company called Steppers online.

 

That's likely to be your problem. Unless it's the identical part number from the same manufacturer then they are likely to be different. To get an accurate match you'd need to be comparing the torque/speed/current graphs to make sure they really are the same.

[timsabre]

All the motors in the unit are the same so you could try swapping an original stepper from another function, but you'd have to get the grub screws out.

 

Do the dimmer flags show any sign of being repainted, sounds silly but the weight of the paint can affect the movement.

[jamieshurlock]

I have a handful of ateppers and parts for these if you still need them...