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Author Topic: Gobo and Color Wheel Alignment Issues on my ACME iMove 8S Moving Head Spots  (Read 1162 times)

Stuart Murphy

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Hi Guys,

I really hope someone smarter than me can give me their idea on this:

I have two moving head spots - they are the ACME iMove 8S model, so pretty old now, in fact Acme in China tell me they don't supply spare parts for them now.

Anyway, I reset the lights to default to start off, and immediately as it then starts to perform, the color wheels in BOTH lights don't stay aligned properly, they're like a click or two out - enough to make the color half/half of two different colors, and the same with the gobo - enough to be up to half the gobo pattern missing due to it being misaligned. They're both totally random in their amount of inaccuracy, independent of each other. I've checked the allen screws on the wheel shafts - they're solid, and I've replaced the small circuitboard in the head, no change. I even replaced the capacitor.. no change there either.

I can see when I factory reset the unit that all 4 wheels go back to their correct default positions by hitting their physical stop posts, and they look perfectly aligned to the eye, which is easy to see as the cases are off the lights.

Oh and also, one of the lights also has an issue with the head not strongly holding its tilt function - the pan function is strong and perfect, but the tilt function is so weak, it can't flip the head right over now, and can only muster enough stick to get a spot approaching vertical, before it lazily gives up and softly clicks back down under its own weight to a lazy horizontal medium. I've swapped out all the parts (the motor in the arm) with other working parts that I can think of - and there are no teeth missing from the belt, but still no joy. When the power is on, the head is simple to tilt with the hand as there's almost no resistance - just a weak clicking sound. Whereas the other "good" light is fully resistant and can't easily be forced or clicked out of its tilt position - dramatic difference between the two.

Oh, and I also swapped the main circuit boards out in the base too - which didn't change anything.. :-/

Might anyone know what's going on? At this point, I'll take anything before I throw them in the bin.
« Last Edit: March 25, 2019, 06:34:37 am by Stuart Murphy »
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TJ (Tom) Cornish

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Hi Guys,

I really hope someone smarter than me can give me their idea on this:

I have two moving head spots - they are the ACME iMove 8S model, so pretty old now, in fact Acme in China tell me they don't supply spare parts for them now.

Anyway, I reset the lights to default to start off, and immediately as it then starts to perform, the color wheels in BOTH lights don't stay aligned properly, they're like a click or two out - enough to make the color half/half of two different colors, and the same with the gobo - enough to be up to half the gobo pattern missing due to it being misaligned. They're both totally random in their amount of inaccuracy, independent of each other. I've checked the allen screws on the wheel shafts - they're solid, and I've replaced the small circuitboard in the head, no change. I even replaced the capacitor.. no change there either.

I can see when I factory reset the unit that all 4 wheels go back to their correct default positions by hitting their physical stop posts, and they look perfectly aligned to the eye, which is easy to see as the cases are off the lights.

Oh and also, one of the lights also has an issue with the head not strongly holding its tilt function - the pan function is strong and perfect, but the tilt function is so weak, it can't flip the head right over now, and can only muster enough stick to get a spot approaching vertical, before it lazily gives up and softly clicks back down under its own weight to a lazy horizontal medium. I've swapped out all the parts (the motor in the arm) with other working parts that I can think of - and there are no teeth missing from the belt, but still no joy. When the power is on, the head is simple to tilt with the hand as there's almost no resistance - just a weak clicking sound. Whereas the other "good" light is fully resistant and can't easily be forced or clicked out of its tilt position - dramatic difference between the two.

Oh, and I also swapped the main circuit boards out in the base too - which didn't change anything.. :-/

Might anyone know what's going on? At this point, I'll take anything before I throw them in the bin.
This sounds like a mechanical issue to me.  Are the wheels easy to turn?  Are there any obstructions anywhere? 

On some of my movers I found that the ball bearings in a few places seized up due to the oil inside getting cooked and turning into maple syrup.  I pulled the bearings out and soaked them in acetone and the crud came out.  Since they don't rotate very much in the light, I put them back in without any lubricant, which is probably how they should have been in the first place.
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Jeff Lelko

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Hi Stuart.

The color/gobo wheel issue sounds like a motor problem to me.  One sign of end of life motors is that they’ll randomly drift, especially after the fixture has heated up.  They’ll usually calibrate fine but won’t hold their position much longer after that, particularly if the motor tries to move quickly.   

The tilt issue might be a bit trickier to diagnose.  Since you’ve already replaced the motor (hopefully with a known good one), my next thought would be the power supply, especially if the unit uses a power supply for motors that’s separate from the power supply for lamp and logic.  One thought is to start swapping parts between the good unit and the bad unit until you find the problem.  At least that’s a free approach to try!

Obviously, there’s a fine line between paying to maintain old fixtures versus buying new.  Hope this helps!
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Stuart Murphy

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Hi Stuart.

The color/gobo wheel issue sounds like a motor problem to me.  One sign of end of life motors is that they’ll randomly drift, especially after the fixture has heated up.  They’ll usually calibrate fine but won’t hold their position much longer after that, particularly if the motor tries to move quickly.   

The tilt issue might be a bit trickier to diagnose.  Since you’ve already replaced the motor (hopefully with a known good one), my next thought would be the power supply, especially if the unit uses a power supply for motors that’s separate from the power supply for lamp and logic.  One thought is to start swapping parts between the good unit and the bad unit until you find the problem.  At least that’s a free approach to try!

Thanks a lot Jeff. Yes, good advice - I've been scavenging and swapping parts between the two units - I haven't swapped the gobo and color wheel motors, as both lights suffer the same fault. I did swap the tilt motors though, but that didn't solve the tilt issue. I swapped the belts too, so far no fix though. Will check if there's a tilt sensor somewhere - maybe I can swap those, but have swapped most other things. I don't get the electric/electronic side of it all either, so other than swapping out circuit boards, that electrical side of it remains untried.

Dang.. hard to find faults!
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Stuart Murphy

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This sounds like a mechanical issue to me.  Are the wheels easy to turn?  Are there any obstructions anywhere? 

On some of my movers I found that the ball bearings in a few places seized up due to the oil inside getting cooked and turning into maple syrup.  I pulled the bearings out and soaked them in acetone and the crud came out.  Since they don't rotate very much in the light, I put them back in without any lubricant, which is probably how they should have been in the first place.

Thanks TJ.. No impairments that I can see. I wasn't so keen to pull too many bits out, but I'll have to bite the bullet or dump them I think.. Will give your suggestion a try. Thanks v much.
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Jeff Lelko

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I don't get the electric/electronic side of it all either, so other than swapping out circuit boards, that electrical side of it remains untried.

No worries, and I get it.  I'd doubt it's a tilt sensor and so long as you don't observe any belts or pulleys slipping it won't be that either.  If you've ruled out the motor my next guess is power.  Seized or destroyed bearings can definitely reek havoc in a light too but usually manifest as something very stiff and unable to move - not the opposite as you describe. 

Regarding electrical, just follow the wires.  This can be easier said than done as there are quite a few of them, but generally just trace everything upstream.  Generally speaking, the motor will plug into a driver PCB.  This may just be a single large board or it might be split into several discrete PCBs depending on the fixture.  Try swapping that board if you haven't already.  From there, look for larger gauge wires that will route to a power supply.  Again, there might be just one or several.  Swap that too if you haven't already.  By then, you should have a working tilt motor if borrowing parts from the good unit.  Hope this helps!
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Stuart Murphy

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If you've ruled out the motor my next guess is power. Regarding electrical, just follow the wires.  This can be easier said than done as there are quite a few of them, but generally just trace everything upstream.  Generally speaking, the motor will plug into a driver PCB.  This may just be a single large board or it might be split into several discrete PCBs depending on the fixture.  Try swapping that board if you haven't already.  From there, look for larger gauge wires that will route to a power supply.  Again, there might be just one or several.  Swap that too if you haven't already.  By then, you should have a working tilt motor if borrowing parts from the good unit.  Hope this helps!

Jeff, mate you've given me renewed inspiration! I'll head down to the shed now and attack it with renewed vigour. I did swap out the main elec circuitboard in the base with a known good one, so presumably if I go upstream further and swap out the transformer maybe, and a few other things earlier in the chain, I'll find the fault there? Tbc..!
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Jeff Lelko

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Jeff, mate you've given me renewed inspiration! I'll head down to the shed now and attack it with renewed vigour. I did swap out the main elec circuitboard in the base with a known good one, so presumably if I go upstream further and swap out the transformer maybe, and a few other things earlier in the chain, I'll find the fault there? Tbc..!

Great!  Glad my attempts at words of wisdom are useful!  Yeah, keep working at it.  Honestly, it still sounds like a motor issue to me, especially if you've already swapped the driver board.  Are you sure the new tilt motor is known to be working?  Though unlikely, there could be an issue in the wiring harness.  I say unlikely because these problems usually manifest in dead components - not weak ones.  If you can (and before you start really pulling the unit apart), I'd suggest trying to jumper the good unit to the bad one - i.e. unplug the wires going to the "good" tilt motor and plug it into the motor on the "bad" tilt unit.  Doing so will rule out the motor, pulley, belt, and any other peripherals.  Just be sure to unplug the pan motor before powering up the unit, otherwise it'll try to pull the harness out during calibration.  If that's successful, try the same thing but at the PCB side of the harness.  That'll rule out the wiring and connectors.  After that, it's the PCB and power supply...but having only one bad attribute makes me still think it's the motor.  Troubleshooting moving lights can be frustrating, but don't give up!  Keep us posted! 
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Stuart Murphy

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Great!  Glad my attempts at words of wisdom are useful!  Yeah, keep working at it.  Honestly, it still sounds like a motor issue to me, especially if you've already swapped the driver board.  Are you sure the new tilt motor is known to be working?  Though unlikely, there could be an issue in the wiring harness.  I say unlikely because these problems usually manifest in dead components - not weak ones.  If you can (and before you start really pulling the unit apart), I'd suggest trying to jumper the good unit to the bad one - i.e. unplug the wires going to the "good" tilt motor and plug it into the motor on the "bad" tilt unit.  Doing so will rule out the motor, pulley, belt, and any other peripherals.  Just be sure to unplug the pan motor before powering up the unit, otherwise it'll try to pull the harness out during calibration.  If that's successful, try the same thing but at the PCB side of the harness.  That'll rule out the wiring and connectors.  After that, it's the PCB and power supply...but having only one bad attribute makes me still think it's the motor.  Troubleshooting moving lights can be frustrating, but don't give up!  Keep us posted!

Thanks mate. Yes, I'm sure the tilt motor's okay.. I swapped it with the other light which has no tilt issues, so I figure it's fine? Same for the main PCB boards.. swapped those from the good machine to the bad one, and no change - there's a small pcb board in the head, and a large one in the base - I swapped both out and no change. The only thing I haven't done is swapped out the main power transformer, but it couldn't be that - right?!
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TJ (Tom) Cornish

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Thanks mate. Yes, I'm sure the tilt motor's okay.. I swapped it with the other light which has no tilt issues, so I figure it's fine? Same for the main PCB boards.. swapped those from the good machine to the bad one, and no change - there's a small pcb board in the head, and a large one in the base - I swapped both out and no change. The only thing I haven't done is swapped out the main power transformer, but it couldn't be that - right?!
Is the tilt belt-drive?  If so, is the belt slipping?
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Jeff Lelko

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The only thing I haven't done is swapped out the main power transformer, but it couldn't be that - right?!

I doubt it.  I'm with TJ on this one - if you're confident the motor is fine I'm betting it's a loose pulley.  With a good multimeter or preferably an oscilloscope you can do much better diagnostics on the electronics, but if everything else is fine and the problem hasn't gone away after swapping PCBs I don't think there's much to discover.  I remember you saying that you swapped the belt, but how about the pulley?  There will be one or two set screws holding the pulley on the motor shaft.  Make sure that when the motor turns the pulley isn't slipping.  I've had a case where everything looked fine but a small crack in the pulley was causing intermittent slipping both between the shaft and the pulley and the pulley and the belt.  Luckily pulleys are a cheap fix, so let's hope that's the case!  Also, check the pulley on the other end of the belt.  With the fixture powered up, gently tilt the head up and down with your hand - unless the shaft of the motor is turning there's something slipping somewhere.  Good luck!
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Stuart Murphy

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Is the tilt belt-drive?  If so, is the belt slipping?

Hey Tom,

Yes, it is a belt drive tilt.. I have the plastic covers off so I can see everything, and the belt doesn't appear to be slipping at all.. I've also swapped belts with the other good fixture, and the problem remains. It's got me beat. Other than swapping out the main unit transformer, I have nothing left to try that I can think of, and I didn't think that would be the problem, but maybe it is. Swapping it out is a bit of a chore, so I was hoping not to have to!
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Stuart Murphy

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I doubt it.  I'm with TJ on this one - if you're confident the motor is fine I'm betting it's a loose pulley. With the fixture powered up, gently tilt the head up and down with your hand - unless the shaft of the motor is turning there's something slipping somewhere.  Good luck!

Thanks Jeff. I've done as you said with the fixture powered up, and tilting the head by hand. All the pulleys seem to be locked perfectly and the motor shaft turns with them as I tilt it, so I can only presume it's in fact a weak motor as you suggested all along. I definitely swapped it out for the good motor from the other fixture, which didn't help, but maybe I did something dumb like not tensioning the springs correctly or something. I dunno. Both units seem completely identical in and around the pulley, motor and belt. So I think I'm going to turn my attention to the sole good one, which only has those alignment problems I mentioned earlier with both the color and gobo wheels. They might be stuffed motors too, but weird that all 4 in both fixtures are out of alignment. Thanks for all your help.. I'm getting close to conceding defeat on this occasion. :-|
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Jeff Lelko

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I'm getting close to conceding defeat on this occasion. :-|

Yeah...it's frustrating not to see any results.  Short of plugging the two heads together as described further up to definitely rule out the motor/belt/pulley this is where I'd be pulling out my oscilloscope to see what's going on with the power/logic side of things.  Sorry that I can't offer any other suggestions!  Sometimes fixtures just reach end of life where they then become parts donors to other fixtures.  Best of luck with this though!
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Stuart Murphy

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Yeah...it's frustrating not to see any results.  Short of plugging the two heads together as described further up to definitely rule out the motor/belt/pulley this is where I'd be pulling out my oscilloscope to see what's going on with the power/logic side of things.  Sorry that I can't offer any other suggestions!  Sometimes fixtures just reach end of life where they then become parts donors to other fixtures.  Best of luck with this though!

That reminds me mate.. on my fixture, the tilt motor wiring harness is located right next to the tilt motor itself, which is in the spinning vertical arm of the head. Whenever I switch the unit on, of course the head spins right away. So won't that just rip the donated tilt cable straight out? Sorry for such a stupid question, but in that scenario, it seems I'll end up with chards of splintered wiring loom flying about the room..! :-D
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Jeff Lelko

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That reminds me mate.. on my fixture, the tilt motor wiring harness is located right next to the tilt motor itself, which is in the spinning vertical arm of the head. Whenever I switch the unit on, of course the head spins right away. So won't that just rip the donated tilt cable straight out? Sorry for such a stupid question, but in that scenario, it seems I'll end up with chards of splintered wiring loom flying about the room..! :-D

You're absolutely right, which is why I also said in my original post with that suggestion to unplug the pan motor first, otherwise you'll definitely end up with wire spaghetti and possibly more damage than when you started :)
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ProSoundWeb Community

Re: Gobo and Color Wheel Alignment Issues on my ACME iMove 8S Moving Head Spots
« Reply #15 on: March 30, 2019, 02:01:59 pm »


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