Automated Fixtures spare Vari-Lite VL3500 pan issue, off by 3°

[TreborK]

So the other day I replace one of our VL3500 spots with a spare, the original light was having variable issues through many shows & replacing it was a last resort. After hanging the new unit I noticed that the pan was off center, I tried re-homing it but it was still off by about three degrees which is about a foot or two difference on stage. I'm totally familiar with the ins & outs of this light & I was wondering if there is a way to adjust the pan calibration on the light itself. This would be the best solution so I don't have to edit the show file directly.

If not the next option is to edit the show file on the theater's ETC Ion. I'm familiar with the basics of this console but I'm not sure if there's a better way to address the issue aside from editing each cue the light is used in. My main question is, is there a way on the console to update the pan home, or a way to add three degrees to the moving light's pan in all the cues it's used in on top of the current values. I was told there was a way to update the focus pallet which might solve this issue, but I'm not sure if all three of the moving lights use the same pallet.

I hope there is a simple solution to this headache of a problem, I'd rather not have to add three degrees to the 70+ cues in the show that the light is used in.

Thanks in advance!

 

[TJCornish]

Isn't this what position pallates are for? I'm a novice mover guy, but I own a pair of VL770s and they don't have absolute value pairity between units for things like focus, etc. According to the VL tech I talked to, this was by design, and within manufacturing tolerance. Not sure if that applies to pan or tilt.

 

[derekleffew]

TreborK, adjusting the pan offset, whether on the console or in the light, is only a temporary fix. If it drifted once, there's no guarantee it won't drift again. Don't put a band-aid on it, fix the problem. That being said, I believe you'll need to edit the fixture personality. Adding a pan offset to the default home position (usually 50/50) may be a quick fix. Editing every focus position palette will certainly "fix" it, until it drifts again.

 

[rochem]

TreborK, adjusting the pan offset, whether on the console or in the light, is only a temporary fix. If it drifted once, there's no guarantee it won't drift again. Don't put a band-aid on it, fix the problem. That being said, I believe you'll need to edit the fixture personality. Adding a pan offset to the default home position (usually 50/50) may be a quick fix. Editing every focus position palette will certainly "fix" it, until it drifts again.

Agreed, fixing the show file is a quick fix, but shouldn't be relied upon, as the light may drift again. Also, it's possible that the fixture may not be off by 3 degrees throughout it's whole range of motion - I have seen problems like this where the error was variable by a few degrees depending on where the fixture was currently pointing. However, a quick fix in the console is to edit the fixture personality to make the console go to +3 instead of 0 (50) for the home position. Make sure you duplicate the fixture personality and edit this duplication instead of making the change to all the 3500s in the show.

 

[xander]

Changing the fixture's home value will not fix anything. You will need to update all of the palettes and/or presets that use the fixture to have it be accurate in all the cues. The home value of a fixture in the ION library is just a point in the pan/tilt range that the fixture starts at and goes to when you hit the HOME button. It will not affect any recorded values.

-Tim

 

[rochem]

Changing the fixture's home value will not fix anything. You will need to update all of the palettes and/or presets that use the fixture to have it be accurate in all the cues. The home value of a fixture in the ION library is just a point in the pan/tilt range that the fixture starts at and goes to when you hit the HOME button. It will not affect any recorded values.

Subtle but important difference. Changing the Home value is something that I do on almost every show, and all it does is have the fixture go somewhere other than 50/50 when the board tells it to go Home. You're correct, that would not help at all. What we're suggesting is editing the fixture personality itself. In the fixture personality is something that says "when you tell the Pan to go to Zero, I'm going to send a value of 32768 (half of [255+1]^2) to the fixture". He would be changing this value, which would (theoretically, assuming the drift was constant throughout the whole range of motion) alter every position that the light would go to. I've made changes like this when I needed a different level of functionality out of a fixture, or when a fixture profile was inaccurate/not available, but never in this instance, however it would theoretically work.

 

[rochem]

But, having said that, if I were in this situation, that would not be an option I would use. If I could possibly get my hands on a spare unit, that's obviously the best solution. If it's rental gear, the shop will be very willing to send you another fixture, and if they're owned by you, hopefully you have some parts on hand or can get access to them. If fixing the fixture itself absolutely wasn't an option, I would just update each preset. With a good workflow, it really shouldn't take you more than ten or fifteen minutes to fix presets for one fixture on even the largest shows. Especially since you're just fixing one single attribute, and the iris/zoom/shutters/everything else will be the same, you just need to move one encoder and you're set. If it's a long running show, hopefully you have a record of where each preset is supposed to be, so this should be quick work.

 

[xander]

I know that you are talking about editing the fixture library.

However, a quick fix in the console is to edit the fixture personality to make the console go to +3 instead of 0 (50) for the home position.

This is what I was talking about. And this statement is just not true. All you would change was the home value.

Yes I suppose you probably could change the user values in the pan ranges for the fixture personality and get a universal shift of everything in the show, but that is not what you were originally saying. Either way, I would not opt to use this method, but would update the palettes/presets as it is much cleaner and apt to be correct across all cues.

-Tim

 

[rossgrahamdesign]

Have you tried all the typical trouble shooting solutions? I had a fixture do this a few weeks ago and I simple did a hard reset and it fixed it. I would reset to factory setting, look at the sensor maybe blow some air on it. look at the switch that triggers the limit for the pan.

If the show was programmed will on ION then updating P/T palettes should take that long... if you have a show of raw data that's not referencing palettes then forget it. it'll take forever.

 

[chawalang]

As far as repair, take the base plate off, it should be 4 allen screws. Once that is off give the pan belt a little tug see if it has good tension. If it doesn't seem tight it may be a worn out pan belt. If that seems good I would take an alcohol swab and clean the sensor and the think plate on the motor that passes through the sensor. It sounds like a pan belt or pan issue sensor issues, if its the belt good luck, you'll see what Im talking about when you take the plate off. If you've never replaced it before it'll take you about an hour the first time. there a lot of cables you need to pull out through the center to replace it and no disconnect's there.

 

[phenry]

I spoke with the VL guys and they suggested:
Make sure the software in all the fixtures is the same version.
Make sure they are all set to the same pan/tilt speed setting.
Could be a loose belt.
Could be a bad or improperly reassembled pan mechanism or encoder.

Check these things to your comfort level. If it is a rental fixture, check with who you rented it from first.