When scrollers go bad...

[sk8rsdad]

Last night during first tech, a gel string in one of our Chroma-Q scrollers failed catastrophically, tearing the metal tab off the end and flinging it to the stage floor, much to the alarm of huddled mass of actors below. The scroller continued to spin until power was killed to the string. If it had to happen, it was best that it happened in rehearsal.

Gel strings warp and distort over time due to heat stress and mechanical wear. Chroma-Q scrollers rely on gel string tension as a feedback mechanism. Consequently, when the scrollers start to through end-to-end resets that can't be resolved by re-tensioning the string, you know it is time to replace the string. This particular gel string was exhibiting that behavior for the past week, and was due to be replaced when our inventory gets replenished next week.

When the unit failed, the constant flapping was a nuisance that could only be fixed was by killing power to the entire string until the electric could be flown in so the scroller could be de-energized and bypassed. Does any manufacturer provide the capability of shutting off the scroller drive motors remotely, or perhaps make use of the loss of tension to shut down the drive motors automatically?

It occurs to me that there must be a lot of lore around scroller troubleshooting, failure modes, and quirks of specific units. Does anybody else have a scroller fail anecdote to share?

 

[Kelite]

When the unit failed, the constant flapping was a nuisance that could only be fixed was by killing power to the entire string until the electric could be flown in so the scroller could be de-energized and bypassed. Does any manufacturer provide the capability of shutting off the scroller drive motors remotely, or perhaps make use of the loss of tension to shut down the drive motors automatically?

Yes-

The color scroller product line Apollo had sold over the years also used spring-tension for the gelstring. The scenario you've described was the main reason we designed the Smart Color with two motors, working against each other for proper gelstring tensioning. The scrollers are much quieter, as the sound produced (especially at higher speeds) by the take-up-reels has been eliminated.

There is also a remote reset function within the Smart Color-

Page 7 simply explains this feature - http://downloads.goapollo.com/Smart Color PRO Family Manual.pdf

Fortunately no one was hit with the flying metal clip when your Chroma Q string let go, as this little projectile has the ability to fly quite some distance-

 

[Kelite]

This was mentioned by our electrical engineer, and offers some design insight as well:


With respect to a broken gel string resulting in a free-wheeling scroller howling like a screaming banshee-

There is an embedded software failsafe feature in the Smart Color Pro that provides a shutdown mode. If the gel string breaks, the motors will spin for less than 20 seconds, then the unit will shut down, and the display will flash "Err". This way you don't have that annoying howling effect, kind of like playing cards in your bicycle wheels. This feature will also trip if you power the scroller up without any gel string installed... you will see the hubs spin for less than 10 seconds... then they will stop and the display will flash "Err". That way nobody stubs their fingers on those spinning metal hubs- that would hurt!

If the technician activated the "remote reset" function the unit will go through a "power on reset sequence" and try to do an end-to-end calibration. This remote reset feature can clear a dropped or tangled gel. This also works well if the gel is getting warped and there are some marginal accuracy problems. If the gel is torn or broken and you activate the "remote reset", it will free spin for a few seconds again, then it will still shut down again.

 

[MuseumGuy]

I think the biggest scroller fail was when we found out the CXi-IT units aren't backward compatible with the regular CXis. Epic $$$ fail.

 

[Sean]

Did someone lead you to believe otherwise?

 

[kicknargel]

In one of my first scroller experiences, I had the units lit for a while without powering up the scrollers (for work light). The when it was time for channel check I ran the scrollers to full, but having been lit without the fans running, the backside of the tape holding the sting to the reel glued itself to the gel on top of it. About 8 strings tore simultaneously and catastrophically, and I about jumped out of my shoes.

This was long, long ago.

 

[GageStryker]

I"m running a house that's 100% Apollo Smart Colors now, and I am so happy. They've been great, honestly - the only scroller I've ever hung in a place where access was a problem. And they self-tension on reset - makes me so happy.

I have had some fun problems. My favorite was a ChromaQ that was fourth in a string of 6 that would just magically reset (at full speed) at random. Replaced the scroller with a different unit, still the same problem. Didn't affect scrollers 5 and 6 in the string. Replaced the power supply, and now it's unit #6 that's acting up... there's some scroller ghosts in that venue.

My best scroller going bad experience was a chroma-Q that went ape and I used a band saw, gel frame, and some PVC pipe and foam to make a quite effective, quite silent projector dowser.

And then the projector got cut from the show...

I think the post still lives here somewhere, though.

 

[Lotos]

I have had some fun problems. My favorite was a ChromaQ that was fourth in a string of 6 that would just magically reset (at full speed) at random. Replaced the scroller with a different unit, still the same problem. Didn't affect scrollers 5 and 6 in the string. Replaced the power supply, and now it's unit #6 that's acting up... there's some scroller ghosts in that venue.

If memory serves, most Chroma-Q PSU's (if not all) only provide enough power to allow you to use four scollers on a single send/return loop... More *will* work *most* of the time... And I think you're seeing the nasty effects of too many scrollers not enough power on the loop.

My personal choice are Chroma-Q branded scrollers... Nothing against Apollo or Wybron... As I've used both brands over the years, and have respect for them.
Chroma-Q simply work for me, I know their little nuances, and can do most of the repairs myself these days.
I've thankfully never had gel tabs flying across the stage, though we tape our takeup reels with white artists tape, which would prevent just such an occurance (A hold over from the days when the takeup reels had no slot for the metal tab).
The newer Chroma-Q models cease spinning when they lose tension due to a tear, or any other reason... The older models though, yeah, make a hulluva racket... I try and keep the older units back as spares these days, but I've got some Chroma-Q's from the early 90's still going strong, year after year.

Worst experience? Tired electrician... Scroller met the deck from some 20ft up... Arguably not the scrollers fault, but made for some serious scroller fail... It still worked, just not as expected... And needed $100 of TLC at the shop...