[SML] Twitchy Forerunner all a-twitter

[Mike Voytko]

Hi Jon, 

In my experience this is a loose or deformed drive belt (the round, clear one inside the motor housing).

A number of mine developed this issue, more or less all at once after about 10 years of use. 
Replacing the belts (and cleaning the accumulated gunk off the pulleys while you’re in there) resolves the issue.

I’ve seen dislodged gel-adjust pots too, but the symptoms on those tend to be more dramatic IIRC.

https://www.wybron-scroller-parts.com has the belts, as well as a how-to on swapping them.

HTH,
Mike V.
—
Mike Voytko
Lighting & Sound Supervisor
Tisch School of the Arts / Theatrical Production
New York University 
mv35 at nyu.edu
AMC Info: http://www.nyu.edu/amc





> On May 8, 2019, at 11:08 AM, Jon Ares via Stagecraft <stagecraft at theatrical.net> wrote:
> 
> Hi folks... I've got a 7.5 inch Wybron Forerunner that's giving me
> fits - changed out the gel strings on our units recently,and one is
> twitchy - and getting worse. I unloaded the string, and thought maybe
> I over-tensioned it or something, and in trying to re-load the string,
> it's inconsolable with its twitching.  If I fiddle with the "adjust
> gel" trim pot, I can get it to calm down, but the moment I touch a
> spring roller, it goes back into twitch mode.  I've tried different
> cables, power supply, termination, etc.... all the other scrollers are
> fine, as well.
> 
> I could get replacement parts, but I don't know what part to get...
> new control board? New gel adjust pot?
> 
> I've got to keep these things running another few years....
> 
> -- 
> Jon Ares
> https://urldefense.proofpoint.com/v2/url?u=http-3A__www.arescreative.com&d=DwICAg&c=slrrB7dE8n7gBJbeO0g-IQ&r=p68ZjE_TEWbVZPpMfL6ykQ&m=2CqFuBrRaxZRCY13UZZc_VlHoy6X146EtznuYpeI-Hk&s=42_-UaciG-tyt7ZPS32rPqk6qdQybpabosTshrKe-gg&e=
> 
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