Bump in power surge

[Pan]

Hey there,

One of my jobs is as a trainee in an independant theatre. My 'trainer' has left and I'm now on my own to educate myself and problem solve in the theatre. We hire the theatre to different production companies and have in house companies that run their own productions in the space as well.
Today an outside hirer was bumping in and we encountered some problems with the power and dimmers talking to the desk. There are two dimmers daisy chained together and run from seperate 3phase power sources. We set the lights up in the rig and made sure that the desk and dimmers were talking to one another before we headed out for lunch. When we came back the power had tripped. The switches on the back of the dimmer had flicked and the circuit breakers in the theatre had flicked as well. We double checked that we hadnt overloaded any of the patches and then turned the power back on. We then reset everything on the dimmers and on the desk (an ETC Express) and .... nothing happened. Checked the DMX running from the desk to the dimmers and the DMX daisy chaining them with a multimeter, they were fine. Plugged everything back in. Turned everything off and back on. Off and on. Off and on. Three times - then our lights responded. Can anyone guess at why it is that we had to turn the system off and on and reset the dimmers 3 times before there was a response?

Cheers.
Yours in confusion-
P.

 

[Chris15]

What model of dimmer?

 

[Pan]

They are Jands FP12 Channel digital dimmer racks.

 

[David Ashton]

the problem lies in the racks, I have had similar issues with them, talk to Jands or your supplier.

 

[JD]

There are two dimmers daisy chained together and run from seperate 3phase power sources

These two power sources, are they in the same physical location and do they share a common ground? Although the building will have one ground point at service entrance, sometimes if ground paths take wildly separate routs, you can inadvertently create a very large loop antenna via the DMX line. The results of that can be very unpredictable!

 

[Pan]

Thanks David. It's good (in a very ungood kind of way) to know that others have had similar problems with the equipment. I shall call my supplier and/or Jans and trouble them with my extensive list of dimmer woes. Bwa ha ha!
JD, the power sources are in the same location and share a common ground. Problems with haywire DMX have occured in that particular venue once previously before in my time there.

 

[David Ashton]

well one of them died on me from a new installation by another company, I took it back to them but the next morning it worked fine so I took it back to the school where it worked for weeks but occasionally stopped, switching it off and on makes it work but it doesn't do a lot for your confidence.DAE had some dealing with the same problem, I'll get Don to advise.

 

[DAE]

There was a problem with an early batch of Jands FPX dimmers. The ribbon cable between the main pcb and the traic module was not crimped properly. The dimmer would lock up, there was usually an odd display and no activity on the display.

Jands are repairing these dimmers under warranty through their service agents. There was not a large number affected.

There is no software or hardware reset on these dimmers so if they are locking up, it will be the fine pitch ribbon cable.

Hope that helps you.
http://www1.jands.com.au/__data/assets/pdf_file/0015/6810/FPX_Dimmer_Rack_Mount_Operating_Manual.pdf
The manual can be downloaded from the Jands website

 

[JD]

The switches on the back of the dimmer had flicked and the circuit breakers in the theatre had flicked as well.

This line is the Wildcard! No matter what happened on the DMX or control end, the fact that the dimmer’s breakers tripped as WELL as the theater’s distro is puzzling. Even if you sit there and bump every light from off to full at the same time, you shouldn’t be tripping breakers, let alone in the theater! The only time I ever had that happen was when a PECO transformer failed, and we apparently got a nice jolt of primary. Anything else in the theater show any sign of trouble? Is the stage run off a different service than the rest of the theater?

 

[Pan]

Hey there,
Thanks David and DAE it helps a lot to know that.
JD - The stage is run off a different service and we had no issues anywhere in the rest of the theatre.