CCT regal 6 dimmer issue

[the grumpy one]

Bit of an odd one. I just wondered if anyone else has had this issue.

 

We have 4 CCT regal 6 DMX dimmers in our small studio theatre. On Saturday, whist we were shut, we had several local power dropouts and spikes. Some one had not followed procedure and turned the dimmer power off. They had turned the lighting board off. The fire alarms went off on Sunday. The key holder came in to find the whole 18K rig on full and the studio temprature had gone up above 50C. They just un-patched everything from the dimmers. When I came to investigate, I found that all the dimmers were still outputting 100%. I turned on the lighting board. But this did not take control of the dimmers. I turned the dimmer power off and all returned to normal.

 

Has anyone else ever had this issue? Would it happen with modern dimmers?

 

It is a bit worrying that a mains spike can open the thyristors to full and hold them open until power is turned off.

[timsabre]

Sounds like the microprocessors in the DMX decoder element of the dimmers had crashed (assuming that's internal to the dimmers - or the demux if not).Unfortunately power spikes can do funny things. You are probably lucky that it all worked again normally after a power cycle, I have experienced various types of destruction caused by power faults.

 

[ianknight]

The CCT Regal 6 is a "rebadged" Zero88 BetaPack 1 - the internals are the same but a different colour paint finish and legending.

 

As such, they're fairly reliable (I don't believe CCT reworked any of the electronics) so it was probably something as simple as a crash of the PIC on the DMX board or just a large enough power spike induced on the data lines that got mis-interpeted by the DMX interface. It would be worth popping the back cover off each dimmer to check the main PCB isn't damaged or showing signs of burning (yeah - they're so durable they'll work for a while when damaged!) or get someone who knows the inside of Zero88 kit to do it for you.