Spontanious Fade to Black

I have crashed an Express with a Motorola walkie-talkie, so I believe your report.  We'll have to wait for a factory post, but I seem to remember that there is a retrofit that greatly reduces the problem.  Until then, I would avoid having a cellphone near the board.  It's no surprise that the cellphone bothers the headsets, so why did he/she have it turned on, especially FOH?  Can you set the dimmer rack to hold levels on loss for five minutes, just in case?  There should be no problem rebooting the board in that amount of time.

Timothy:   

Thank you for the response.  The other possibility is a power spike of some sort, the board is powered through a PC grade UPS but there are better systems available.  Saturday night we banned cell phones from anywhere near the light loft and experienced no issues.   A walkie-talkie can put out a much as 5-watts, the typical cell phone is about 300 miliwatts so its still a bit of a mystry to me. 

Bill

I will add that I have personal experience where a cell phone, placed on top of a fire alarm panel and receiving an incoming call, set the alarms a ringing and a flashing and all sorts of things that I’m glad it was a service call, and not a show call.   I can hear through my car radio whenever my cell is logging in/out of a tower.  I have been told stories of large (200A+) GFI’s having to be caged in grounded chicken wire to stop nuisance tripping from radios and cells. 

 

That said, I wonder if grounding the console (you could use the “strain relief”) wouldn’t help.  I don’t think it would hurt, but I don’t know if the ETCLink and the RFU are grounded to chassis or not. You dont want them creating ground loops.  I actually don’t know if Vcom from the PSU is grounded or not.  I believe the DMX outs are isolated…but I don’t know. <<<insert ETC's response here>>>

 

You ARE grounding the AC In, right???

The real issue here is not only the amount of power a wireless device emits but also what frequency.  Due to these wide variables it is indeed difficult to design around all the possible intereference types that can cause harm.

I can tell you from experience that it is not wise to leave a cell phone or 2-way radio near an Express console.  If it is my show, I leave my cell phone in my hip holster no matter what console it is as I do not wish to have an issue.  Bruce's examples (Hi Bruce) are spot on and real.  We have spent a lot of time over the years trying to make the gear more resilient to external interference and later model Express consoles are much better than the first versions when it comes to this.

Still, keep the phone away, it most likely did cause the problem.  Sorry I can't make it better for you but do remember that this type of interefernce is exponential so if you move it away twice as far the interference is four times less powerful (hence the hip mount).

SeaQuest DSV called years ago about subs flickering on their Insight 2x (also called the Illuminator 3000 when it starred as an underwater monster killer in one episode).  It was intermittant but occurred shortly after I overheard someone asking over a radio to bring up some channels.  "See, it did it just then!"  "Where is your radio?"  "On the subs."

Thought'd you like a fun story....

David North

ETC Technical Service Manager

To Everyone Who Responded.

 Thank you, valuable lesson.  I just don't want it to happen again and the advise here will prevent that.  We are a volunteer organization and the offending cell phone was for a person who was on call.  Cell phones  have become a necessary evil in our culture and we need to find a way to live with them. 

 

WTC Bill,

Yakima, Washington