CEM Blank Green Screen

I have a Sensor 48 touring rack I permanently installed new in 2003.  A month ago  all circuits connected to the rack started coming on to 50% intensity at 12% level on the console.  As you increase the level on the fader to full, from 12%, the intensity of the unit goes to full as well.  When you fade out from full level on console the unit will fade from full intensity to 50% intensity until it gets to 12% level on console where it goes to 0% intensity.

I went to the Sensor rack and noticed the door light was flashing then looked for the error message on the CEM and noticed that it is blank and has no text on it. I have an ION Console and an Express 72/144 connected to a merge unit.  Merge unit is connected to a 1 in 5 out splitter connected to a  Colortran D192 Dimmer Rack, the Sensor 48 Rack as well as multiple Leviton 4 X 575W packs.  The Sensor Rack is the only dimmers reacting this way even when by passing the merge and splitter units and going direct from console to Sensor Rack.

I started to notice the problem after the power to the building was shut down in order to connect power to a new building on campus.

I assume the CEM is bad due to the blank screen.  Unless there is something I am missing.  Any help or advice would be greatly appreciated. 



  • Hello Ray,

    The first thing I would do is give the CEM a good clean to eliminate any dust/junk that might be in there. Power off the rack and remove the CEM; then with a can of compressed air and a soft paintbrush, remove any dust or debris inside of it (they do tend to get dusty due to the constant airflow). As you do this be careful not to put too much force on any components or adjustment pots inside it.

    There are also some fuses inside - what you describe doesn't sound like it'd be caused by a blown fuse, but worth checking them all with a multimeter.

    If it still isn't working after that, it probably needs repair. Your nearest ETC dealer should easily be able to arrange a repair for you, and can help arrange a loaner unit if you need one to cover shows.

    Hope that helps,


  • Thanks for the fast response, Tom.  I forgot to mention that I had read the forum prior to sending the question and saw all the airflow/flickering issues and cleaned the entire rack, CEM, Dimmers, Fan and Filter.  I did ring out the fuses in the CEM, like you said, and they were all good.  I will call Lite-trol out here and see about a repair.

    Thanks again