Skip to main content
Electronic Theatre Controls Inc

Expression 3 SMPTE Events Don't Play When Moved to Later Time

You can run into a problem with SMPTE events in an Expression 3 where if you play an event, then change it to a later point in time it may not play the second time.

Here is why...

  1. The entire SMPTE screen is buffered information - so that you can run your show and edit it at the same time. The new changes won't take effect until the event is recorded, sorted and the event pointer is reset. To record and sort the new information, you have to either leave SMPTE mode or press the SORT key. Now any changes that are in events NOT YET RUN, will be there when that event is run.
    • You can cycle the power on the console
    • You can reset the internal clock
    • You can press LEARN twice (taking it out of learn mode resets everything, including the sort).
  2. If you made a change in an event that you ran already, you have to reset the pointer to get that event to run again. There are several ways to do this. 

Try this and see if the problem disappears.

  • Another thing that can cause problems is synchronizing the clocks. A SMPTE signal tends to be noisy and frames are frequently missed, so that if you run on just the external clock, things can be missed. That's why there is an internal clock - running both clocks together allows the console to fill in the time gaps with the internal clock.  If it detects missed frames, it will run the events that got skipped. There is about a 5 second period needed to get the clocks synced up once they are both present. To be safe, both should be up and running at least 10 seconds before you expect an event to run. 

There is a complicated sync up procedure when the two clocks differ by more than a couple of frames. If you reset the external clock, the internal clock will follow it once the sync is completed and keeps everything running smoothly. It's important to know that you need BOTH clocks enabled for best performance.


  • Was this article helpful?