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Electronic Theatre Controls Inc

CPU 01, 02, or 03 Fail on Unison DR racks



The information in this post is provided to assist in troubleshooting. Perform work at your own risk. ENSURE ANY POWER FROM DEVICES HAS BEEN DISCONNECTED BEFORE SERVICING ANY EQUIPMENT. If you do not feel comfortable performing the work, please contact us or your local service center. Be aware that ETC and its Affiliates are not responsible for any damage or injury caused by service of our products by anyone other than us or our authorized service providers, and such damage is excluded from the product’s warranty.


Unison processor is displaying a CPU Error. Overlay LED will be continually blinking


There are several causes for this error:

  • One or more of the incoming phases is bad and is causing the phase processor(s) to throw an error
  • One or more of the processors monitoring each phase has failed
  • One or more of the opto-isolators for monitoring the phase voltages has failed

It is entirely possible that this is normal operation due to timing issues at the firmware level. The error should normally clear within about a minute. In systems where the power phases are dirtier than normal, this error may persist a little longer.

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