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Electronic Theatre Controls Inc

Unison Low Voltage Errors


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 showing Dimmer Error: Low Voltage

Description/Explanation of Issue

This can be caused by several different issues.

  • Incoming phase voltages are low
  • -5V voltage regulator on dimming engine board has failed
  • Opto-isolator(s) on dimming engine board has/have failed
  • Volt-sense phase signal line on dimming engine board is calibrated low, either due to failing opto-isolators, failing calibration potentiometer, or a failing op-amp



  1. Check the incoming phase voltages
  2. If the incoming phase voltages are OK, please contact ETC or your dealer for repair options


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