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Electronic Theatre Controls Inc

Expression 2, 2x and 3 LED Guide

The Expression 2/3 line of consoles has three or four primary sets of LEDs.   The first set is on the facepanel, the second set is near the Ethernet and Echelon chips on the main CPU and the third set is located in the far left hand corner just below the CRT #2 connector on the Universal console and the far right below DMX out connectors on the pre-Universal consoles.  The fourth set is on the Encoder board on Expression 3.


Indicates communications between the Facepanel and the main CPU

  • Red LED blinks steadily (~1 Hz) - FP CPU is running.
  • Green LED blinks very rapidly (appears to be on constantly) - FP CPU is transmitting data (button hits, pot levels, etc.) to the main CPU.
  • Yellow LED blinks at the same rate as the green LED - CPU is sending data to the facepanel regarding the status of the LEDs in the various pots, buttons, and windows.

Location of Facepanel LEDs:
Top right hand corner of the Facepanel PCB as you open the console.


Eight (8) LEDs on the main CPU.  All are red. (Only two of them are used)

  • 1st LED blinks whenever the system clock is running.  It will pause during boot, but otherwise should be blinking steadily at all times (~1-2hz).
  • 2nd LED indicates when the console code is running.  It can be somewhat erratic but generally blinks faster than the first LED. If #1 is blinking and #2 is not, either:
  • The console is doing something expensive in terms of processing; the console could just be hung. If both LEDs have stopped: The console has crashed.

Location of Processor LED's (Universal CPU):
Two rows of four LEDs are located below and slightly to the left of the CRT#2 connector

  • System clock LED-CR14
  • Console code LED-CR12

Location of Processor LED's (Pre-Universal CPU):
A line of eight LEDs is located on the right side of the PCB near the top

  • System clock LED-CR17
  • Console code LED-CR18


Indicates Ethernet UTP communication only (no ThinNet or AUI) Red LED (LED) indicates a number of things:

  • On solid = normal
  • 1 blink = link down
  • 2 blinks = jabber
  • 5 blinks = polarity reversed
  • 1st Green LED (led) is the transmit LED.  On when the console is talking to other devices on the UTP line. 
  • 2nd Green LED (led) is the receive LED.  On when other devices are transmitting to the console.
  • Yellow LED (led)  - On only when there is a collision on the UTP line.

Location of Ethernet LEDs:
The LEDs are located on the left hand side, towards the rear of the CPU card on all consoles.  The screened board locations change with the processor type.

Processor type: EXPN Universal CPU

  • LED-red-CR9
  • LED-green-CR10
  • LED-green-CR16
  • LED-yellow-CR17

Processor type: EXP 2X pre-Universal CPU
(all revs)

  • LED-red-CR1
  • LED-green-CR2
  • LED-green-CR3
  • LED-yellow-CR4

ENCODER LEDS: Five LEDs on the Encoder board

  • CR 10/14- Green- +5vdc
  • CR 11/15- Red- Not Used
  • CR 12/16- Amber- PIC Heartbeat
  • CR 13/17- Amber- Mouse Communication
  • CR 14/18- Green (Dim)- Send/Receive to Main  
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