No Power to Echo Architectural Control Processor in DRd

Issue

Blank screen on the Architectural Control Processor, no LEDs to the left of the screen.

Explanation

This means the Architectural Control Processor (ACP) at the bottom of your DRd has no power. If the rack was working before, the first question to ask is if there was recently a power event. Power events can negatively affect different parts of the rack.

The ACP receives power from the Dimming Engine module at the top of the DRd rack. the Dimming Engine receives either 120v or 277v incoming power to the rack.

1. First, make sure the ACP is firmly seated in the rack. It slides in, so just push it to ensure a good connection.
2. Second, fully power down the rack for a minute then reapply power to see if anything comes back.
3. Third, flip the dimming engine into TEST mode using the test switch on that module.
   1. If all of the signal lights on the rack and all of the lights in the actual space come on, the dimming engine still has power. One of three scenarios could be the problem. Usually either of the first two is the issue. It's rare for the ACP itself to be dead.
      1. A connection between the dimming engine and the ACP is bad (such as the ribbon cable, signal distribution card, or right I/O.
      2. The dimming engine may not be passing the 24vdc to the ACP and it needs to be repaired.
      3. The ACP itself is dead.
   2. If no lights come on, the dimming module is dead and might need repair.
      1. 120v dimming engines have a removable 1.25 Amp fuse that can be checked on the left side of the unit next to the power harness connection. If this fuse is blown the dimming engine will not function. A spare is located next to it.
      2. 277v dimming engines have three fuses next to the power harness connection, but are soldered onto the PCB and require being sent in for repair if any of these fuses are blown.
4. To fully determine if the dimming engine is dead or incoming power to the rack is bad, look at the optional Station Power Module (SPM) that would live above the ACP. It gets the same incoming power as the dimming engine. If the SPM's LEDs are on, the dimming engine needs repair. If the SPM's LEDs are off and the TEST option does not work, have an electrician check incoming power to the rack.