Engine control unit/power system The engine control unit (ECU) coordinates all print engine activities, drives the laser, and coordinates print data from the formatter with the image formation process. The ECU also includes power supply and distribution circuitry. Note In several other HP LaserJet products, the ECU is also known as the controller PCA or the DC controller PCA. The ECU controls the following systems and functions: z Printer engine control • paper motion monitoring and control (printing) z Printer laser/scanner • motor z Power system • AC power distribution • DC power distribution • overcurrent/overvoltage protection • high-voltage power distribution ENWW Printer functions 59