Apollo Lunar Module (LM) Guidance and Navigation System Power and Servo Assembly (PSA), measuring 23.25 x 9 x 7 and weighing approximately 28 pounds, featuring an orange acrylic front with 10 output connectors. The back is stamped with part numbers, "SN 49732, Signal Conditioner Assy, LEM-Flight / Qual, Eng Model, S/N 3," and bears an affixed metal NASA plate: "Apollo G & N System, Power & Servo Assembly-LEM, Part No. 6007200, Serial No. ACSK 1, Contr. No. NAS 9-497, Designed by MIT Instrumentation Lab, Mfg by AC Electronics Div. GMC."
The PSA, located just below the display and control panel in the lower equipment bay, served as a central mounting point for most of the G&N electronic units such as power supplies and amplifiers. It also contained the backup electronics used to supply timing pulses to the IMU in case of an AGC timing malfunction. It consisted of 10 removable trays mounted adjacent to each other and connected to a junction box. The PSA trays utilize three wiring harnesses to provide electrical connection: one for module-to-module connection, another for module-to- junction box connection, and a third for module connection to a 38-pin female test plug on the front of the PSA tray.
