Comparator W520

This document is a technical schematic for the Digital Equipment Corporation (DEC) "Comparator W520" circuit board. It illustrates the electronic circuitry, including the arrangement of transistors (DEC 3639B and DEC 3009B), diodes (D-662 and D-664), and various resistors required for operation. The schematic notes that it is intended for test and maintenance purposes and includes a parts list reference (A-PL-W520-0-0) and a transistor/diode conversion chart.