R405

This document is a proprietary schematic for the Digital Equipment Corporation (DEC) CRYSTAL CLOCK R405, copyrighted in 1964.

Key information includes:

• Purpose: Intended exclusively for test and maintenance, with the circuits being proprietary.
• Circuit Details: Features a complex arrangement of resistors (mostly 1/4W, 5%), capacitors, transistors (Q1-Q7, specified as DEC 3639-0 or 2N3009), diodes (D1-D17, including Zener diodes IN748), an inductor (L1), and a crystal (CRI).
• Power Rails: Operates with +10V (OA), -15V (OB), and Ground (OC GND), along with a -3V "STRATE" point.

• Component Specifications:

  • Resistors are generally 1/4W, 5% tolerance unless otherwise indicated.
  • Transistors are typically DEC 3639-0.
  • Values for the inductor (L1), capacitor (C1), and crystal (CRI) are referenced in a separate document (DWG CHART A-00517-2).

• Conversion Chart: A "Transistor & Diode Conversion Chart" provides equivalent EIA part numbers for DEC components (e.g., DEC3639 to 2N3639, D662 to IN645, D664 to IN3606).

• Document Control: The drawing is identified as revision "J," with drawing number R405-0-1-, and was drawn by H. Porter and checked by N. Perryman in late 1964.