PC04

This document is a 1973 Engineering Change Order Log from Digital Equipment Corporation for the PC04 Paper Tape Reader and Punch. It outlines two main sets of modifications:

1. Cost Reduction (March 1973 - PC04-00057): Changes were implemented to reduce manufacturing and assembly costs by replacing expensive aluminum and machined parts (bezel, reader plate, tape path guide) with plastic and die-cast alternatives.
2. Documentation & Reliability Improvements (September 1973 - PC04-D0058):
   • Documentation: Missing engineering drawings for the Power Regulator Board and the Illustrated Parts Breakdown (IPB) were added to the documentation sets to assist Field Service.
   • Reliability: The 4 AMP fast blow fuse (F2) was replaced with a 4 AMP slow blow fuse on the Power Regulator Assembly to prevent it from blowing during PC04 power-on/off cycles. This fuse change was implemented in production and recommended for field retrofits if issues arose.