PDP-8 Family Dectape Field Service Tech Manual

This document provides technical instructions for performing skew adjustments on DECtape systems used with the PDP-8 family. It details the procedure for using a skew tester, including how to calibrate the equipment, perform a skew test, and deskew the tape head if necessary.

Key sections of the document include:

• Skew Testing: Procedures are outlined for testing skew with both certified "zero skew" tapes and standard tapes, including specific cleaning and formatting instructions.
• Deskewing: Steps for cleaning the head, removing obstructions, and using reflective markers (DEC #29-15191) to shim the head for proper alignment.
• Calibration: Instructions for using the G500 Skew Tester, including switch settings (S1, S2, S3) to calibrate signals, select split windings for different head manufacturers, and ensure voltage compatibility with R or M series transports.
• Reference Materials: The manual includes diagrams illustrating skew measurement on an oscilloscope (Figures 1 and 1A), a "link tape" procedure for reversing tape direction, a connector pinout, and a full electronic schematic for the G500 Skew Tester along with a corresponding parts list.