TU78 Subsystem Pocket Service Guide

This Technical Change Notice (EK-0TU78-PS-CN1) for the TU78 Subsystem Pocket Service Guide (EK-0TU78-PS-002) details two major updates to the TU78 power supply:

1. New Power Transformer Voltage Tap Configuration: Drives shipped from the vendor with serial numbers around 12500 and higher feature a new configuration for the power transformer voltage taps. Users should compare their unit's transformer terminal strip (Figure C-1) to Table C-1 (early models) and Table C-2 (later models) to determine its specific configuration.

2. Additional Fuse Panel and Fuses: To prevent component failures, additional fuses have been added to the power supply. The document illustrates the early type of fuse panel (Figure C-2) and the newer fuse panels (Figure C-3), providing associated voltage ranges for each in Table C-3 and Table C-4, respectively.

Important Note: The presence of the new fuse panel does not necessarily mean the new power transformer voltage tap configuration is also present. Users must visually compare their specific tape drive to the provided figures and tables to identify the modifications.