7006156

This document is an Engineering Change Order Log (DEC-O-LOG) from Digital Equipment Corporation, dated 1974, detailing modifications for the "Disk Power and Motor Control" system (part number 7006156).

It outlines three specific problems and their respective corrections:

1. Issue 7006156-00001: A chassis track screw was too long, hitting a cable.
   • Correction: The screw size was changed from 3/8 to 5/16 inch, requiring immediate in-plant retrofit.
2. Issue 7006156-00002: Cooling fans were rubbing on their screens.
   • Correction: Washers were added between the fan and screen for spacing, to be applied to production units as soon as possible.
3. Issue 7006156-D0003: Transformer T1 had incorrectly numbered taps, causing the drive motor to overheat and experience speed variations.
   • Correction: The incoming line was relocated to terminal #1 of T1. This required retrofitting all systems before shipment and also retrofitting existing field units at their next preventative maintenance.