LP02

This document is an Engineering Change Order Log from Digital Equipment Corporation for its LP02 Data Products Line Printer, detailing various problems and their corresponding corrections.

The log covers a range of issues from June 1971 to August 1973, including:

1. Critical Hardware Reliability:

   • LP02-A0001 (Jun-71): Addressed a fault where a +22V supply failure could lead to overheating of hammer drivers. The correction involved adding a circuit to sense voltage conditions and clamp leakage current, requiring a 2.0-hour retrofit for all LP02s.
   • LP02-D0007 (Sep-73): Solved a timing problem in the AT-18 module that prevented the printing of the second of two identical, consecutive characters. This required a 1.0-hour board rework and retrofit for affected units.

2. Functional Performance:

   • LP02-00002 (Jun-71): Rectified a design flaw in the Automatic Top of Form function, which only worked correctly for paper with 11-inch folds, causing misalignment with other paper sizes. The solution was to disable this function.

3. Safety and Serviceability:

   • LP02-C0003 (Nov-71): Introduced a mechanism to hold the printer's top glass open for service, improving maintenance access. This was a 0.5-hour retrofit for specific serial numbers.
   • LP02-A0006 (Aug-73): Addressed a personnel hazard where the pick-off bar could act as a cutter. The correction involved adding a protective guard, a 0.5-hour retrofit for listed printers.

4. Product Inclusion and Documentation:

   • LP02-00004 (Apr-72): Mandated the inclusion of a paper receptacle on all LP02 Line Printers, phased in after April 30, 1972.
   • LP02-0004A (May-72): Corrected an error in the "break-in/effectivity" instructions for a previous ECO (LP02-00004).
   • LP02-00005 (Oct-72): Updated the LP02 drawings to include an accessory list.

Most corrections were implemented as immediate retrofits, either universally or for specific serial numbers, with typical installation times ranging from 0.5 to 2.0 hours.