RK05 FCO field change order

This document is Field Change Order (FCO) RK05-00064, issued by Digital Equipment Corporation (DEC) on August 6, 1976, for the RK05 Disc Drive. It is a mandatory retrofit designed to significantly improve the reliability of all RK05 drives, superseding previous FCO versions.

The FCO bundles five Engineering Change Orders (ECOs), each addressing specific reliability areas:

1. Air Handling (ECO RK05-00061): Replaces the old air filter system with a new, high-efficiency filter to improve air quality, ease of maintenance, and prevent future head adjustments, thereby reducing downtime.
2. Capacitor Bracket (ECO RK05-00055): Improves the grounding path for the blower run capacitor, which previously caused random read/write errors.
3. Head Select (ECO G180-00008) & Data Reliability (ECO G180-00009): These two ECOs for the G180 Read/Write Module resolve issues such as hard checksum errors, data writing in wrong sectors, data clipping, undesirable phase shifting, and signal imbalances, all aimed at improving data integrity. Procedures involve etch cutting, wire additions, and component replacements.
4. Overvoltage (ECO 5409484-00005): For the 8-20V Regulator Assembly, this ECO prevents regulator overvoltage at high line voltage and light load conditions, which could lead to voltage breakdown of the 723 chip. The rework includes component replacement, drilling, and precise voltage adjustments.

Installation is estimated to take approximately 3 hours on-site and must be performed by technically qualified personnel. The document strongly advises thoroughly reading all instructions, verifying the completeness of the parts kit, and exercising extreme caution during rework (e.g., unplugging head wires before G180 removal, careful soldering, rechecking connections) to prevent damage. The FCO also references a general "Module Rework/Retrofit and Repair Specification" for detailed workmanship standards.