Editing Amstrad CPC 464 Maintenance Guide (section)

== Safety Warning ==

The CPC 464 system unit itself is powered from a regulated '''5 V DC, 2 A''' supply on a 2.1 mm centre-positive jack from the matching monitor. The system unit can be opened, cleaned and serviced without high-voltage risk.

The '''CTM-640 / CTM-644 colour monitor''', the '''GT-64 / GT-65 green monitor''' and any third-party CRT contain a '''lethal CRT anode charge''' (10&ndash;25 kV) and mains-side bulk capacitors. Any work that opens the monitor case must follow CRT-safety procedure:

# Power off and unplug the monitor mains lead.
# Wait at least 30 minutes for the CRT and the PSU bulk capacitor to bleed.
# Discharge the CRT anode through a 1 MΩ / 10 W resistor between the chassis ground and the anode cap (slide the resistor under the rubber boot).
# Discharge the PSU bulk capacitor through a 1 kΩ / 5 W resistor before working on the primary side.
# Verify both discharges with a multimeter.

Monitor work is covered in the monitor-specific service manuals; this guide concentrates on the system unit, the keyboard, the cassette mechanism and the routine work that touches both monitor and system unit.