Editing Amstrad CPC 664 Troubleshooting Guide (section)

== Floppy Drive Symptom Catalogue ==

The Hitachi 3-inch drive in the CPC 664 has well-known wear failures. The community-documented symptoms are:

=== Drive motor does not run ===

* Verify +12 V at the drive motor power pin with a multimeter.
* If +12 V is present but motor does not run: motor brushes worn (rare on Hitachi 3-inch), or motor relay (where used) failed.
* If +12 V is absent: drive power lead detached from the system unit's PSU input.

=== Drive motor runs but disc does not spin ===

'''Most common 664 fault.''' The rubber drive belt (54 &times; 1 mm flat) connecting the motor to the spindle has perished, liquefied or stretched.

Symptom: system reports "Disc missing" or "Read fail a" even with a known-good disc inserted, because the spindle is not spinning so no tracks can be read.

Fix: Replace the drive belt. Procedure is in [[Amstrad CPC 664 Maintenance Guide]].

=== Disc spins but reads fail with "Disc error" ===

* '''Head dirty''': clean with IPA on a foam swab.
* '''Disc itself faulty''': try a known-good disc. 3-inch discs from the 1980s sometimes develop binder failures and shed oxide.
* '''Head alignment off''': rare; the drive needs alignment-disc service.
* '''AMSDOS ROM''': reseat or replace.

=== "Track 0" error or stepper stuck ===

The stepper motor cannot find track 0. Causes:
* Dried lubrication on the worm-drive lead screw &mdash; apply a single drop of clock oil to the lead screw (per [[Amstrad CPC 664 Maintenance Guide]]).
* Track 0 sensor (optical interrupter at the inner end of the head travel) blocked by dust.
* Stepper motor coil failed (rare).

=== Disc reads but writes fail ===

* Disc write-protect tab in the protected position.
* Drive head failing on the write side (rare, usually paired with read failures eventually).
* AMSDOS reports "Disc is read only" &mdash; verify the disc and not the drive.

=== Disc detected but CAT shows random / corrupt directory ===

* Disc not formatted with AMSDOS / CP/M file system &mdash; try formatting first.
* Drive belt is intermittently slipping &mdash; the disc spins at the wrong speed and the FDC decodes wrong bytes. Replace the belt.