Editing Amstrad CPC 464 Troubleshooting Guide (section)

=== Cassette deck does not load ===

The cassette deck has its own circuit on the cassette sub-PCB (parts 170201&ndash;170212 + 809155&ndash;809175). Test in this order, as per the official "Cassette & Software Analysis" flowchart:

# '''Check connections to tape deck''' &mdash; reseat the sub-PCB ribbon at CP001 on the main PCB.
# '''Clean tape head''' &mdash; IPA on foam swab.
# '''Check head alignment''' &mdash; insert a test tape with constant 6 kHz tone, set volume to max, adjust azimuth screw on the cassette head until pin 7 of IC302 reads 330&ndash;520 mV.
# '''Check the cassette key switches''' &mdash; the play, rewind, fast-forward and pause buttons each operate a leaf switch. Stuck buttons or oxidised leaf-switch contacts will keep the motor from starting.
# '''Check the motor control relay RY301''' &mdash; this relay (part 170123) energises the motor whenever software issues the CASSETTE WRITE or CASSETTE READ commands. A failed relay coil or a failed relay driver transistor will keep the motor permanently off (or, less commonly, permanently on).
# '''Speed''' &mdash; a stretched main belt (part 170204) is the most common end-of-life fault. Symptom: tape loads when the motor is helped by hand, but stops if the motor takes over. Replace the belt.

If the deck is mechanically sound but loading fails with a "Read Error" reported by the firmware:
* Probe the cassette read output at IC302 (LA6324) pin 7 while playing a known-good tape. The signal should be a clean sine-shape at 1 kHz or 2 kHz (software-selectable write speed) at 100&ndash;500 mV peak-to-peak.
* If the signal is correct at IC302 but the firmware still reports "Read Error", suspect Q103 (ZTX312L) which buffers the cassette signal into the 8255 PIO.

The official service note: '''actual physical damage to a software tape will prevent it from loading at all'''. There are no half-working programs on the CPC &mdash; tapes either load completely or do not load. Intermittent loading with retries is a deck mechanical issue, not a tape issue.