Editing Amstrad DDI-1 / FD-1 Service Manual

The '''DDI1 / FD1 Service Manual''' is Amstrad Consumer Electronics plc's own service manual for the external 3-inch disc system sold for the [[Amstrad CPC 464]] — the '''DDI-1''' (drive plus plug-on interface) and the '''FD-1''' (second drive). 18 pages. '''No text layer''', so values must be read from the page images.

== Contents ==

Amstrad's own contents list:

* Technical specification; safety test
* '''Cabinet drawing''' and '''cabinet parts list'''
* '''Software errors'''
* '''Diagnostic flow chart'''
* '''Power board PCB'''
* Interface circuit diagram — 10, 11
* Circuit diagram — 12, 13
* Relay PCB — 14
* Interface PCB — 15
* '''Alignment checks''' — 16
* Mechanism — 20

== What it settles ==

'''Each drive has its own integral mains power supply.''' Amstrad's specification states it plainly, and adds that the first drive (the DDI-1) '''also supplies power to the disc expansion interface through the interconnecting cable'''. This is the opposite of the computer itself, which takes all its power from the monitor: the DDI-1 and FD-1 are mains-powered devices with a transformer inside, and should be treated as such.

'''The drive mechanism is belt-driven, and Amstrad sells the belt.''' The cabinet parts list names the mechanism as a '''Compact FDD EME-150A''' (Amstrad part 190005) and lists, individually, the '''stepper motor''', the '''head assembly''', the '''capstan motor''' and a '''drive belt''' (part 190015) — along with the mains transformer 0675001E (190003), the interface connector PCB assembly (190004), the slide switch and the edge connector. A perished belt is a documented, replaceable fault on these drives.

'''Amstrad's own drive specification''': a 3-inch system conforming to the '''Hitachi/Panasonic standard''', with the software configured for a '''12&nbsp;ms step rate''' and '''30&nbsp;ms settling time'''; the system is designed to control '''a maximum of two drives'''; and the interface houses an expansion ROM containing AMSDOS and the machine-dependent parts of CP/M and LOGO.

'''The "software errors" section is a diagnostic procedure in itself.''' Before blaming the drive, Amstrad sets out how to distinguish a soft error from a hardware fault: re-read the track ten times or more; if that fails, step the head to the adjacent track in the same direction as it last moved and return it, then re-read; if the data still does not come back, the error is not recoverable. For write errors, repeat the write and write-check up to ten times, then test another track, then another disk — and only if the error follows the drive is the drive at fault. For seek errors the suspects are the step motor, its drive circuit, and carriage torque; recovery is a re-calibration to track 00 followed by a re-seek.

Amstrad also notes that '''the drive is not ready until two revolutions after the disc is inserted''', which is normal behaviour and not a fault.

== What this manual does not contain ==

* '''No mechanism-level repair.''' Amstrad states that faulty drive mechanisms are to be returned for replacement and that service agents should not attempt repairs to the mechanism or to its PCB.
* '''No electrical parts list with component values''' for the interface or power board — the parts list is the cabinet/assembly list. Values must be read from the circuit diagrams on pages 10&ndash;13.
* '''No text layer''', so nothing can be searched.
* Nothing on the built-in drives of the CPC 664, CPC 6128 or the 6128 Plus.

<pdf> File:Amstrad DDI-1 FD-1 Service Manual.pdf </pdf>

Download here: [[:File:Amstrad DDI-1 FD-1 Service Manual.pdf|Amstrad DDI-1 FD-1 Service Manual.pdf]]

== Related pages ==

* [[Amstrad CPC 464]] · [[Amstrad CPC 464 Maintenance Guide]] · [[Amstrad CPC 464 Troubleshooting Guide]]
* [[Floppy Drive Repair]]

[[Category:Amstrad Service Manuals]]
[[Category:Service Manuals]]