Amstrad CPC 6128 Service Manual
The CPC6128 Micro Computer / CTM644 Colour Monitor / GT65 Green Monitor Service Manual is Amstrad Consumer Electronics plc's own service manual for the CPC 6128 and its two monitors. 31 pages, cover price £8.00. The scan has no text layer, so values must be read from the page images.
Contents
Amstrad's own contents list, with printed page numbers:
- Safety test — 2
- Keyboard exploded view and parts list — 3
- CPC6128 basic hardware analysis — 4
- Function diagrams — 5–6
- Software errors — 7
- Diagnostic flow chart — 8, 9, 10, 11
- Alignment checks — 12, 13, 14, 15
- CPC6128 main PCB — 16, 17, 18
- CPC6128 CPU circuit diagram — 19, 20
- Electrical parts list — 21
- GT65 exploded view and cabinet parts list — 22; GT65 circuit diagram and voltages — 23; GT65 main PCB and alignment instructions — 24; GT65 electrical parts list — 25
- CTM644 cabinet drawing and electrical parts list — 26; CTM644 electrical parts list and alignment instructions — 27; CTM644 electrical parts list and voltages — 28; CTM644 circuit diagram — 29, 30
- Main PCB — 31, 32; interface circuit diagram — 33, 34; disc control circuit diagram — 35, 36; cassette control circuit diagram — 36; mechanism and mechanical replacements — 37
- Technical specification — back page
What it settles
The electrical parts list on page 21 gives value, circuit reference and Amstrad part number for every component on the CPC 6128 main board, with separate lists for the GT65 and CTM644 monitors on pages 25 and 26–28. Those monitor sections also carry voltage charts, which is what makes a monitor fault diagnosable rather than guessable.
From the technical specification on the back page:
- Z80A at 4 MHz; 128K of RAM arranged as two 64K banks (over 41K available in BASIC, 61K TPA under CP/M Plus); 48K of ROM containing BASIC, the operating system and the disc extensions; 6845 CRT controller; AY-3-8912 three-voice sound generator; 8255 parallel I/O.
- 74-key keyboard; three display modes — 4 colours from 27 at 320 × 200, 2 from 27 at 640 × 200, 16 from 27 at 160 × 200.
- The disc drive is a 3-inch system to the Hitachi/Panasonic standard, with the software configured for a 12 ms step rate and 30 ms settling time, and the system is designed to control a maximum of two drives.
- The machine has no internal power supply. The technical specification states the power supply as "Screen System: 240 V AC 50 Hz (keyboard and disc drive power supplied by screen system)", with a 5 mm socket for the 5 V supply, "supplied exclusively from monitor", and a separate 5 mm plug and lead to connect the 12 V (disc) power socket on the monitor. A 6128 will not run without a monitor or an equivalent supply, and it needs both rails — a fault that presents as a dead drive with a working machine is often the 12 V lead.
What this manual does not contain
- No text layer, so nothing can be searched.
- No coverage of the CPC 464, 664, or the Plus range.
- No PSU component data beyond the monitor sections — the supply is inside the monitor, and the monitor parts lists are the relevant ones.
- Later main-board revisions are not covered here; see Amstrad CPC 464 / CPC 6128 / GT65 / CTM644 / MP3 / CT1 Service Manual Amendment.
Download here: Amstrad CPC6128 Service Manual.pdf