Amstrad PCW 9256 Maintenance Guide
The Amstrad PCW 9256 keeps its power supply, monitor, computer board and 3.5-inch drive in one unit and drives a separate 9-pin dot matrix printer. Amstrad's service manual for it gives the safety tests, a full alignment chart for the supply, monitor and printer, the board layouts and a parts list, but no drive service section.[1] The printer is the same mechanism as on the Amstrad PCW 8256, whose maintenance guide covers its ribbon and head lever in full.
Safety
[edit | edit source]Warning: the main unit contains the mains power supply and a CRT. Both can hold a dangerous charge after the plug is pulled.
The monitor board drawing outlines the area at mains potential and marks it "danger mains voltage". The mains fuse F501 (3.15 A time-lag, 250 V, part 171531) sits inside that area in holders FH501 and FH502, beside the brown and blue mains leads at connector CP502. The supply's reservoir capacitor is C505, 150 µF 400 V.[1]
- Unplug the machine and discharge the tube before working near it; see CRT Discharge Procedure.
- Measure across C505 and discharge it before touching the supply.
- After any repair, run Amstrad's safety tests: a 4 kV flash test, and an insulation resistance of at least 4 MΩ, both between the joined mains live and neutral and all accessible metal on the outside of the case.[1]
Cleaning
[edit | edit source]Amstrad's PCW user guides ask for an aerosol anti-static foam cleaner on the screen and case and rule out spirit-based cleaners.[2][3] Clear paper dust from the printer with a blower or a vacuum cleaner nozzle.[2]
Power supply and monitor alignment
[edit | edit source]Amstrad's chart uses a digital voltmeter, an oscilloscope, a frequency counter, a test pattern generator, and the RP3 or a pattern disc. The supply is measured at connector A with CP101 disconnected and an electronic load on each output, as in Fig. 2-1: 1.8 A on 5 V, 1.2 A on 12 V and 1.2 A on 24 V. Reconnect CP101 after the tests.[1]
| Step | Adjustment | Signal in / measure at | Method |
|---|---|---|---|
| 1 | 24 V | Connector A, digital voltmeter | Check 24 V ±1 V (no adjuster) |
| 2 | 12 V | Connector A | Set VR502 for 12 V ±0.01 V, with VR401 at maximum |
| 3 | 5 V | Connector A | Set VR501 for 5 V ±0.05 V, with VR401 at maximum |
| 4 | Vertical size | RP3 or pattern disc; screen | VR405 for full size, I = K = 10 ±2 mm (Fig. 2-2) |
| 5 | Linearity | RP3 or pattern disc; screen | Adjust the deflection yoke for even spacing from the centre: A−B, J−K and L−J each 3 mm or less |
| 6 | Horizontal hold | Free running, no input; pin 5 of CP401 | VR404 for 15.625 kHz |
| 7 | Sub-brightness | RP3 or pattern disc; screen | Brightness and contrast to minimum; VR402 for a dim pattern |
| 8 | Printer strobe timing | RP3 printer test; screen | Turn VR701 either way until the RP3 reports the strobe timing "OK"; it must be neither too long nor too short |
VR701 is on the printer board, next to IC702.[1] For the supply's electrolytics see the Amstrad PCW 9256 Capacitor Replacement Guide.
Disc drive
[edit | edit source]The drive is a UODC-45A (part 272508), 3.5-inch, 720K.[1] The service manual has no drive section and gives no drive adjustments; the 3-inch drive procedures in the 8256/8512 manual are for a different mechanism. Clean the heads and check the drive as for any 3.5-inch drive; see Floppy Drive Repair.
Community advice for fitting a Gotek floppy emulator to a PCW is to check the drive power cable first: Amstrad's drive power wiring is not the PC standard, and a Gotek connected without modification is destroyed.[4] Let a machine that has been stored in a loft or garage stand in a warm room for a couple of days before switching it on.[4]
Printer
[edit | edit source]The 9256's printer mechanism is Amstrad part 171127, the same assembly as on the PCW 8256 and 8512, and the 8256/8512 service manual has its full mechanical parts list.[1][5] The ribbon cassette and print head lever are handled as in the 8256 guide. 1990s dealers sold one ribbon for the PCW 8256, 8512, 9256 and PCW 10.[6] The tractor unit is part 171211.[1] No other printer can be used on the 9256's printer socket.[1]
After work on the printer board or its cable, check the strobe timing with the RP3 printer test (step 8 above).[1]
Keyboard
[edit | edit source]The 82-key keyboard has its own board (MK0011) carrying the Amstrad 40027 controller (IC301) and a 5 MHz ceramic resonator (X301), and a DIN cord (CD303, part 272802). The parts list gives the complete keyboard as part 272633.[1]
Related pages
[edit | edit source]- Amstrad PCW 9256 · Amstrad PCW 9256 Troubleshooting Guide · Amstrad PCW 9256 Capacitor Replacement Guide
- Amstrad PCW 8256 Maintenance Guide · Amstrad PCW 9512+ Maintenance Guide
- Floppy Drive Repair · CRT Discharge Procedure · Recommended Tools
References
[edit | edit source]- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 Amstrad plc, PCW9256 Personal Computer Word Processor Service Manual. Hosted as File:Amstrad PCW 9256 Service Manual.pdf, described at Amstrad PCW 9256 Service Manual. Technical specification and safety tests p. 2; alignment instructions with Fig. 2-1 (supply loads) and Fig. 2-2 (test pattern) p. 3; monitor/CRT board layout p. 4; printer board p. 5; electrical parts list pp. 16–17.
- ↑ 2.0 2.1 Amstrad, The PCW8256 and PCW8512 User Guide and Guide to Locomotive Software's LocoScript (AMSOFT, 1985). Hosted as File:Amstrad PCW8256 PCW8512 User Guide (1985).pdf, described at Amstrad PCW 8256 / PCW 8512 User Guide. Chapter 1, p. 8 (cleaning); Appendix II, pp. 145–148 (printer: ribbon, head lever, dust).
- ↑ Amstrad, PCW9512 Ordinateur Personnel Traitement de Texte – Manuel de l'utilisateur (1987, French). Hosted as File:Amstrad PCW9512 User Manual (1987, French).pdf, described at Amstrad PCW 9512 User Manual (French). Part 1, chapter 2, p. 16 ("Nettoyage de votre PCW"): anti-static foam aerosol, no alcohol-based cleaners.
- ↑ 4.0 4.1 Richard Lloyd, PCW article ("Fifty two years and counting"), Amstrad CPC User Club Magazine (ACUC) issue 1, June 2022. Scan at archive.org. Retrieved 2026-10-02. Gotek drive emulators and the non-standard Amstrad drive power cable; letting a stored machine acclimatise before switching on.
- ↑ Amstrad, PCW 8256/8512 Personal Computer Word Processor Service Manual. Hosted as File:Amstrad PCW 8000 Series Service Manual.pdf, described at Amstrad PCW 8256 / PCW 8512 Service Manual. Printer mechanical parts list, printer mechanical assembly 171127, p. 30 (PDF p. 31).
- ↑ PCW Today issue 7 (autumn 1997), dealer advertisement: "Ribbon for PCW 8256/8512, 9256, PCW10" and "Ribbon for PCW 9512, 9512+". Scan at archive.org/details/pcw-today-07. Retrieved 2026-10-02.