Amstrad PCW 10 Capacitor Replacement Guide
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The Amstrad PCW 10 has its power supply inside the main unit, and that supply also feeds the 9-pin printer through the single printer cable.[1][2][3] No capacitor values have been published for the PCW 10 itself: Amstrad's service manual for it is not available, and the published lists are for the related PCW 9256 and PCW 9512+. Which of those lists can be used depends on the boards fitted to your machine.
Safety
[edit | edit source]Warning: the main unit runs from the mains and contains a CRT. The supply's mains reservoir capacitor and the tube both hold a dangerous charge after the plug is pulled.
- Unplug the machine and the printer before opening the case, and discharge the tube; see CRT Discharge Procedure.
- On the 9256 the mains reservoir is C505, 150 µF 400 V, and on the 9512+ it is C5005, 150 µF 400 V. Find the equivalent part on your board and measure across it before touching anything.[4][5]
- After the work, run Amstrad's safety tests for these machines: a 4 kV flash test and an insulation resistance of at least 4 MΩ between the joined mains live and neutral and all accessible metal on the outside.[4]
Which list applies
[edit | edit source]Read the board numbers on your PCW 10 and compare them with the two manuals. The maintenance guide explains how to reach the boards and what to look for.
| If your board is | It matches | Use |
|---|---|---|
| Monitor board MM0059, CPU board MC0127 | PCW 9256 | Amstrad PCW 9256 Capacitor Replacement Guide: 19 entries covering 30 positions, from the parts list |
| Monitor board MM0041A, main board MC0130A | PCW 9512+ | Amstrad PCW 9512+ Capacitor Replacement Guide: 29 entries covering 52 positions and two tantalums |
| Anything else | Neither | Record your own board as below |
Sources: the 9256 and 9512+ service manuals.[4][5]
Even on a board whose number matches, read each part before ordering. The Joyce Computer Club reports, second-hand, that the PcW10's design was altered slightly because some components were no longer available, and PCW Today later wrote that parts had become scarce and the PcW10 would soon have been too expensive to make.[2][6]
Recording your own board
[edit | edit source]- Photograph both sides of the monitor board and the main board, with the board numbers in shot.
- For each electrolytic, write down the designator, capacitance, voltage, temperature rating, can size and polarity.
- On the 9256 and 9512+, Amstrad numbers the supply parts in a series of their own: the 500 series on the 9256 and the 5000 series on the 9512+.[4][5] Check which pattern your board follows.
- Compare your table with the matching list, if there is one, and note every difference.
Where to start
[edit | edit source]The supply carries the computer, the drive and the printer, so its electrolytics come first. On the 9256 those are the 500-series parts on the monitor board, with C505 as the 400 V reservoir.[4] The Joyce Computer Club's 9256 photographs show the supply board lifted out from under the monitor, with its heat sinks and capacitors.[3] For what failed parts look like, see Capacitor Failure Symptoms.
Procedure
[edit | edit source]- Unplug the mains lead, the printer cable and the keyboard, and remove the back cover.[3]
- Discharge the CRT and the mains reservoir capacitor.
- On the 9256 the supply sits directly below the monitor and lifts out; lift out the supply board to reach its underside, noting how the cables are routed.[3]
- Record every electrolytic as above before removing any of them.
- Replace one part at a time with the same capacitance and the same or a higher voltage rating. Check the polarity marking on the board before soldering each one, and keep the reservoir at 400 V or above.
- Inspect the joints round the switching transformer, the heat-sinked parts and the connectors, and reflow any that are cracked.
- Reassemble, run the safety tests, then check the outputs before refitting the cover.
After the recap
[edit | edit source]If the monitor board is the 9256's, set the outputs at connector A with Amstrad's chart: CP101 disconnected, VR401 at maximum and electronic loads of 1.8 A on 5 V, 1.2 A on 12 V and 1.2 A on 24 V; 12 V is set with VR502 to within 0.01 V, 5 V with VR501 to within 0.05 V, and 24 V is checked to within 1 V.[4] If it is the 9512+'s, follow the chart in the 9512+ guide. Then check that the PCW 10 boots and that the printer feeds and prints.
Related pages
[edit | edit source]- Amstrad PCW 10 · Amstrad PCW 10 Maintenance Guide · Amstrad PCW 10 Troubleshooting Guide
- Amstrad PCW 9256 Capacitor Replacement Guide · Amstrad PCW 9512+ Capacitor Replacement Guide
- Capacitor Failure Symptoms · CRT Discharge Procedure · Recommended Tools
References
[edit | edit source]- ↑ Wikipedia, "Amstrad PCW". Retrieved 2026-10-19. "In all models, the monitor's casing contains the CPU, RAM, floppy disk drives, and power supply for all of the systems' components."
- ↑ 2.0 2.1 Joyce Computer Club (Amsterdam), "PcW 10 Gallery", fvempel.nl, last updated 29 July 2007. Retrieved 2026-10-19. A look-alike of the PcW 9256, on the market in August 1993; the single printer cable carrying the printer's power; the report that the design was altered slightly because components were unavailable, from an owner who had not yet opened his machine.
- ↑ 3.0 3.1 3.2 3.3 Joyce Computer Club (Amsterdam), "Upgrading memory of a PcW 9256", fvempel.nl, last updated 29 July 2007. Retrieved 2026-10-19. The 9256 and PcW10 share the later case design; on the 9256 the back cover is held by four screws, the power supply sits directly below the monitor and the main board below the supply, under a foil and a metal shield; photographs of the supply board removed.
- ↑ 4.0 4.1 4.2 4.3 4.4 4.5 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. Safety tests p. 2; alignment chart p. 3; monitor/CRT board layout p. 4; electrical parts list pp. 16–17 (board assemblies MM0059 and MC0127; mains fuse F501 3.15 A time-lag; electrolytic capacitors, including C505 150 µF 400 V).
- ↑ 5.0 5.1 5.2 Amstrad plc, PCW9512+ Personal Computer Word Processor Service Manual. Hosted as File:Amstrad PCW 9512 Plus Service Manual.pdf, described at Amstrad PCW 9512+ Service Manual. Safety tests p. 2; alignment chart p. 3; main board MC0130A p. 16 (PDF p. 15); monitor/CRT board MM0041A p. 18 (PDF p. 17); electrical parts list, capacitors (PDF p. 30), including C5005 150 µF 400 V.
- ↑ PCW Today issue 9, cover feature "The Verdict!" on the PcW16: the PcW10 on sale with demand for it, but parts scarce and the machine soon to become too expensive to mass-produce. Scan at archive.org/details/PcwToday9. Retrieved 2026-10-19.