Amstrad PCW 16 Capacitor Replacement Guide
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The Amstrad PCW 16, shown on its own screen as "PcW16", keeps its monitor, mains power supply, main board and floppy drive in the display unit.[1][2] Amstrad's service documentation for the PcW16 has not been published, and no capacitor values for any of its boards are available.
Safety
[edit | edit source]Warning: the display 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.
- The PcW16 does not switch fully off from its own controls. It goes into standby, with the front LED red, and can wake itself to sound a diary alarm.[3][2] Pull the mains plug before opening it.
- Discharge the tube before working near it; see CRT Discharge Procedure.
- Find the supply's mains reservoir capacitor, the largest high-voltage electrolytic near the mains input, and measure across it before touching the board.
- After the work, check for insulation breakdown between the joined mains live and neutral and the metalwork that can be touched from outside. Amstrad's tests for the earlier PCWs are a 4 kV flash test and at least 4 MΩ insulation resistance.[4]
What is known about the boards
[edit | edit source]| Part | Detail |
|---|---|
| Display unit | Monitor, mains supply, processor board and floppy drive in one case[1][2] |
| Case | The back casing is of similar design to the PcW9256 and PcW10; only the front is new[2] |
| Main board | Unfitted space for a further 1 MB of RAM, 1 MB of flash, a hard drive interface and a colour VGA interface[5] |
| Flash site | A bare position for an Intel 28F008 or similar flash chip; Amstrad's Cliff Lawson said fitting one meant dismantling the machine and soldering the chip[6] |
| Reprogramming socket | On the underside, for the cartridge that rewrites the BIOS area of the flash[5] |
| Floppy drive | A standard 1.44 MB PC drive with a standard connection[2] |
The PcW16 keeps its operating system, applications and documents in flash memory, which holds its contents without power.[5] Copy the flash cabinet to floppy discs before any repair; see the Amstrad PCW 16 Maintenance Guide.
Comparing with the PcW9256
[edit | edit source]Because the PcW16 shares the back of the PcW9256 and PcW10's case, check whether its monitor board is also a 9256 part. Amstrad's 9256 manual lists that machine's boards as MM0059 (monitor, with the supply), MS0227 (CRT), MS0233 (AC input) and MC0127 (CPU), and gives a full electrolytic list for them.[4][2] If the numbers on your PcW16's monitor and CRT boards match, the Amstrad PCW 9256 Capacitor Replacement Guide can be checked against them position by position. The PcW16's computer is unrelated to the earlier PCWs, and no published list covers its main board.[7] If the numbers differ, treat the 9256 list as having no bearing on your machine.
Recording your own boards
[edit | edit source]- Photograph both sides of every board before removing anything, with the board numbers in shot.
- For each electrolytic, write down the designator, capacitance, voltage, temperature rating, can size and polarity.
- Note which parts sit in the mains area and which round the switching transformer, and which feed the CRT's deflection circuit.
- Read every value from the part itself.
- Keep the table with the machine.
Where to start
[edit | edit source]Start with the supply: the mains reservoir, the capacitors round the switching transformer and the output smoothing capacitors. Then the monitor's deflection circuit, if the picture is unstable or shrinks. Capacitor Failure Symptoms shows what failed parts look like.
Procedure
[edit | edit source]- Pull the mains plug, disconnect the keyboard, mouse and any printer, and copy the cabinet to floppy disc.
- Open the display unit and discharge the CRT and the mains reservoir capacitor.
- Record every electrolytic as above.
- Replace one part at a time with the same capacitance and the same or a higher voltage rating, fitted the same way round as the old one.
- Inspect the joints round the switching transformer, the heat-sinked parts and the connectors, and reflow any that are cracked.
- Reassemble and check insulation before refitting the case.
After the recap
[edit | edit source]No supply voltages or alignment figures for the PcW16 have been published. Check that the machine starts into Rosanne from flash and that the picture is stable and correctly sized. A start from cold runs a memory check that a start from standby skips, so a cold start is the better test.[2] Then format and read back a floppy disc.
Related pages
[edit | edit source]- Amstrad PCW 16 · Amstrad PCW 16 Maintenance Guide · Amstrad PCW 16 Troubleshooting Guide
- Amstrad PCW 9256 Capacitor Replacement Guide
- Capacitor Failure Symptoms · CRT Discharge Procedure · Recommended Tools
References
[edit | edit source]- ↑ 1.0 1.1 Wikipedia, "Amstrad PCW", section "PcW16". Retrieved 2026-10-19. "In all models, the monitor's casing contains the CPU, RAM, floppy disk drives, and power supply"; the PcW16's display unit containing the processor, motherboard and RAM.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 Joyce Computer Club (Amsterdam), "PcW16 Rosanne", fvempel.nl, last updated 29 July 2007. Retrieved 2026-10-19. Owner's first impressions with photographs: the back casing of similar design to the PcW 9256 and PcW 10, only the front case new; a standard 1.44 MB PC drive with a standard connection; the red front LED while the machine is still powered; a cold start checks the memory, a warm start does not.
- ↑ Nathan Lineback, "Amstrad PcW16", Toasty Tech GUI Gallery. Retrieved 2026-10-19. Standby mode and wake-up for diary alarms; 1 MB flash and 1 MB RAM; monochrome 640 × 480 display; 1.4 MB floppy drive.
- ↑ 4.0 4.1 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; monitor/CRT board layout p. 4; electrical parts list pp. 16–17 (board assemblies MM0059 monitor, MS0227 CRT, MS0233 AC input, MC0127 CPU; C505 150 µF 400 V).
- ↑ 5.0 5.1 5.2 John Elliott, "The PCW16", seasip.info, written 1995, updated 30 April 1999. Retrieved 2026-10-19. 1 MB RAM and 1 MB flash; the first 64K of the flash rewritable only through a reprogramming cartridge plugged into the underside; spare board space for more RAM and flash, a hard drive interface and a colour VGA interface, "probably" needing professional fitting; no expansion port.
- ↑ Brian Watson (ed.), "The PcW16 pages", 8BIT issue 19, May 1998, pp. 23–27, reprinting comp.sys.amstrad.8bit postings by Cliff Lawson (Amstrad) and Howard Fisher (LocoScript Software), April 1998. Scan at archive.org/details/8Bit-fanzine-19. Retrieved 2026-10-19.
- ↑ Richard Lloyd, PCW article, Amstrad CPC User Club Magazine (ACUC) issue 1, June 2022. Scan at archive.org. Retrieved 2026-10-19. "PCW16 was a unique computer/software package that was not related to previous models."