Amstrad PCW 8512 Maintenance Guide
The Amstrad PCW 8512 shares its monitor unit, power supply, CPU board, printer and keyboard with the Amstrad PCW 8256, so routine care, the supply and monitor alignment, the drive belt and the printer are covered once, in the Amstrad PCW 8256 Maintenance Guide. What the 8512 adds is a second, double-sided drive and a second bank of memory, covered below.[1]
Warning: the drives sit in the monitor unit beside the mains power supply and the CRT. Follow the safety steps in the 8256 maintenance guide and the CRT Discharge Procedure before opening the case.
Drive B
[edit | edit source]Drive B is the lower drive. The cabinet parts list gives it as a Compact Floppy Disc Drive EME-231 (part 171224); the 8256's single drive is an EME-155.[1] Drive A in the 8512 is the same as the 8256's, but drive B is not: it writes double density and reads and writes both sides of the disc without turning it over.[2][3]
Discs
[edit | edit source]- Use double-density CF-2DD discs in drive B, formatted there with DISCKIT from side 2 of the system disc.[3]
- Insert a drive B disc with side 1 nearest the screen, every time.[3]
- A disc formatted in drive B cannot be used in drive A, and drive B must not write to a CF-2 disc made in drive A; it can only read it.[3]
- Users found that ordinary CF2 discs also work in drive B, which helps now that CF2DD discs are hard to find.[2]
Belt and mechanism
[edit | edit source]Amstrad's mechanical replacement page (p. 10) is printed with the flow charts and alignment checks that cover both drives. Its spindle motor procedure removes the drive belt and ends with the index period set to 200 ±2 ms at VR201.[1] Belt replacement, the cleaning of the old rubber off the pulley, and the write-protect pin warning are in the 8256 guide.[2]
Alignment figures for drive B
[edit | edit source]Amstrad prints the drive B (FD2) figures in brackets beside those for drive A. The test disc for drive B is the EME-CF2DD; the test points are the same: TP1 and TP2 for the read signal, TP3 and TP11 for ground, TP5 for the track 00 sensor and TP9 for the index.[1]
| Check | Drive A (FD1) | Drive B (FD2) |
|---|---|---|
| Radial alignment track | 19 | 39 and 119 |
| Index burst and azimuth track | 39 | 79 and 159 |
| Index timing after adjustment | 500 ±100 µs | 500 ±200 µs |
| Index timing at track 00 | 500 ±200 µs | 500 ±300 µs |
| Head output | 140 mV p-p or more | 70 mV p-p or more |
| Positioning, maximum before adjustment | 26 µm | 19 µm |
| Positioning, target after adjustment | below 15 µm | below 5 µm |
| Azimuth bursts shown | −12′, 0′, +12′ | −24′, 0′, +24′ |
| Track 00 compared with | Track 39, within 18 µs | Track 79, within 18 µs |
Amstrad's notes say the second drive "is subject to separate service information" and that no work should be done on its mechanism or board: faulty second drives were exchanged.[1]
Memory
[edit | edit source]The 8512 fills all sixteen DRAM positions, IC104–IC119, with TMM41257P-15 chips, and the memory links are set A off, B on, C off, D on.[1] The upper eight, IC112–IC119, are the parts the 8512 adds.[1] The RAM disc should be 368K; see the Amstrad PCW 8512 Troubleshooting Guide if it is smaller.
Keyboard
[edit | edit source]The 8512 keyboard is marked 512K but is the same as the 8256's, and either can be used.[2] Its care is covered in the 8256 guide.
Related pages
[edit | edit source]- Amstrad PCW 8512 · Amstrad PCW 8512 Troubleshooting Guide · Amstrad PCW 8256 Capacitor Replacement Guide
- Amstrad PCW 8256 Maintenance Guide
- Floppy Drive Repair · CRT Discharge Procedure
References
[edit | edit source]- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 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. Drive flow charts pp. 5–9 and alignment checks pp. 11–14, with the FD2 figures in brackets; mechanical replacements p. 10; cabinet parts list p. 23 (PDF p. 24); PCW8512 parts list p. 34 (PDF p. 35); memory options table (PDF p. 36).
- ↑ 2.0 2.1 2.2 2.3 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. Drive A of the 8512 the same as the 8256's; drive B double-sided, 720K, side 1 to the left; CF2 discs used in place of CF2DD; the drive belt as the most common fault; cleaning old rubber off the pulley.
- ↑ 3.0 3.1 3.2 3.3 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. Part III, Two-Drive Operation, pp. 1–8.