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Amstrad PC5286 Maintenance Guide

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Amstrad PC5286 SIMM sockets (user manual p. 8-12)
The four SIMM sockets on the PC5286 motherboard (user manual p. 8-12)

The Amstrad PC5286 shares its case, keyboard, floppy drive type and user manual with the Amstrad PC5086. Safety, opening the case, the floppy drive, the slot power budget and the keyboard switch are covered in the Amstrad PC5086 Maintenance Guide. The points below are particular to the PC5286's motherboard: memory, the Ni-Cad clock battery, the two option links, the co-processor and the hard disk, with owners' reports on the power supply and capacitors. Faults are in the Amstrad PC5286 Troubleshooting Guide.[1][2] Amstrad's service manual (reference 272826) has not been published online.[3]

Memory

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The PC5286 comes with 1 MB and takes up to 4 MB in four SIMM sockets, IC52 to IC55.[4]

  1. Fit two or four modules of the same type, either 256 KB × 8 or 1 MB × 8, rated at 80 ns.
  2. With two modules, use IC52 and IC53, the two sockets nearest the front of the machine.
  3. Insert each module at about 45° and turn it upright, as Amstrad's drawing shows.
  4. Close the case, switch on and run SETUP to record the new memory.[4]

Amstrad's manual specifies ×8 modules, although the leaflet's table describes the memory as parity checked.[4][5]

Memory split recommended by Amstrad for MS-DOS (user manual pp. 1-5 to 1-6)
Memory fitted Base Extended (no LIM software) Expanded available
1 MB 640 KB 384 KB 0–384 KB
2 MB 640 KB 1,024 KB 0–1,024 KB
4 MB 640 KB 3,072 KB 0–3,072 KB

Memory not set as extended in SETUP is available as expanded memory through SCATEMM.SYS. With more than 1 MB, or with 1 MB and the 384 KB relocation turned off, the BIOS copies the system and VGA BIOS into shadow RAM.[1][6]

Clock battery

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Amstrad lists the PC5286's Ni-Cad clock battery as replaceable by a dealer; the CMOS RAM chip itself is not replaceable. The battery charges while the PC is on: after a few months switched off, leave the machine running for about 16 hours to recharge it fully. A flat battery gives "System battery has discharged - Run SETUP".[7][8][9]

Amstrad's leaflet describes the clock as "10 Year Battery-Backed NVR".[5] If the board around the battery shows corrosion, see Battery Explosion, Capacitor or Corrosion Damage; for a replacement pack see Battery Refurbishment.

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Amstrad PC5286 option links (user manual p. 11-9)
LK1 and LK7 on the PC5286 motherboard (user manual p. 11-9)
  • LK1, jumper fitted: built-in VGA enabled (default). Remove it to use a video card in a slot.[2]
  • LK7 powers the CMOS RAM: pins 1 and 2 in normal use, pins 2 and 3 discharged.[2]

To clear a corrupted CMOS RAM that stops SETUP from running:[2][8]

  1. Switch off and remove the cover (screws in the bottom panel, cover forwards).
  2. Move the LK7 jumper from pins 1 and 2 to pins 2 and 3.
  3. Put it back on pins 1 and 2.
  4. Refit the cover, switch on and run SETUP to enter the configuration again, including the hard disk type from the label on the back panel.[10]

The French edition of the manual names LK16 in its troubleshooting chapter for this procedure, but its own board drawing and the English edition give LK7.[11][2]

Co-processor

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A 10 MHz 80287 (80287-10) fits the empty socket on the motherboard. No SETUP change or link is needed.[12]

Hard disk

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  • The 40 MB drive is AT-type IDE. Its type number is on a label on the back panel and must be set in SETUP; types 48 and 49 take user-defined parameters.[10][13]
  • Amstrad expected larger drives to be fitted with an interface card.[13]
  • The heads park automatically at power-off.[7]

Power supply

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No circuit or output specification for the supply has been published. One PC5286 owner, quoting other forum posts, gave the large connector as +5 V on the pink wires, ground on black and +12 V on yellow, with the small connector carrying the negative rails; the PC4386SX supply, whose connectors were photographed and labelled by another owner, uses the same colours (see the Amstrad PC4386SX Maintenance Guide). Measure the outputs of any supply before relying on this.[14]

The expansion slots are specified at +5 V ±5% and +12 V ±5%, which gives a pass range of 4.75 to 5.25 V and 11.4 to 12.6 V at a slot.[2]

Capacitors

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No capacitor values have been published for the PC5286's motherboard or power supply.[3][15] Owners report:[14]

  • capacitor problems in the power supply and on the motherboard of one PC5286, which the owner reported as solved before he turned to the floppy drive;
  • a PC5286 that died when switched on after long storage, which its owner attributed to a capacitor exploding in the power supply.

Before powering a machine that has been stored for years, inspect the supply and board for bulging or leaking capacitors; see Capacitor Failure Symptoms.

The AdLib-compatible sound card bundled with the PC5286 (board 3100-015P-4) has its own electrolytics; one restorer replaced all of them after finding corrosion on a card that had been stored damp.[16]

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References

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  1. ↑ 1.0 1.1 Amstrad plc, PC5086 and PC5286 User Manual and Guide to MS-DOS (1991), pp. 1-3 to 1-4. Specifications of the PC5086 and PC5286.
  2. ↑ 3.0 3.1 Centre for Computing History, "Amstrad PC5086 / PC5286 Service Manual" (CH27479): service manual for the PC5086, PC5286 and the PC14CDR, PC14HRCDR and PC14FMD monitors, reference 272826, 78 pages. Retrieved 2026-10-02.
  3. ↑ 4.0 4.1 4.2 Amstrad plc, PC5086 and PC5286 User Manual and Guide to MS-DOS (1991), pp. 8-10 to 8-12. PC5286 SIMM upgrades.
  4. ↑ 5.0 5.1 Amstrad plc, PC5286 leaflet (1991), p. 2 (specification). Hosted as File:Amstrad PC5286 leaflet (1991).pdf.
  5. ↑ Amstrad plc, PC5086 and PC5286 User Manual and Guide to MS-DOS (1991), p. 8-3. The PC5286 shadow RAM facility.
  6. ↑ 7.0 7.1 Amstrad plc, PC5086 and PC5286 User Manual and Guide to MS-DOS (1991), pp. 13-2 to 13-3. Automatic head parking, the PC5086 CMOS RAM and the PC5286 Ni-Cad battery.
  7. ↑ 8.0 8.1 Amstrad plc, PC5086 and PC5286 User Manual and Guide to MS-DOS (1991), pp. 14-1 to 14-12. Troubleshooting and system messages.
  8. ↑ Amstrad plc, PC5086 and PC5286 User Manual and Guide to MS-DOS (1991), pp. 4-2 to 4-25. SPEED, DISPLAY and MOUSE, SETUP (Ctrl-Alt-S or DOSETUP) and auto-configuration on both models.
  9. ↑ 10.0 10.1 Amstrad plc, PC5086 and PC5286 User Manual and Guide to MS-DOS (1991), pp. 3-2 to 3-11. Ventilation, the XT/AT keyboard switch, monitor power socket, and start-up messages.
  10. ↑ Amstrad, PC5086 et PC5286 Manuel de l'utilisateur et guide MS-DOS (1991), Internet Archive, 558 pages. Retrieved 2026-10-02.
  11. ↑ Amstrad plc, PC5086 and PC5286 User Manual and Guide to MS-DOS (1991), pp. 7-2 to 7-5. Fitting an 8087-2 or 80287-10 co-processor, opening the system unit, and expansion bus speeds.
  12. ↑ 13.0 13.1 Amstrad plc, PC5086 and PC5286 User Manual and Guide to MS-DOS (1991), pp. 9-1 to 9-3. Hard disk compatibility and the PC5286 type table.
  13. ↑ 14.0 14.1 Vogons forum, "AMSTRAD PC 5086 - Floppy Drive Problems", Perro, tecnico, Jason_rg, flufetor, aotta69 and gca, May 2020 to August 2021. Retrieved 2026-10-02. Belt replacement on the original drives, a 26-pin to 34-pin adapter, capacitor failures in PC5286 power supplies and boards, and the PC4386SX power connector pinout.
  14. ↑ acpc.me (ACME) archive, Amstrad PC section, directory DOCUMENTS_TECHNIQUES/SERVICE_MANUALS. Retrieved 2026-10-02. The PC3086/PC3286/PC3386SX, PC4386SX and PC5086/PC5286 service manuals are listed with placeholder images only, marked missing.
  15. ↑ Vogons forum, "Amstrad Adlib Clone: Restoration and Testing", brassicGamer and others, April 2016 to May 2017. Retrieved 2026-10-02. The Amstrad OPL2 sound card 3100-015P-4 bundled with the PC5286; gca reports the same card in his PC4386SX.


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