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Amstrad ALT-286 Maintenance Guide

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Amstrad ALT286 main PCB layout
ALT286 main PCB, top view (Amstrad service manual p. 14)

The Amstrad ALT-286 shares its power supply, battery pack, display, VGA board, keyboard and case with the Amstrad ALT-386SX. The safety notes, battery pack, backup battery, display, drive and fan procedures are written once, in the Amstrad ALT-386SX Maintenance Guide, and apply to the ALT-286 unchanged. The sections below cover what is specific to the ALT-286.[1]

Power and battery

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Amstrad ALT-286 rating label
The ALT-286 rating label

The rating label gives the mains supply as 120–240 V, 50/60 Hz, 60 W, rated current 730–440 mA, and the battery as 12 V DC.[2] The power supply unit (UN-1, part 270492) and the BAT-1 battery pack (12 V 2400 mAh NiCd, part 270450) are the same parts as on the ALT-386SX.[1][2] Unplug the mains lead and remove the pack before opening the case; the supply's heatsinks are live in operation. See the safety notes.

Memory and BIOS

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Amstrad ALT-286 underside with memory cover removed
Memory bay with four SIMMs, the BIOS EPROMs and an empty socket

The memory bay under the base cover holds the SIMMs, the two BIOS EPROMs and an empty socket. On the BnF's machine the four SIMMs carry Panasonic MN41C4256SJ-08 and MN41256AJ-08 chips, and the EPROMs are labelled "286(L) 41008-2" and with a Phoenix Technologies label.[2] The parts list gives the ALT286's DRAMs as MN41C4256SJ-08 (U901), µPD424256LA-80 (U902) and MN41256AJ-08 (U903), and its BIOS EPROMs as TMS27C256 at U302 and U303.[1] The ALT286 has its own co-processor board (PCB2, part 270351FTZ) and DRAM board (PCB5, part 270352); the ALT-386SX uses a combined co-processor and memory board.[1]

Amstrad's specification gives one wait state for the ALT286, or none with 60 ns DRAM.[1] The memory-size and clock switches are described in the ALT-386SX guide; that table was recorded on an ALT-386SX, so check the settings against the memory actually fitted.

Hard disk

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Amstrad fitted a 20 MB voice-coil disk with 28 ms access to the ALT286 (part 270483-20).[1] The owner of one ALT-286 found it would not boot because the disk had failed, and replaced it.[3] See Hard Drive Maintenance and Repair and the drive notes in the ALT-386SX guide.

Backup battery

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The same owner expected a flat backup battery to be the cause of the boot failure and found the battery recovered after recharging.[3] The battery is rechargeable and can leak onto the board; replacement and leak repair are covered in the ALT-386SX guide.

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References

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  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Amstrad plc, ALT286 / ALT386SX Laptop Computer V.FTZ Service Manual. Described at Amstrad ALT-286 / ALT-386SX Service Manual. Specification and safety tests p. 2; co-processor PCB pp. 6–7; electrical parts list p. 10; cabinet parts list p. 12; ALT286 main PCB pp. 14–15; ALT286 schematics pp. 19–21.
  2. ↑ 2.0 2.1 2.2 Bibliothèque nationale de France, Collection Charles Cros no. 1008, ALT-286 serial N42016595, photographs 15, 18 and 19 of 26, on Wikimedia Commons. Retrieved 2026-10-01. The rating label, the memory bay and the BAT-1 battery label.
  3. ↑ 3.0 3.1 "1989 Amstrad ALT-286 Laptop Reburbish / HDD Replacement / PC Speaker Repair" (video, 2017), archived at archive.org, description. Retrieved 2026-10-01.


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