Amstrad PC3286 Troubleshooting Guide
Fault-finding for the Amstrad PC3286, whose main board is shared with the Amstrad PC3386SX. The start-up sequence, the self-test dots and Amstrad's full lists of non-fatal and fatal messages are common to the three Generation 3 models and are set out in the Amstrad PC3086 Troubleshooting Guide; the sections below cover what is particular to the 286 and 386SX board. Links, SIMMs and switches are described in the Amstrad PC3286 Maintenance Guide.[1] Amstrad's service manual, with the schematics, has not been published online, so there are no official test points or voltage tables.[2]
Start-up messages
[edit | edit source]With no prepared hard disk, a working PC3286 or PC3386SX finishes its self test with:[3]
AMSTRAD PC3286 (or PC3386SX) (V2.0) (c) 1990 AMSTRAD plc 640Kb of BASE memory Insert a system disk into Drive A Press <F1> to change floppy type or press any other key to continue
| Message | Cause | Action |
|---|---|---|
| Please set user options-Run Setup | CMOS RAM contents invalid, for example after a new clock chip | Boot from the system disk and run SETUP[1] |
| Please check keyboard | Key held down or keyboard not connected | Clear the keyboard and check the plug[3] |
| Insert a SYSTEM disk into drive A, on a machine with a hard disk | The CMOS RAM does not hold the right hard disk type | Run SETUP and set the drive type (type 17 for Amstrad's 40 MB drive in the manual's example)[1][3] |
| Error: Faulty CACHE RAM | Cache chips faulty or wrongly fitted | Check the cache chips and that LK37 and LK42 are in for 35 ns chips; DEVICE CACHE OFF switches the cache off[1][4][5]
|
| Error: Faulty SYSTEM RAM, or parity error | SIMM fault, or SIMMs that do not match the links | Check the pairing rules and links LK19 to LK22; set LK23 and LK24 for the slowest SIMM[1][4] |
| WARNING: CMOS battery failed | Battery inside the clock module exhausted | Replace the clock module (see the PC3086 guide)[1][6] |
Setup and speed
[edit | edit source]- Amstrad's manual runs SETUP (version 2.0) from the PC's own system disk at the DOS prompt. Cliff Lawson of Amstrad gives Ctrl-Alt-S at the DOS prompt for the 3000 and 4000 series.[3][7]
- An owner who could not get Ctrl-Alt-S to work used the SETUP.EXE that Lawson provided for the older 1000 and 2000 series. It reported the machine as a PC2286 and offered no speed above 12 MHz, although a benchmark suggested the processor was running faster. Use the SETUP from the PC3286 or PC3386SX system disk.[8][7]
DEVICE SPEEDwith no number returns the speed as an errorlevel (16 for a 16 MHz 80286; 100 is added for an 80386SX).DEVICE SPEED nsets a lower speed, down to 4 MHz.[5]- A copy-protected game that rejects its own disk at full speed may load with
DEVICE SPEED 5 /F, which slows the processor only during floppy access.[5]
No display or no POST
[edit | edit source]A PC3286 described on Vogons in 2024 powered up but would not POST. The owner had measured the supply voltages as correct and had replaced the Dallas clock module with a Necroware nwX287, without effect. Another member suggested setting video DIP switches 1, 2 and 4 on, the setting Lawson recommends. The thread recorded no fix.[9][7] The owner's list of link positions on that board shows LK25, LK26 and LK47 on pins 2 and 3 and LK501 on pins 1 and 2, where Amstrad's table gives pins 1 and 2 for LK25, LK26 and LK47 and pins 2 and 3 for LK501 on a PC3286; whether this was a board revision or a fault was not established.[9][10]
Checks that follow from Amstrad's documentation:
- Count the self-test dots under "Please wait." to see how far the test got (see the PC3086 guide).[1][11]
- Check the video DIP switches; switch 1 on suits only a multi-frequency monitor, and switch 4 selects an 8 or 16-bit interface to the VGA.[12]
- To rule out the built-in VGA, remove LK28 and fit a video card in a slot.[10]
- Reseat the processor daughterboard and the SIMMs, and compare every link with Amstrad's table.[13][10]
Mouse and expansion cards
[edit | edit source]- The Amstrad mouse adaptor uses IRQ 5 by default (LK9); LK10, LK11 and LK12 move it to IRQ 4, 9 or 3. A network card or other adaptor on the same interrupt will conflict with it.[10]
- For a serial mouse, remove LK30 to disable the mouse adaptor; Lawson notes that the /C switch of MOUSE.COM does not do this on its own.[14]
- Free interrupts in Amstrad GmbH's table are IRQ 3, 10, 11, 12 and 15.[11]
- With a LIM expanded memory card fitted, turn off the expansion-bus cache with LK36, not with the DEVICE command.[5][10]
Video
[edit | edit source]| Symptom | Action |
|---|---|
| Software runs but the display is wrong | Turn DIP switch 2 off (AT mode), or try MODE MONO or MODE CO80; use DEVICE DISPLAY for CGA, MDA or Hercules emulation[12][5]
|
| Display or compatibility problems after switch 4 has been set on | Set it off again; Amstrad provides the 8-bit interface, in which the VGA behaves electrically like an XT card, for compatibility[12] |
| A second, monochrome adaptor is to be used | Only an MDA or Hercules card is allowed with the built-in VGA, and only in AT mode[12] |
Final notes
[edit | edit source]- For Windows/386, Novell, UNIX and OS/2, Amstrad recommends 640 KB of base memory and all the rest as extended memory.[15]
- See also Capacitor Failure Symptoms and Hard Drive Maintenance and Repair.
References
[edit | edit source]- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Amstrad plc, User Manual and MS-DOS Guide for the PC3086, PC3286 and PC3386SX, 2nd ed. (1990), pp. 14-1 to 14-3. Non-fatal and fatal hardware error messages.
- ↑ Centre for Computing History, "Amstrad PC3086 PC3286 PC3386SX Colour Personal Computers Service Manual" (CH27476): 53-page service manual with schematics and wiring diagrams, reference SM-PC3000. Retrieved 2026-10-02.
- ↑ 3.0 3.1 3.2 3.3 Amstrad plc, User Manual and MS-DOS Guide for the PC3086, PC3286 and PC3386SX, 2nd ed. (1990), pp. 3-7 to 3-15. Voltage selector, power switch, the "Please wait." self-test dots, start-up messages and BIOS versions, and the SETUP program for the PC3286 and PC3386SX.
- ↑ 4.0 4.1 Amstrad plc, User Manual and MS-DOS Guide for the PC3086, PC3286 and PC3386SX, 2nd ed. (1990), pp. 8-6 to 8-10. Memory cache, SIMM upgrades, memory size and DRAM speed links, cache speed links.
- ↑ 5.0 5.1 5.2 5.3 5.4 Amstrad plc, User Manual and MS-DOS Guide for the PC3086, PC3286 and PC3386SX, 2nd ed. (1990), pp. 4-2 to 4-18. The DEVICE command: display, floppy drive, cache, memory map and processor speed settings.
- ↑ Amstrad plc, User Manual and MS-DOS Guide for the PC3086, PC3286 and PC3386SX, 2nd ed. (1990), pp. 13-2 to 13-4. Transporting a hard disk PC, PARK.COM, and replacing the CMOS RAM.
- ↑ 7.0 7.1 7.2 Cliff Lawson (Amstrad plc), "Older AT PCs" (atpcs.htm), from his Amstrad support pages at web.ukonline.co.uk/cliff.lawson, as preserved at freetimeweb.nl. Retrieved 2026-10-02. SETUP on the 3xxx and 4xxx series, the BIOS 2.xx of the 3xxx series, memory links for the 3286, 3386SX and 4386SX, video DIP switches and option links.
- ↑ Vogons forum, "Amstrad 286 wrong CPU speed", AndalusianRG and others, October 2021. Retrieved 2026-10-02. A PC3286 whose borrowed SETUP program offered only 12 MHz.
- ↑ 9.0 9.1 Vogons forum, "Amstrad 3286", tarasque and others, September 2024 to February 2025. Retrieved 2026-10-02. A PC3286 that would not POST after the Dallas clock module was replaced with a Necroware nwX287; the owner's list of option link positions; photographs (CC BY 4.0).
- ↑ 10.0 10.1 10.2 10.3 10.4 Amstrad plc, User Manual and MS-DOS Guide for the PC3086, PC3286 and PC3386SX, 2nd ed. (1990), pp. 11-1 to 11-10. Expansion slots, opening the lid, and the option link tables for the PC3086 and for the PC3286 and PC3386SX.
- ↑ 11.0 11.1 "AMS-Line: Der Informationsdienst der Firma AMSTRAD", Amstrad PC International (page header CPC), August/September 1991, p. 7. Internet Archive. Retrieved 2026-10-02. Amstrad GmbH's column: the meaning of the start-up dots, the PC4386SX BIOS indicator, and the interrupt and I/O address tables of the PC3086, PC3286 and PC3386SX.
- ↑ 12.0 12.1 12.2 12.3 Amstrad plc, User Manual and MS-DOS Guide for the PC3086, PC3286 and PC3386SX, 2nd ed. (1990), pp. 6-5 to 6-15. PS/2 and AT video modes, disabling the built-in VGA, links 901 and 902, and the video DIP switches.
- ↑ Amstrad plc, User Manual and MS-DOS Guide for the PC3086, PC3286 and PC3386SX, 2nd ed. (1990), pp. 7-1 to 7-7. Processor speeds, fitting an 8087, 80287 or 80387SX co-processor, and opening the system unit.
- ↑ Cliff Lawson (Amstrad plc), "General notes on Amstrad PCs" (general.htm), as preserved at freetimeweb.nl. Retrieved 2026-10-02. Amstrad's proprietary keyboard and mouse interfaces up to the 4386, PS/2-compatible ones from the 5xxx series, and a summary specification of each PC.
- ↑ Amstrad plc, User Manual and MS-DOS Guide for the PC3086, PC3286 and PC3386SX, 2nd ed. (1990), pp. 1-2 to 1-4. Specifications of the three models and memory configuration.