Amstrad PC3386SX Capacitor Replacement Guide
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The Amstrad PC3386SX differs from the Amstrad PC3286 in its processor board. Its main board, case and 145 W supply are the same as the PC3286's, so those parts are covered by the Amstrad PC3286 Capacitor Replacement Guide and the Amstrad PC3086 Capacitor Replacement Guide.[1][2] Amstrad's service manual for the range (reference SM-PC3000), which would give the values, has not been published online; the Centre for Computing History holds a copy as exhibit CH27476.[3]
The 386SX processor board
[edit | edit source]The board is printed "Amstrad plc 1990", 2600-025P-3 and MS0196A. It holds the Intel processor, a PLCC socket (IC721) for the 80387SX co-processor, link LK720 at the top edge, and the connectors PL720 to PL724 that join it to the main board.[4][5] The Centre for Computing History catalogues the board as a 386 daughterboard for the PC3286; Amstrad's manual places link 720 on the PC3386SX daughterboard, which matches the LK720 on this board.[4][1]
| Position | Type | Value |
|---|---|---|
| C733 | Radial electrolytic in a blue sleeve, lower left corner beside IC726 | Not legible in the photograph |
| C720 upwards | Small dipped capacitors around the processor, the socket and the logic ICs | Not legible |
Source: the Centre for Computing History photograph.[4]
C733 is the only electrolytic visible on the board. Read its value and voltage from the sleeve before removing it, and note which lead the sleeve's stripe is on and how the polarity is marked on the board.[4]
Link LK720
[edit | edit source]Amstrad's link table gives LK720 as "PC3386SX - Enable Pipelining" with the jumper in and "Disable Pipelining" with it out. Note its position before the board comes out and put the jumper back the same way.[1] The full link table is in the Amstrad PC3386SX Maintenance Guide.
Procedure
[edit | edit source]- Unplug the mains lead and the monitor's power lead, and open the case as described in the PC3086 Maintenance Guide.[5]
- Remove the processor board from the main board as shown on p. 7-6 of the user manual.[5]
- Photograph both sides of the board and note the position of the LK720 jumper.
- Replace C733 with a part of the same capacitance and the same or a higher voltage rating, fitted the same way round.
- Refit the board, making sure every pin of the connectors PL720 to PL724 is in its socket, then close the case.
For the supply and the main board, follow the PC3086 and PC3286 procedures.
After the recap
[edit | edit source]At switch-on the PC3386SX prints "Please wait." with a dot after each test, then "AMSTRAD PC3386SX (V2.0)" and the base memory.[6] If it stops before the start-up message after the processor board has been out, check the board's seating and the LK720 jumper first, then use the Amstrad PC3386SX Troubleshooting Guide.
Related pages
[edit | edit source]- Amstrad PC3386SX · Amstrad PC3386SX Maintenance Guide · Amstrad PC3386SX Troubleshooting Guide
- Amstrad PC3286 Capacitor Replacement Guide · Amstrad PC3086 Capacitor Replacement Guide
- Capacitor Failure Symptoms · Recommended Tools
References
[edit | edit source]- ↑ 1.0 1.1 1.2 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 links; p. 11-7 draws one main board for the PC3286 and PC3386SX and shows the PC3386SX daughterboard with link 720; p. 11-8 gives link 720 as enable (in) or disable (out) pipelining.
- ↑ Thomas Kallay, "Big Brother: AMSTRADs Flaggschiff der Generation 3: der PC3386 SX", Amstrad PC International, February/March 1991, pp. 41–42. Internet Archive. Retrieved 2026-10-21. Specification table of the PC3386SX: 80386SX at 20 MHz, 80387SX socket on the processor card, 145 W supply, 426 × 135 × 389 mm; test machine with a 100 MB Conner hard disk.
- ↑ Centre for Computing History, "Amstrad PC3086 PC3286 PC3386SX Colour Personal Computers Service Manual" (CH27476): 53-page service manual with full schematic diagrams and wiring diagrams, reference SM-PC3000, published 1990. Retrieved 2026-10-21.
- ↑ 4.0 4.1 4.2 4.3 Centre for Computing History, "Amstrad PC3286 386 Daughterboard" (CH42247), 1990, with a photograph of the component side, hosted here as File:Amstrad PC3386SX processor board MS0196A (Centre for Computing History).jpg. The museum catalogues it against the PC3286. Retrieved 2026-10-21.
- ↑ 5.0 5.1 5.2 Amstrad plc, User Manual and MS-DOS Guide for the PC3086, PC3286 and PC3386SX, 2nd ed. (1990), pp. 7-2 to 7-6. The co-processor socket on the PC3286 and PC3386SX daughterboard, opening the system unit, and removing the PC3386SX daughterboard (p. 7-6).
- ↑ Amstrad plc, User Manual and MS-DOS Guide for the PC3086, PC3286 and PC3386SX, 2nd ed. (1990), pp. 3-7 to 3-9. The voltage selector, the "Please wait." self-test dots and the PC3286 and PC3386SX start-up message.