Amstrad PC2386 Troubleshooting Guide
Amstrad's service manual for the Amstrad PC2386 has no fault-finding charts, and its notes to engineers rule out component-level repair of the main CPU board and the drives; the supply and the monitors were repaired at component level.[1] The faults below are from owners' reports. Procedures are in the Amstrad PC2386 Maintenance Guide.
Power supply
[edit | edit source]| Symptom | What was found | Action |
|---|---|---|
| Supply dead after long storage | Leaking electrolytics and a faulty optocoupler; after replacing them the supply held its voltages under a test load[2] | Recap the supply from the parts list and test the optocouplers, a TLP732 (Q602) and a TLP741G (Q603)[1] |
| Fan turns for a moment, then the supply stops | On the PC2286, whose supply uses the same IC and capacitor positions, the owner found a corroded track and resistor at R658 and a leaking 3300 µF capacitor (C625), and traced the shutdown to wrong voltages at the over-voltage detector IC602; the fault had not been cleared when the report ended[3] | Measure the inputs and outputs of IC602 (MB3761M) and check the electrolytics; see the Amstrad PC2286 Troubleshooting Guide |
The supply's ICs are IC601 STK7458, IC602 MB3761M, IC603 LA6324, IC604 BA707, IC605 BA6993, IC606 AN7905F and IC607 AN7912T, and the fuse resistor R602 is 4.7 kΩ.[1] The supply schematic, page 48 (hosted separately), names IC603 (LA6324) as the error amplifiers, with VR604 setting +5 V, and IC605 (BA6993) as the +5 V and +12 V overload protection comparators; Q616 is the over-voltage protection and VR606 the +12 V overload adjustment. It prints these DC voltages at the pins of the switching regulator IC601 (STK7458):[1]
| Pin | 1 (STR) | 3 (V7) | 4 (VCC) | 5 (GND) | 6 (CT) | 7 (RT) | 8 (RFF) | 9 | 10 (SES) | 11 | 12 (DT) | 14 (S) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Volts | 306.0 | 13.3 | 15.1 | 0.0 | 1.6 | 3.7 | 5.0 | 9.9 | 2.5 | 3.1 | 1.4 | 0.03 |
The waveform at the switching transistor's drain is shown as 440 V peak to peak. The current-sense resistor in the source lead is R609, 0.22 Ω 5 W.[1][1]
Start-up
[edit | edit source]- Stripes on the screen from the moment power is applied, a single flicker of the keyboard LEDs, and nothing more: reported on a PC2386 after it had run for some hours following a supply repair. The owner had removed all cards and tried a second set of SIMMs; voltages and clocks were present and the reset line went high briefly then low. Others have linked stripes on this machine to RAM faults, but the report was not resolved.[2]
- The board does not output POST codes to an ISA diagnostic card.[2]
- BIOS settings lost: the AA cells on top of the base unit are flat or their lead is disconnected.[4][5]
Keyboard
[edit | edit source]The computer beeps and reports a keyboard problem when the keyboard is missing or faulty. Only an Amstrad keyboard of the right type works: the socket is a 5-pin DIN of the 270-degree pattern, and keyboards for other Amstrad models can look the same.[6]
- Keyboard error with the PC2386 keyboard fitted: clean the membrane connectors and separate the two membrane sheets; one owner's keyboard worked again after this.[6]
- A keyboard labelled 7220000824 with an MK0006A board, sold with a PC2386, did not work; its board had a small light blue component where the PC2386 keyboard has a wire link.[6]
- Owners have discussed a HIDman adapter for a modern keyboard; it had not been tested on a PC2386 at the time of the report.[6]
Drives
[edit | edit source]- Floppy drive seeks but will not read a disc: one owner found that drives set to ID 0 from other machines would not work, while the original Citizen OSDA-46 worked in another computer. The cable is straight, so the drive must be set to ID 0. The report is unresolved.[7]
- Hard disc: the original drive is a Seagate ST277R, the model that was recalled from the PC2386 and fitted with Western Digital controllers.[1][4] Copy off anything wanted from a working original drive. See Hard Drive Maintenance and Repair.
Related pages
[edit | edit source]- Amstrad PC2386 · Amstrad PC2386 Maintenance Guide · Amstrad PC2386 Capacitor Replacement Guide
- Amstrad PC2286 Troubleshooting Guide · Amstrad PC2086 Troubleshooting Guide
- Capacitor Failure Symptoms · Floppy Drive Repair
References
[edit | edit source]- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Amstrad plc, PC2386-65 Personal Computer Service Manual. Hosted as File:Amstrad PC 2386 Service Manual.pdf, described at Amstrad PC 2386 Service Manual. Notes to engineers p. 2; alignment instructions p. 3; schematics pp. 11–43; electrical parts list pp. 44–45. The supply schematic (p. 48) is hosted separately as File:Amstrad PC 2386 Service Manual pages 47-48.pdf.
- ↑ 2.0 2.1 2.2 Audigy, "Help diagnosing fault with my childhood Amstrad PC2386/65", VOGONS, 15 November 2025. Retrieved 2026-10-02. Community report: the supply repaired by replacing leaking capacitors and a faulty optocoupler; a later fault with stripes on the screen from switch-on, the keyboard LEDs flickering once, the reset line going high briefly then low, no change with another set of SIMMs; unresolved.
- ↑ VintageVic, acgs, GiGaBiTe and others, "Amstrad PC 2286", Vintage Computer Federation Forums, April–October 2022. Retrieved 2026-10-02. Community repair of a PC2286 supply that started its fan for a second then stopped: corrosion, a broken track and resistor R658, leaking C625 and C628, the MB3761 voltage detector's input and output voltages, replaced ICs, and suspicion of the transformer.
- ↑ 4.0 4.1 Wikipedia, "Amstrad PC2286" (revision 1353136875). Retrieved 2026-10-02. BIOS settings backed by four AA cells on top of the base unit; the ST277R hard disc problem of the PC2386.
- ↑ caver99, "amstrad 2386-65", VOGONS, 19 November 2023. Retrieved 2026-10-02. Community report: a PC2386-65 working except for its battery-backed BIOS settings.
- ↑ 6.0 6.1 6.2 6.3 Kubik, PC Hoarder Patrol, Tomek TRV and rasteri, "Amstrad PC2386 keyboard", VOGONS, June 2020 – November 2025. Retrieved 2026-10-02. Community reports: the 270-degree 5-pin DIN socket, keyboard types 7220000503 and 7220000824 with MK0006A boards, a keyboard repaired by separating its membrane layers, an untested HIDman adapter.
- ↑ Tomek TRV, "Amstrad PC2386 floppy drive problem", VOGONS, 3 December 2025. Retrieved 2026-10-02. Community report: floppy drive problems on a PC2386 with a straight cable and ID 0 drives.