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Amstrad PC2386 Capacitor Replacement Guide

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Amstrad PC2386 main PCB layout
PC2386 main board, top view (service manual p. 4)

The electrolytic capacitors in the Amstrad PC2386's power supply are listed with their values, voltages and part numbers on page 45 of Amstrad's service manual. The supply schematic, page 48, is missing from the main scan and is hosted separately with page 47. The parts list gives no capacitors for the main board, memory board or expansion board, so read the markings on any capacitor there before replacing it.[1] An owner who revived a PC2386 found leaking capacitors in the supply, together with a faulty optocoupler.[2]

Safety

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Warning: the supply runs from the mains. C601 (330 µF 400 V) holds a dangerous charge after unplugging.

  • Unplug the machine, remove the supply and discharge C601 through a suitable resistor before working on it.[1]
  • After the work, Amstrad's safety tests are a 1.5 kV RMS flash test for 3 s, insulation above 4 MΩ and mains-lead earth continuity of no more than 0.5 Ω.[1]

Supply electrolytic capacitors

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PC2386 supply electrolytics (service manual p. 45)
Ref Value Voltage Amstrad part no.
C617 1 µF 50 V 20062
C638 2.2 µF 50 V 175114
C607 3.3 µF 50 V 176346
C637 10 µF 16 V 20148
C633 10 µF 25 V 20037
C621 47 µF 16 V 20027
C622 47 µF 25 V 151640
C610 47 µF 50 V 176348
C639 100 µF 10 V 20028
C632 100 µF 16 V 20028
C635, C636 100 µF 50 V 176320
C630 330 µF 35 V 176321
C623 330 µF 63 V 176756
C601 330 µF 400 V 176757
C629, C640 1000 µF 16 V 1422158
C625 3300 µF 35 V 171655
C627, C628 6800 µF 16 V 176758

C639 and C632 share part number 20028 although the list prints 10 V for one and 16 V for the other; fit 16 V parts in both.[1] The supply's film capacitors are C631 and C634 (0.033 µF polyester), C614 and C615 (0.1 µF polyester) and C602 (0.1 µF 250 V AC, metal plastic).[1]

Agreement with the PC2286

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An owner repairing a PC2286 supply read these values from his board: C625 3300 µF 35 V, C627 and C628 6800 µF 16 V, C629 and C640 1000 µF 16 V, C630 330 µF 35 V, C623 330 µF 63 V and C635 and C636 100 µF 50 V, with film capacitors C614 and C615 at 0.1 µF and C631 and C634 at 0.033 µF. His list of the supply's ICs (STK7458, MB3761, LA6324, BA707, BA6993, AN7905F, AN7912T) is also the PC2386's.[3][1] Every value matches the PC2386 list, which suggests the two machines share a supply design, but compare the board in your machine with the list before ordering.

Procedure

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  1. Remove the supply from the system unit and discharge C601.
  2. Photograph the board and note each capacitor's value, voltage and polarity.
  3. Replace the electrolytics. Check the legs and the board under the large output capacitors (C625, C627, C628) for electrolyte; on one PC2286 the 3300 µF C625 had leaked, and on another both 6800 µF capacitors.[3][4]
  4. Test the optocouplers Q602 (TLP732) and Q603 (TLP741G) while the board is out.[1][2]
  5. Refit the supply, connect the main board and a drive, and set +5 V with VR604 to 5.00 V ±0.05 V at test point A and +12 V with VR603 to 12.00 V ±0.05 V at test point B.[1]
  6. Set the primary protection: turn VR601 anticlockwise until the protection starts to cut in, then back a little.[1]
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References

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  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 Amstrad plc, PC2386-65 Personal Computer Service Manual. Hosted as File:Amstrad PC 2386 Service Manual.pdf, described at Amstrad PC 2386 Service Manual. Safety tests p. 2; alignment instructions p. 3; electrical parts list pp. 44–45 (supply ICs p. 44; transistors, diodes and capacitors p. 45); power supply schematic p. 48, hosted as File:Amstrad PC 2386 Service Manual pages 47-48.pdf.
  2. ↑ 2.0 2.1 Audigy, "Help diagnosing fault with my childhood Amstrad PC2386/65", VOGONS, 15 November 2025. Retrieved 2026-10-02. Community report: the failed supply repaired by replacing leaking capacitors and a faulty optocoupler, then stable under a test load.
  3. ↑ 3.0 3.1 VintageVic and acgs, "Amstrad PC 2286", Vintage Computer Federation Forums, April–June 2022. Retrieved 2026-10-02. Community repair: the PC2286 supply's electrolytics C623, C625, C627–C630, C635, C636 and C640 as read from the board and replaced, its film capacitors C614, C615, C631 and C634, and its IC list.
  4. ↑ ilpan, reply of 7 March 2024 in "Amstrad PC 2286", Vintage Computer Federation Forums. Retrieved 2026-10-11. Community report: a PC2286 supply with corrosion from its two leaking 6800 µF 16 V secondary capacitors; all capacitors replaced without curing the fault.


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