Amstrad CPC 464 Capacitor Replacement Guide
The Amstrad CPC 464 main board changed several times in production, and the capacitors changed with it. Amstrad's service manual covers the original board, with the 20RA043 gate array. Its electrical parts list on page 17 gives fourteen aluminium electrolytic capacitors, twelve of them on the cassette PCB.[1] Amstrad's amendment manual covers the later Z70374 (MC0044A) board with the 40010 gate array. Its parts list gives only ICs, semiconductors and connectors and refers back to the original manual for everything else, but its circuit diagrams show the capacitors, and they differ on the main board.[2][3] Read the silkscreened board number before ordering parts.
Safety
[edit | edit source]The CPC 464 has no mains supply of its own: it takes 5 V DC from the CTM640 or GT64 monitor.[4] The monitors contain the mains supply and a CRT, and hold a dangerous charge after switch-off. Before working on a monitor, read CRT Discharge Procedure.
Electrolytic capacitors
[edit | edit source]| Value | Circuit reference | Board | Amstrad part no. |
|---|---|---|---|
| 470 µF / 10 V | C322 | Cassette PCB | 1400248 |
| 100 µF / 16 V | C315 | Cassette PCB | 20028 |
| 100 µF / 10 V | C301, C304 | Cassette PCB | 20028 |
| 47 µF / 10 V | C101, C102 | Main PCB | 1400244 |
| 47 µF / 10 V | C303, C306 | Cassette PCB | 1400244 |
| 22 µF / 10 V | C308, C318 | Cassette PCB | 20025 |
| 10 µF / 16 V | C324 | Cassette PCB | 20024 |
| 1 µF / 50 V | C309, C311 | Cassette PCB | 20062 |
| 1 µF / 50 V, non-polarised | C314 | Cassette PCB | 20062 |
These are the fourteen electrolytics of the original board.[1] Only C101 and C102 are on the main PCB; the other twelve are on the cassette PCB (PCB301), shown in the drawing above.[1] Amstrad gives the same part number, 20028, for the 10 V and 16 V 100 µF parts.
The parts list and the circuit diagrams give 10 V for C101, C102, C308 and C318, but the board drawings mark all four 16 V: C101 and C102 on the main PCB drawing, C308 and C318 on the cassette PCB drawing.[5][6] A 16 V part suits either. The parts list gives C314 the same part number as C309 and C311, but both cassette drawings mark it non-polarised (N.P on the circuit diagram, BP on the board drawing), so fit a bipolar 1 µF part there.[5][6]
Later boards
[edit | edit source]On the Z70374 (MC0044A) board in the amendment manual, C101, 47 µF 16 V across the 5 V input, is the only electrolytic on the main board. C102 there is a 0.1 µF capacitor in a reset circuit built round IC125 (TC74HCU04AP), R101 (3.3 MΩ) and R111 (1 MΩ), and the 0.1 µF decoupling capacitors run from C104 to C129. The amendment's tape PCB (PCB301, MT0001F) has the same twelve electrolytics with the same values as the original cassette PCB, and also marks C314 non-polarised.[3]
Retroleum's CPC 464 capacitor listing, a kit seller's list, agrees on the main board: two 47 µF capacitors on the Z70100 board, at C101 and C102, and one, at C101, on the Z70200 and Z70375 boards.[7] Neither Amstrad manual covers the cost-down board; read the values off the board itself.
Ceramic capacitors
[edit | edit source]Ceramic capacitors do not dry out the way aluminium electrolytics do and are not part of a routine recap. They are listed for identification.[1]
| Value | Circuit reference | Amstrad part no. |
|---|---|---|
| 0.1 µF / 25 V | C104–C128 | 24020 |
| 0.022 µF / 50 V | C317, C319, C323 | 24013 |
| 0.001 µF / 50 V | C320 | 24007 |
| 470 pF / 50 V | C307 | 24004 |
| 270 pF / 50 V | C313 | 170126 |
| 220 pF / 50 V | C310 | 400107 |
| 200 pF / 50 V | C321 | 400107 |
| 33 pF / 50 V | C316 | 150514 |
On the original board C104 decouples the gate array and C105–C128 decouple the rest of the main board. The circuit diagram also shows three ceramics in the 16 MHz clock oscillator that the parts list omits: C103 (22 pF NPO), C129 (100 pF) and C130 (68 pF).[6]
Polystyrene capacitors
[edit | edit source]| Value | Circuit reference | Amstrad part no. |
|---|---|---|
| 0.068 µF | C302 | 170129 |
| 0.01 µF | C305 | 170128 |
| 0.001 µF | C312 | 170217 |
Before you start
[edit | edit source]- Amstrad's fault charts name no capacitor. For a machine whose power LED does not light they start at the monitor's mains fuse and the 5 V on the lead from the monitor, then the computer's connectors, soldered joints and switch; for tapes that will not load, at the deck connections, the head and its alignment, the key switches and the motor relay.[8] Work through those before replacing capacitors.
- Read each value and polarity off your own board before ordering. Amstrad part numbers are given for cross-reference only. C101 is connected directly across the 5 V input from the monitor.[6]
- The cassette PCB also carries the tape motor relay, the LA4140 audio amplifier and the LA6324 op-amp (IC301, IC302).[1] Unplug the tape head and motor leads with care.
- See Capacitor Failure Symptoms for recognising a failed part and Recommended Tools for the workshop kit.
Related pages
[edit | edit source]- Amstrad CPC 464 · Amstrad CPC 464 Maintenance Guide · Amstrad CPC 464 Troubleshooting Guide
- Amstrad CPC 664 Capacitor Replacement Guide
- Amstrad CPC 464 Service Manual
References
[edit | edit source]- ↑ 1.0 1.1 1.2 1.3 1.4 Amstrad Consumer Electronics plc, CPC464 Micro Computer / CTM640 Colour Monitor / GT64 Green Monitor Service Manual, p. 17 "CPC464 Electrical Parts List" and p. 7 "CPC464 Cassette PCB". Described at Amstrad CPC 464 Service Manual.
- ↑ Amstrad plc, CPC464 / CPC6128 / GT65 / CTM644 / MP3 / CT1 Amendment Service Manual, p. 3 "CPC464 Electrical Parts List". Described at Amstrad CPC 464 / CPC 6128 / GT65 / CTM644 / MP3 / CT1 Service Manual Amendment.
- ↑ 3.0 3.1 Amstrad plc, CPC464 / CPC6128 / GT65 / CTM644 / MP3 / CT1 Amendment Service Manual, p. 5 "CPC464 CPU P.C.B. (Top View)" (board marked MC0044A, PTNO. Z70374), p. 7 "CPC464 CPU/PIO Section Chassis Schematic Diagram" (C101 16V47, C102 0.1, C104–C129 0.1) and p. 9 "CPC464 Tape Amp Section Chassis Schematic Diagram" (PCB301 MT0001F). Described at Amstrad CPC 464 / CPC 6128 / GT65 / CTM644 / MP3 / CT1 Service Manual Amendment.
- ↑ Amstrad Consumer Electronics plc, CPC464 Micro Computer / CTM640 Colour Monitor / GT64 Green Monitor Service Manual, p. 2 "Technical Specification". Described at Amstrad CPC 464 Service Manual.
- ↑ 5.0 5.1 Amstrad Consumer Electronics plc, CPC464 Micro Computer / CTM640 Colour Monitor / GT64 Green Monitor Service Manual, pp. 12–14 "CPC464 Main PCB" (C101 and C102 marked 16V47) and p. 7 "CPC464 Cassette PCB" (C308 and C318 marked 16V22, C314 marked 50V1 BP). Described at Amstrad CPC 464 Service Manual.
- ↑ 6.0 6.1 6.2 6.3 Amstrad Consumer Electronics plc, CPC464 Micro Computer / CTM640 Colour Monitor / GT64 Green Monitor Service Manual, pp. 15–16 "CPC464 Circuit Diagram" (C101 and C102 10V47; C103, C129 and C130 in the clock oscillator) and p. 8 "CPC464 Cassette Deck Circuit Diagram" (C314 N.P 50V1). Described at Amstrad CPC 464 Service Manual.
- ↑ Retroleum, "Capacitors for the Amstrad CPC 464" (accessed 2026-10-11): kit seller's listing, 47 µF 16 V "Z70100, Z70200", two for Z70100 at C101 and C102 and one for Z70200 at C101; 47 µF for C101 on Z70375.
- ↑ Amstrad Consumer Electronics plc, CPC464 Micro Computer / CTM640 Colour Monitor / GT64 Green Monitor Service Manual, p. 9 "CPC464 Basic Hardware Analysis" and p. 10 "Cassette & Software Analysis". Described at Amstrad CPC 464 Service Manual.