Amstrad CPC 664 Capacitor Replacement Guide
The Amstrad CPC 664 has twelve aluminium electrolytic capacitors on its main board, in four values. The values, circuit references and Amstrad part numbers below are from the CPC664 electrical parts list on page 21 of Amstrad's service manual.[1]
Safety
[edit | edit source]The CPC 664 has no mains supply of its own: it takes 5 V from the CTM644 or GT65 monitor, and 12 V for the disc drive through a separate lead.[2] 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 | Amstrad part no. |
|---|---|---|
| 100 µF / 16 V | C315 | 20028 |
| 100 µF / 10 V | C301, C304 | 20028 |
| 47 µF / 10 V | C129, C303, C306 | 1400244 |
| 22 µF / 10 V | C308 | 20025 |
| 1 µF / 50 V | C309, C311, C316, C317 | 20062 |
| 1 µF / 50 V, non-polarised | C314 | 20062 |
C129, 47 µF 10 V, sits across the 5 V supply beside the 0.1 µF decoupling capacitors C101–C128. The parts list gives C314 the same part number as the other 1 µF parts, but the cassette control circuit diagram marks it non-polarised (NP), so fit a bipolar part there.[3]
The 664 has no cassette deck, but it keeps the cassette interface for an external recorder: the LA4140 and LA6358S (IC301, IC302; the parts list prints the second as LA63585), the motor relay RY301 and the 5-pin DIN socket J302.[1][3] That is why most of the electrolytics carry 300-series references.
Ceramic capacitors
[edit | edit source]Ceramic capacitors are not part of a routine recap. They are listed for identification.[1]
| Value | Circuit reference | Amstrad part no. |
|---|---|---|
| 0.1 µF / 16 V | C101–C128, C201–C213 | 24020 |
| 470 pF / 50 V | C307 | 24004 |
| 270 pF / 50 V | C313 | 900400 |
| 220 pF / 50 V | C133–C135, C310 | 400107 |
| 68 pF / 50 V | C130, C131 | 170826 |
| 47 pF / 50 V | C132 | 24002 |
Polystyrene capacitors
[edit | edit source]| Value | Circuit reference | Amstrad part no. |
|---|---|---|
| 0.1 µF | C319 | 170852 |
| 0.068 µF | C302 | 170219 |
| 0.047 µF | C318 | 1409178 |
| 0.01 µF | C305 | 170218 |
| 0.001 µF | C312 | 170217 |
The disc drive's own board
[edit | edit source]A note under the parts list says no part numbers are given for anything on PCB30001, the board on the drive mechanism; a faulty board was to be returned to Amstrad with the whole mechanism for replacement.[1] The disc control circuit diagram on pages 35–36 of the manual is the schematic of that board and shows its capacitor values, for example C101 at 3.3 µF / 50 V. The drive board numbers its parts independently, so its C101 is not the main board's C101, a 0.1 µF ceramic.[4]
Before you start
[edit | edit source]- Amstrad's basic hardware analysis names no capacitor. For a dead machine it starts at the monitor's mains fuse and the lead from the monitor, then the computer's connectors, soldered joints and switch; disc faults go to the separate drive flow chart.[5] 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.
- See Capacitor Failure Symptoms and Recommended Tools.
Related pages
[edit | edit source]- Amstrad CPC 664 · Amstrad CPC 664 Maintenance Guide · Amstrad CPC 664 Troubleshooting Guide
- Amstrad CPC 464 Capacitor Replacement Guide
- Amstrad CPC 664 Service Manual
References
[edit | edit source]- ↑ 1.0 1.1 1.2 1.3 Amstrad Consumer Electronics plc, CPC664 Micro Computer / CTM644 Colour Monitor / GT65 Green Monitor Service Manual, p. 21 "Electrical Parts List CPC664" and pp. 16–18 "CPC664 Main PCB". Described at Amstrad CPC 664 Service Manual.
- ↑ Amstrad Consumer Electronics plc, CPC664 Micro Computer / CTM644 Colour Monitor / GT65 Green Monitor Service Manual, back page "CPC664 Technical Specification". Described at Amstrad CPC 664 Service Manual.
- ↑ 3.0 3.1 Amstrad Consumer Electronics plc, CPC664 Micro Computer / CTM644 Colour Monitor / GT65 Green Monitor Service Manual, pp. 19–20 "CPC664 C.P.U. Circuit Diagram" (C129 10V47 across the 5 V supply, C101–C128 0.1 µF decoupling) and p. 36 "Cassette Control Circuit Diagram" (C314 50V1 (NP), IC302 LA6358S). Described at Amstrad CPC 664 Service Manual.
- ↑ Amstrad Consumer Electronics plc, CPC664 Micro Computer / CTM644 Colour Monitor / GT65 Green Monitor Service Manual, pp. 35–36 "Disc Control Circuit Diagram". Described at Amstrad CPC 664 Service Manual.
- ↑ Amstrad Consumer Electronics plc, CPC664 Micro Computer / CTM644 Colour Monitor / GT65 Green Monitor Service Manual, p. 4 "CPC664 Basic Hardware Analysis" and pp. 8–11 "Diagnostic Flow Chart". Described at Amstrad CPC 664 Service Manual.