Editing Amstrad CPC 664 Capacitor Replacement Guide (section)

== Main PCB Capacitors (Shared with the CPC 464) ==

The non-disc area of the CPC 664 main PCB inherits the CPC 464 capacitor positions. These are the per-IC decoupling (C104&ndash;C128), the AY-3-8912 sound output stage (C309/C311/C314/C315), the audio mixer (C307/C310/C313), the Z80 clock filter (C316) and the reset RC network (C302).

The CPC 464 cassette-area capacitors (C301, C303, C304, C306 on the cassette sub-PCB, plus C322 on the main PCB) are '''absent''' on the 664 because there is no cassette deck. The board layout in that area is reused for the audio mini-PCB.

<templatestyles src="Template:StyledTable/styles.css" />
{| class="wikitable styled-table" style="width:100%; text-align:center;"
|+'''CPC 664 main PCB &mdash; electrolytic capacitors (non-disc area)'''
! Designator !! Value !! Voltage !! Function
|-
| C101, C102 || 47 µF || 10 V || Sound output bypass
|-
| C309 || 1 µF || 50 V || AY-3-8912 channel A DC-block
|-
| C311 || 1 µF || 50 V || AY-3-8912 channel B DC-block
|-
| C314 || 1 µF || 50 V || AY-3-8912 channel C DC-block
|-
| C315 || 100 µF || 16 V || Audio output coupling
|-
| C301 (audio sub-PCB) || 100 µF || 10 V || LA4140 amp supply
|-
| C304 (audio sub-PCB) || 100 µF || 10 V || LA4140 output to speaker
|}

{| class="wikitable styled-table" style="width:100%; text-align:center;"
|+'''CPC 664 main PCB &mdash; ceramic capacitors (non-disc area)'''
! Designator !! Value !! Voltage !! Function
|-
| C104&ndash;C128 (one per IC) || 0.1 µF || 25 V || Per-IC supply decoupling
|-
| C307 || 470 pF || 50 V || Sound output ceramic coupling
|-
| C310 || 220 pF || 50 V || AY-3-8912 noise generator timing
|-
| C313 || 270 pF || 50 V || AY-3-8912 envelope timing
|-
| C316 || 33 pF || 50 V || Z80 clock filter
|}

{| class="wikitable styled-table" style="width:100%; text-align:center;"
|+'''CPC 664 main PCB &mdash; polystyrene capacitors'''
! Designator !! Value !! Function
|-
| C302 || 0.068 µF || Reset RC network
|}

The values, voltage and function map directly from the CPC 464 schematic. Where a 464 cap was in the cassette area, it is absent on the 664; where a 464 cap was in the system/audio area, it is present on the 664 with the same value.