Editing Amstrad CPC 464 Capacitor Replacement Guide (section)

== Main PCB Capacitors (CPC 464, Revisions 1&ndash;2) ==

The main PCB carries '''ten electrolytic''', '''eight ceramic''' (decoupling), '''three polystyrene''' (timing), and one '''ceramic''' on the AY-3-8912 sound output. Values and positions are taken directly from the service manual electrical parts list. Designators are with the IC101&ndash;IC125 main board reference scheme. Note: the C1xx range is main-board, the C3xx range is cassette sub-PCB.

<templatestyles src="Template:StyledTable/styles.css" />
{| class="wikitable styled-table" style="width:100%; text-align:center;"
|+'''CPC 464 main PCB &mdash; electrolytic capacitors'''
! Designator !! Value !! Voltage !! Function !! Service-manual part #
|-
| C101, C102 || 47 µF || 10 V || Sound output bypass at the audio amp side || 1400244
|-
| C308 || 22 µF || 10 V || Bypass on cassette input amp || 20025
|-
| C309 || 1 µF || 50 V || AY-3-8912 channel A DC-block || 20062
|-
| C311 || 1 µF || 50 V || AY-3-8912 channel B DC-block || 20062
|-
| C314 || 1 µF || 50 V || AY-3-8912 channel C DC-block || 20062
|-
| C315 || 100 µF || 16 V || Audio output coupling || 20028
|-
| C318 || 22 µF || 10 V || Bias bypass on the LA6324 cassette amp || 20025
|-
| C322 || 470 µF || 10 V || Cassette motor relay supply bypass &mdash; '''most-common failure''' || 1400248
|-
| C324 || 10 µF || 16 V || Cassette write-current shaping || 20024
|}

Note: C301, C303, C304, C306 (cassette sub-PCB electrolytics, values 100 µF/10 V and 47 µF/10 V respectively) are listed in the cassette sub-PCB table below.

{| class="wikitable styled-table" style="width:100%; text-align:center;"
|+'''CPC 464 main PCB &mdash; ceramic capacitors'''
! Designator !! Value !! Voltage !! Function
|-
| C104&ndash;C128 (25 caps) || 0.1 µF || 25 V || Per-IC supply decoupling. One cap across the VCC/GND pins of every IC on the main board
|-
| 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
|-
| C317, C319, C323 || 0.022 µF || 50 V || Cassette write-current shaping
|-
| C320 || 0.001 µF || 50 V || Cassette read filter
|-
| C321 || 200 pF || 50 V || Cassette read filter
|}

{| class="wikitable styled-table" style="width:100%; text-align:center;"
|+'''CPC 464 main PCB &mdash; polystyrene capacitors'''
! Designator !! Value !! Function
|-
| C302 || 0.068 µF || Reset RC network &mdash; sets the power-on reset pulse width
|-
| C305 || 0.01 µF || Cassette read low-pass filter
|-
| C312 || 0.001 µF || Cassette read 2 kHz tone shaping
|}

The 25 ceramic 0.1 µF decoupling caps (C104&ndash;C128) cover one cap per IC. The exact placement varies by board revision because the chip locations move &mdash; on Revision 3 (cost-down) boards with the 40226 combined ASIC, there are fewer ICs and therefore fewer decoupling caps.