Editing Amstrad MP-1 / MP-2 Maintenance Guide

<templatestyles src="Template:StyledTable/styles.css" />
[[File:Amstrad MP-1.jpg|thumb|right|300px|An MP-1 with its three output leads and mains lead]]
The [[Amstrad MP-1]] and MP-2 are mains power supplies with a UHF modulator, used in place of an Amstrad monitor to run a [[Amstrad CPC 464]] or [[Amstrad 6128]] on a television. Amstrad's CPC service manuals cover the computers and monitors but not these units. The checks below come from the computer user manuals and service manuals: the leads, the supply checks and the faults that come from the setup.<ref name="ui464">Amstrad Consumer Electronics plc, ''CPC464 Colour Personal Computer'' user manual, retyped edition. Hosted as [[:File:Amstrad CPC 464 User Manual.pdf]], described at [[Amstrad CPC 464 User Manual]]. Safety notes (PDF p. 4); Foundations 1, section 1.3 (PDF pp. 11–12); section 1.1.3.</ref><ref name="ui6128">Amstrad, ''CPC6128 User Instructions'' (1985), Foundation Course chapter 1, pp. 1–5. Scan at [https://archive.org/details/amstrad-cpc-6128-user-manual archive.org]. Retrieved 2026-10-02.</ref>

== Safety ==

Warning: both units contain mains voltage. Unplug the mains lead before handling the leads or opening the case.

* Amstrad specifies a 5&nbsp;A fuse when a 13&nbsp;A (BS1363) plug is fitted to the mains lead.<ref name="ui464" /><ref name="ui6128" />
* The CPC 6128 manual quotes the rating label under the MP-2: "Warning – live parts inside. Do not remove any screws."<ref name="ui6128" />
* Amstrad asks owners not to block the ventilation slots of the power supply/modulator, to keep liquids away from it, and to disconnect the mains plug when it is not in use.<ref name="ui464" />

Amstrad did not publish a circuit diagram, parts list or safety test for the MP-1 or MP-2 in its CPC service manuals. For its other mains units it specifies a flash test and an insulation test of at least 4&nbsp;MΩ after servicing; the [[Amstrad DDI-1 Maintenance Guide]] gives the DDI-1's figures.<ref name="smddi">Amstrad Consumer Electronics plc, ''DDI1 / FD1 Service Manual'', p. 2, safety test. Described at [[Amstrad DDI-1 / FD-1 Service Manual]].</ref> Test an opened unit in the same way before using it again.

== Leads ==

{| class="wikitable styled-table" style="width:70%; text-align:left;"
|+'''Leads and where they go'''
! Lead !! Connects to
|-
| 6-pin DIN plug || Computer socket marked MONITOR
|-
| 5&nbsp;V DC plug || Computer socket marked 5V DC
|-
| Aerial plug || Television aerial socket
|-
| MP-2 rear socket || The CPC 6128's own 12&nbsp;V DC lead
|}

The DIN and DC leads on the MP-1 are coiled.<ref name="mp1photo">Manbemel, [https://commons.wikimedia.org/wiki/File:Amstrad_MP-1.jpg "Amstrad MP-1.jpg"], Wikimedia Commons, 2012 (CC BY-SA 3.0). Retrieved 2026-10-02. The unit, its label (MODULE MP-1) and its leads.</ref> Check each lead where it enters the case and at the plug, where repeated flexing breaks conductors, and clean the DIN and DC plugs if the picture or power is intermittent.

Amstrad's CPC 6128 circuit diagram marks the computer's 12&nbsp;V plug as inner ground and outer +12&nbsp;V.<ref name="sm6128">Amstrad Consumer Electronics plc, ''CPC6128 Service Manual'', circuit diagram, 12&nbsp;V lead polarity. Described at [[Amstrad CPC 6128 Service Manual]].</ref> Check any replacement supply for a CPC 6128 against that before connecting it.

== Checks ==

Amstrad's fault chart for a CPC 464 that will not power up starts at the supply: the mains fuse, then 5&nbsp;V DC on the cable from the supply, then the computer's own connectors and switch.<ref name="sm464">Amstrad Consumer Electronics plc, ''CPC464 Micro Computer / CTM640 Colour Monitor / GT64 Green Monitor Service Manual'', p. 9, basic hardware analysis. Described at [[Amstrad CPC 464 Service Manual]].</ref> The same order applies when an MP-1 or MP-2 is the supply.

{| class="wikitable styled-table" style="width:100%; text-align:left;"
|+'''Faults with an MP-1 or MP-2'''
! Symptom !! Probable cause !! Action
|-
| Red ON lamp on the computer does not light || Mains fuse in the plug, mains lead, 5&nbsp;V lead || Check the fuse, then measure 5&nbsp;V DC at the MP's DC plug; if present, follow the computer's own fault chart
|-
| Lamp lit, no picture || Television tuning, aerial lead, DIN lead || Tune a spare channel to about channel 36; check the aerial and DIN leads
|-
| 80-column text unclear || Normal with a modulator || Amstrad suggests mode 1 for text entry
|-
| Hiss from the television (CPC 464) || Normal; the CPC 464 has its own loudspeaker || Turn the television volume down
|-
| CPC 6128 starts but the disc drive does not work || 12&nbsp;V lead not plugged into the MP-2 || Plug the computer's 12&nbsp;V lead into the socket on the rear of the MP-2
|-
| Disc errors with a DDI-1 || Drive too close to the screen || Keep disc drives at least 20&nbsp;cm from the television or monitor
|}

The channel, the mode 2 note and the hiss note are from the CPC 464 manual; the 12&nbsp;V lead from the CPC 6128 manual; the 20&nbsp;cm spacing from the DDI-1 user instructions.<ref name="ui464" /><ref name="ui6128" /><ref name="uiddi">Amstrad Consumer Electronics plc (AMSOFT), ''Disc Drive & Interface DDI-1'' user instructions, © 1984, retyped edition, section F1.4. Hosted as [[:File:Amstrad DDI-1 User Instructions.pdf]], described at [[Amstrad DDI-1 User Instructions]].</ref>

== Cleaning ==

Unplug the unit and clean the case with a dry cloth. Amstrad's manual warns that liquid spilt into the power supply/modulator causes serious damage.<ref name="ui464" />

== Related pages ==

* [[Amstrad MP-1]] · [[Amstrad CPC 464]] · [[Amstrad 6128]]
* [[Amstrad CPC 464 Troubleshooting Guide]] · [[Amstrad CPC 6128 Troubleshooting Guide]]
* [[Amstrad DDI-1 Maintenance Guide]]

== References ==
<references />

{{Navbox-Amstrad|state=collapsed}}

[[Category:Amstrad]]
[[Category:Maintenance Guides]]