Editing Acorn Archimedes A3000 Maintenance Guide (section)

== Power supply checks ==

With the mains hazard in mind, the only routine live measurement is the +5&nbsp;V rail (a DC voltmeter on the PSU output connector, lid open, mains live &mdash; take care):

<templatestyles src="Template:StyledTable/styles.css" />
{| class="wikitable styled-table" style="width:80%; text-align:center;"
|+'''A3000 PSU output (per Service Manual)'''
! Parameter !! Value
|-
| Output voltage (V01) || 4.9&ndash;5.1&nbsp;V (nominal 5&nbsp;V)
|-
| Output current || up to 4.4&nbsp;A
|-
| Ripple and noise || 50&nbsp;mV pk-pk (0&ndash;50&nbsp;MHz)
|-
| Over-voltage trip || 5.8&ndash;7.0&nbsp;V
|-
| Total output power || 22&nbsp;W continuous (29&nbsp;W surge)
|}

If the +5&nbsp;V is low, high or absent, or shows excessive ripple, the fault is in the PSU module. The Service Manual treats the PSU as a non-serviceable assembly; replacement or a careful recap (see [[Acorn Archimedes A3000 Capacitor Guide]]) are the options.