Editing Acorn A5000 Troubleshooting Guide (section)

== Dead computer with power present ==

If the rails are good but the machine is dead, the Service Manual's checks are:<ref name="sm" />

* Check the '''DRAM-size links''' are set correctly for the fitted memory (the combination of main-PCB DRAM and any RAM card must be a legal size &mdash; e.g. 4&nbsp;MB on the main PCB plus a RAM card is illegal). See the links appendix.
* Check the '''ZIP-package DRAM ICs''' are correctly seated in their sockets.
* Check the ROMs are correctly located and oriented with no lifted pins.
* Substitute the backplane and remove podules one at a time &mdash; a shorted podule or backplane can hold the machine down. Re-test with a known-good backplane.
* The main PCB is a replacement-only assembly; a board fault that survives the above is returned/replaced.

Because the ARM3, MEMC1a, VIDC1a and IOC are separate devices on the A5000, the bus-level checks used on the [[Acorn Archimedes A3000 Troubleshooting Guide|A3000]] (clock present, reset released, DRAM RAS/CAS, address lines toggling under a held reset, data bus not stuck) apply here using the [[Acorn A5000 Circuit Diagrams]]. As on every ARM2/ARM3 Archimedes, do not leave a board powered with no clock &mdash; the DRAM loses refresh.