Editing Acorn Archimedes A4000 Troubleshooting Guide (section)

== Dead machine with power present ==

If the rails are good but the machine is dead, the fault is on the main PCB. Acorn's procedure is to inspect the board, then run the functional test software:<ref name="sm" />

* Check the ROMs are correctly seated with no lifted pins, and the configuration links '''LK10, LK11, LK12 and LK14'''.
* Because the ARM2, MEMC1a, VIDC1a and IOC are inside the ARM250, the bus-level checks used on the discrete-chip [[Acorn Archimedes A3000 Troubleshooting Guide|A3000]] (clock present, reset released, DRAM RAS/CAS, address lines incrementing under a held reset, data bus not stuck) apply here at the ARM250 pins and the RAM. If the clock, reset and rails are present but the ARM250 produces no bus activity, the ARM250 itself is the suspect &mdash; it is a whole-device replacement.
* As on the A3000, do not leave a board powered with no clock: loss of DRAM refresh can damage the RAM.