Overview

We have here a replica of the Acorn Archimedes A3000 computer PCB. Unfortunately, a large percentage of A3000 PCBs have been eaten by the onboard battery which are highly prone to leakage.

So what have we done about it?

Over the period of a few years, I worked on replicating the A3000 PCB, but found it was no easy undertaking! Bringing on board some like-minded individuals affectionately named "The Board Folk", we worked together to get the schematics put in to Kicad and then trace the PCB layout. This has the added advantage of being able to check the schematics against the layout of the original PCB. The PCB is 4 layers. The internal layers are Power/GND planes, but also contains hidden traces that route around the outer right edge and bottom of the board.

Any enhancements?

Pre-populated SMD components

All SMD components are pre-populated, including sockets for the 4 PLCC ICs. The decision to do this was based on experience while testing earlier revisions. The PCB is extremely susceptible to warping when heated, and pretty much all test boards had this issue.

Added a test header

We added a 6-pin test header (LK99) to the PCB to allow connecting a "postbox" for testing. Github: Link

Filtered or unfiltered audio jumpers

We added extra jumper headers (LK91 and LK92) to choose if you want the audio filtered (as original), or unfiltered. This is a common modification that is often carried out to make the audio "brighter". Moving the jumpers is an easy way to help you decide how you'd prefer it.

Install 4MB directly to the board

We have included a jumper to select between 1MB on-board RAM (as original), or 4MB, using larger ZIP-RAM modules.

Flash ROM Support

We added a jumper header to allow the population of the ROM sockets with 39SF040 DIP32 flash ROMs in place of original masked ROMs. NB: You still need a RISCOS 3 license if you don't already own one for the board. Link: RISCOS

Supporting documents

The Bill of materials (BOM) can be found here: Acorn Archimedes A3000 BOM

Known issues

An issue was encountered during testing where a RAM expansion with specifically Goldstar branded RAM did not function correctly. This was never resolved after much troubleshooting. (The expansion works on an original PCB). NB: All other RAM expansions we tested worked flawlessly.