During the yearly “RISC OS eXperience” event, organized by the Dutch Acorn and RISC OS user group “Big Ben Club”, we encountered a BBC Master with a broken PSU. The RIFA capacitors, as well as the startup capacitor had been replaced to no avail.

We discussed an alternative solution: replacing the PSU innards by a modern Mean Well PT-65A PSU module. Simon Inns documented the entire process on his website; model files for 3D printable brackets are available on his Github page.

To make purchasing components easier, I’m tracking down the manufacturer part numbers and added links to vendors that accept low volume orders. The total cost of materials is expected to be in the EUR 40-50 range per machine. Some parts have a minimum order size of 5-10 items, so it would be more cost-efficient to do a group buy. Note that this is a work in progress - more information will be added as needed.

Amount Product Vendor(s) Description
1 Mean Well PT-65A conrad.nl # 1294087 Power supply module, +12V / +5V / -5V
1 Molex 09501031 conrad.nl # 2446773 3-pin male connector housing, 3.96mm pitch
1 Molex 09501061 conrad.nl # 2446776 6-pin male connector housing, 3.96mm pitch
9 Molex 08701031 conrad.nl # 2901023 Crimp terminal
1 TE Crimp connector housing 1-640520-0 RS Components # 7099993 Aux power
(if rebuilding cable harness)
5 TE Crimp terminal 641294-1 RS Components # 7100545 Crimp terminal
(if rebuilding cable harness)
? Vogt Verbindungstechnik 3963S conrad.nl # 736837 Spade receptacle
(if rebuilding cable harness)

Other parts (t.b.d.):

  • 3D-printed brackets
  • Crimping tool
  • Various lengths of wire (0.5 mm2 / 20 AWG) in red, black and violet
  • 4x M3x12mm screws and nuts
  • 8x M3 Washers
  • 1x 10mm inner diameter rubber cable grommet