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Nord Stage 3 External PSU Mod

PSU relocation done for Cameron Dobb in November 2023. Cameron wanted to play his lap-steel on top of his Nord, and the noise from the PSU was affecting his performance.





Design Challenges

The linear PSU inside the Stage 3 is quite large. Hammond #1455T2201RD fits it perfectly, with ample room for connectors, standoffs, and wiring, and comes in a Nord-ish red colour.







I opted for 4 pin aviation plugs and 4-conductor CNC cabling.


But that's a 12 pin power connector! They screamed.

The 12 pins are grouped in 4 sets of pins - +12V, -12V, +8V, and GND. Here's a map:




The unmarked pins are all ground.


Using the PSU itself as a template, it was trivial to mark mounting holes. I used m3 x 16mm screws and 7mm standoffs - nylon for the mains side and brass for the grounded secondary mounting holes.


I added my own fuse holder and power switch. The original switch was shorted with shunt wires just in case the switch ever opens in transit. This is the only modification done to the original PSU. In the original fuse holder, I fitted an over-sized fuse, and in the new fuse holder I fitted the original fuse value (0.33A).





Notes of Caution

The Nord Stage 3 PSU is UNGROUNDED - meaning the secondary is not referenced to earth ground at all. I mistakenly joined all grounds together (as is customary), and an obnoxious whine made it through to the outputs. Keep earth and ground separate, and do not earth the enclosure.


The length of cable seems to affect the bootup sequence. Likely, when the CPU boots it draws a huge amount of current, and the added inductance messes up the boot sequence. 30ft caused the Nord Stage 3 not to boot at all. 15ft let it boot, but the screen would cut in and out. 10ft seems to be the maximum. This may vary with thickness of cable and type of interconnects.






I designed some plugs to cover the holes left by the removal of the fuse and switch, and also an adapter to allow the aviation plug to fit in the AC cavity. I printed these in high-durability ABS. It's a good idea to keep dust and debris from getting inside.




STL Files here:

nordpsumod
.zip
Download ZIP • 19KB


All in all, a fairly challenging project. I wouldn't recommend it unless absolutely necessary.









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