Boxing it up

A project log for Sort of 4th Axis

Rotary control of 4th axis on a mill to save time.

smashedagainstsmashedagainst 06/04/2015 at 19:110 Comments

I really like the design of the Samsung cheap laser printer we bought for front office's desk. It lasted longer than expected and when it eventually died, I took it apart to keep all the guts. The back of this PSU has a legend printed on the PCB of the connections with voltage and current. CON1 is the 115vac input. CON3 had 24V at 1.6 A and 5V at some other amps. CON3 is the small gray connector with lots of pins at the end away from the 115 input connector. CON2 is the white connector and supplies 115VAC to the high voltage power board.

I really appreciate how this PSU came with switch and IEC socket. I cut (well, machined) slots in the lower half of the case to hold these. The IEC's socket was designed for thin sheet metal, so I had to cut back the locking tabs and bend them out some to secure the socket in the case.

Red wire is soldered to the large pad underneath feeding 5V to the gray CON3. Green is soldered to the 24V pad. The black wires are soldered to the ground plane surrounding the DC section. This ground does not have continuity to the metal heatsinks nor either pin of the input 115V.

I placed clear acrylic plate above the PSU to keep my wires and the various 115V lines and connections away from the PSU's internals.

This highlights what I consider one of the bigger obstacles to small projects: connections between modules. I really like the 4 way screw terminal connection block. It has no exposed metal that can touch other bits and accommodates all wire sizes I use in projects. The output is trailer wiring, which is cable tied to the bottom of the case's battery holder. The psu uses a "trailer connector" and my project has the plug normally at the back of a car. While backwards-ish, I had only 1 "trailer" end and 2 "tow vehicle" ends, so thought this would allow the PSU to be used again.

Plus, the tow-side connector is available at many local stores, so it's easy to buy more. Second advantage to using the trailer wiring is how durable they are made; I can step on these wires without fear of damaging them.