2x 48V 5A Bench Top Power Supply

This is a tutorial for assembling a bench top power supply. Don't expect any electronics development or lots of soldering, I just ordered some parts from AliExpress and put them in a box.

Please beware that I made some small adjustments on the published design so pictures might deviate slightly from what you'll be building.

Supplies

1x 10.5A 48V SMPS https://www.aliexpress.com/item/32905696401.html?s...

2x DC DPS5005 step-down converter https://www.aliexpress.com/item/32756513394.html?s...

1x IEC320 fused female power socket (AC-17) https://www.aliexpress.com/item/4000469723664.html...

2x chassis mounted terminal blocks https://www.aliexpress.com/item/32796082123.html?s...

4x female banana plug https://nl.rs-online.com/web/p/banana-connectors/1...

1x 12V 50x50mm quiet fan

1x 50x50mm finger guard https://www.aliexpress.com/item/4000104316790.html...

1x 45°C thermostat switch https://www.aliexpress.com/item/4000407678713.html...

4x rubber feet

Some M4 fasteners, some wagos, some wire and some faston terminals

Step 1: Laser Cut Panels

Cut 4mm wooden panels (or any material really).

IMPORTANT! The original design assumes a cutting width of 0.1mm. This is machine, material & panel thickness dependent and important if you want your panels to fit snugly. If you know the cutting width that is applicable for you, you can swap the original finger joints (based on a 0.1mm cutting width) with a new box design generated on makeabox.io (using your new cutting width). Internal box dimensions should be: WxHxD = 143 x x 219 x 95.5

Step 2: Make Corner Cubes

Depending on the panel thickness and type of insert you are using, you might want to adjust this piece. Currently based on 4mm panels and brass M4 inserts that require a 6mm hole in order to ensure a proper press fit.

Print it 4 times and press your brass inserts into the cubes. This should require some force. If not, you might want to redesign the cube or fixate the inserts using glue.

Step 3: Prep the SMPS

This SMPS already has active cooling but we'd like to cool not only the SMPS but also the step-down converters. Two fans would be a little ridiculous so remove the top cover of the original enclosure, which holds the cooling fan. We won't be mounting the cover back on but don't throw it away just yet as it contains the terminal labels required for wiring.

I used a new, smaller and quieter fan but if you want to recycle the one that came with the SMPS that's fine. Just remember to adjust your box design accordingly (the original fan is a little bigger).

In case of using a new (50mm) fan: cut (don't pull out) the fan cable leaving some cable length near the PCB connector and leave it sticking out of the PCB for now.

Step 4: Assemble the Box

Glue together all panels except for the top one, not forgetting about the corner cubes. These are impossible to assemble after the side panels have been joined.

IMPORTANT: ensure all panels (as they are shown in the file) are facing OUTWARDS when assembling the box.

IMPORTANT²: ensure that the BOTTOM PANEL HOLES are CLOSER to the BACK SIDE of the box than to the front side, as the SMPS will reside near the back.

IMPORTANT³: the PICTURES might be CONFUSING as they show a design where the top panel still has finger joints, which have been removed by now.

Step 5: Mount Components and Wire Everything Up

Wire everything up using common sense, no rocket engineering required. You'll see that the step-down converters have removable terminal blocks (or whatever those are called), very handy for mounting the converters into the panels later on.

I would suggest cranking up the output voltage of your SMPS (using the potmeter). The step-down converters apparently like to have some input headroom when outputting high voltages at high load.

Hook up your fan to the fan connector located on the SMPS PCB by soldering or using wagos (as I did). If you don't want to have your fan running all the time, you can put a thermal switch in between fan and PCB. Mount the fan as a final step; other wise it'll block the SMPS terminals.

Step 6: Assemble Top Cover and Rubber Feet

Please note I have a different design than the one available in this instructable. I removed the finger joints in the top panel as they are not required (corner cubes), impede easy removal if necessary and cause the front cover to be less robust near the step-down converters due to thin sections.

I considered mounting a handle on top but eventually didn't because I want my PS to be stackable.

Step 7: Testing

So far I've been able to use my PS with success but I did not test it at full load yet. To be updated.