MEAN WELL QP-200-3A PSU Case

A case for the MEAN WELL QP-200-3A arcade power supply with voltmeters for +5v and +3.3v rails, and mounts for potentiometers to adjust the voltages (mod required to the PSU to wire those in). AC power is provided through a switched port on the side, and DC output is provided on the other side via a modular plug.

Note: I suspect this case will also work with the QP-150-3A, but it hasn't yet been verified. I'll update this once testing on that model is completed.

No special materials or settings needed, print it with the material or settings that you prefer. For my final print I used 60% infill to enhance rigidity but that isn't required.

Assembly instructions:

To mod the PSU, carefully remove the metal case. Find the two white potentiometers and de-solder them from the board and run wires from each of the six through holes to the replacement potentiometers.  The middle holes on each go to the middle pins on the potentiometers, the outer pads go to the outer pins on the potentiometer.  If you get the outer wires swapped the potentiometer will lower voltage as you turn the knob. If so just reverse the outer wires. Reassemble the case once complete, you may want to add a bit of thermal paste on the heatsinks to ensure a solid thermal connection.

The voltmeters just snap in, the white wires are the wires to connect to the voltage to measure, the red/black connect to +5v and ground.

The AC power socket snaps in, the lower pin is ground, and the others are neutral/live.

The DC power connector is a TE Connectivity AMP receptacle, it just snaps into the hole and the corresponding wires need to be run to the PSU screw terminals.  Here's the pinout that I used, but feel free to do it your own way if you prefer.

       ------- wires -------
      /    /    /    /    /
     /    /    /    /    /
   _________________________
  /                        /|
 /                        / |
/  4     3     2     1   /  |
-------------------------   |
| 3.3 | 3.3 | GND | GND |   |
------------------------|   |
| +5  | +5  | GND | GND |  /
------------------------| /
| 12  | -5  | GND | GND |/
-------------------------
 12    11    10     9

The potentiometers just slide through the holes. You may need to use a screwdriver to turn them to allow the thread to pass through. There was a small "key" on the potentiometers that I snipped off so they can sit flush against the case. Once tightened down with the nuts on the outer side they will be plenty secure without the key. Once they are tightened into the case you can align the knobs and tighten them down. Make sure they turn without rubbing on the case.

Parts list:

AC Power socket with switch (select model AC-05):
https://www.aliexpress.us/item/2251832775121714.html?spm=a2g0o.order_list.order_list_main.188.525f1802L5ojIP&gatewayAdapt=glo2usa

TE Connectivity AMP Connectors (Receptacle / Plug & Pins for each):
https://www.digikey.com/en/products/detail/te-connectivity-amp-connectors/176299-1/2328051
https://www.digikey.com/en/products/detail/te-connectivity-amp-connectors/176278-1/2328020
https://www.digikey.com/en/products/detail/te-connectivity-amp-connectors/175152-1/1149438
https://www.digikey.com/en/products/detail/te-connectivity-amp-connectors/175150-1/1152992

Mini 0.36 inch DC 0-30V digital voltmeter:
https://www.aliexpress.us/item/3256804577096703.html?spm=a2g0o.order_list.order_list_main.5.525f1802L5ojIP&gatewayAdapt=glo2usa

Potentiometers:
https://www.digikey.com/en/products/detail/bourns-inc/PDB181-E415K-102B/4699101

Knob for potentiometers:
https://www.digikey.com/en/products/detail/adafruit-industries-llc/5528/16653404