CRT mini PC (4in CRT with Pi 4)

A compact, all in one PC with a Pi 4 and 4in monochrome CRT. PETG is advisable for the body piece, as the pi 4 can run hot.

You will need:

• All printed parts (print in the provided orientation - window should be a single layer of transparent/translucent filament OR a single layer of 0 top/bottom layer and grid infill for a breathable mesh)

• Raspberry Pi 4

• AliExpress 4in CRT (if it's a 404, just search 4in CRT on aliexpress)

• USB-C PD trigger board capable of outputting 12v

• DC-DC voltage step down module/buck converter

• M3 screws, M2.5 screws, M3 4.2 outer diameter 4-5mm long threaded inserts

• Wire capable of handling 1.5A @ 12V peak - I used 20AWG PTFE wire

• USB-C plug to power the Pi

Assembly:

• Forewarning - CRTs are dangerous if you are not careful with them. The glass neck is delicate and if you break it, it will implode. They are also capable of storing a large amount of current, enough to seriously hurt you. Read up on CRT safety if you have not handled one before. This one is small and so it can't store as much current as a large TV but it can still give you a nasty shock!

• Set your PD trigger board to output 12v. Set the buck converter to output 5.1v.

• Wire up as follows. The CRT's datasheet is available here and the Pi 4's pinout and test points are widely documented.

• Test that it works and that you can get video! Mine would refuse to work without the brightness/contrast controls plugged in.

• Calibrate the display - refer to the CRT's datasheet for the potentiometer controls. It is NTSC, not PAL, so configure your Pi for it.

• Glue the window into place

• Put the electronics in place - I put the pi in first (remember to put the SD in too and configure it for analogue video out!) and then connect everything together where necessary. You'll need some glue to hold things down, hot glue works best

• Screw the sides on. I used clear nylon screws in mine because they look cool.