An Inexpensive CRT Tester for Your Thrifting Adventures

In case you haven’t heard: CRTs are back. They’re desirable for retrogaming, as most games were designed for CRT TVs until the mid-2000s. But nobody makes new CRTs, which means you’ll need to find a used unit. The problem is that many of those on FB Marketplace and in thrift stores are faulty. That’s why tube enthusiasts will want to build Nicholas Murray's affordable CRT tester for their thrifting adventures.

This is a pocket-friendly and battery-powered testing device built specifically for CRT monitors and TVs. It outputs a standard composite analog video signal, so it will be compatible with most CRT models. Some TVs only accept RF input and some monitors only accept VGA input, so this won’t work with those as it is. But the majority of desirable models will have a composite input.

Once assembled and flashed, this device will let you do tests to verify basic functionality. It will, of course, output a video signal to verify that the tube is working in the first place. But it also outputs different test patterns, so you can ensure that the colors show up correctly and there isn’t any unusual beam deflection.

To build this, all you’ll need is an M5Stack M5StickC Plus 2 development board, an M5Stack M5StickC Proto Hat, the custom PCB for this project, a couple of resistors, and an RCA jack (yellow, obviously). Depending on how you get the custom PCB, this tester could cost as little as $25 to make.

Then you simply flash the provided firmware and you’re ready to go. The M5StickC Plus 2 has a built-in lithium battery and charging circuit, so the only wire you need for testing is a composite video cable. Push the main button to switch between test patterns, which will show up on the CRT and the M5StickC Plus 2’s display. You can even swap between NTSC and PAL!