Push-Button Degaussing For An Arcade CRT

[Ed] was tasked with adding push-button degaussing to an arcade cabinet’s CRT console. The display can be rotated to portrait mode for games that require it, but each time this is done, the magnetic fields get out of whack.

Fortunately, the schematics arrived with the display. [Ed] found that the degauss coil is connected in series with a PTC fuse in an odd arrangement that he didn’t agree with. He decided to use an SSR to switch the coil, and after making lots of transistor-based designs on paper, grabbed a nearby Arduino.

[Ed] took off the PTC and soldered in two wires to its pads for the SSR. He added a wire to the power supply decoupling cap to power the new deguassing circuit and connected the SSR to the Arduino as an open collector input. There was just enough space available to mount the relay to the frame’s base and the Arduino on the side. [Ed] wrote a short method to trigger the SSR and reconnected the PTC fuse. Now it degausses at power up as well as on demand.