According to this fellow who lists a circuit-bent PSS-15 (same model as this but with a silver control panel), connecting part of the audio output to the keyboard matrix returns can re-trigger ...

When the chance arrived to buy a mechanical keyboard for not a lot, naturally, [Hales] jumped at it. Then it started having odd intermittent problems with some keys appearing stuck, which led to a ...

Figure 1 This circuit for a 4×3 keyboard shows a more efficient architecture using two CD4017 Johnson counters with only two I/O pins. The example described here showshow to implement this method to ...

establishing the matrix circuit required for the keypresses to register. It’s a remarkable redesign of some fairly basic keyboard components, all sitting on top of the LCD screen. The 65-percent ...