Bill-counting machines kept going down because of a failing optical encoder sensor. Multiple machines went offline in a very short period of time.

The original board was hard to source. So instead of a one-off repair, we reverse-engineered the simple sensor board, designed a drop-in replacement PCB, 3D-printed a mounting bracket matching the original geometry, and produced a batch of 50 units — enough for the client to keep a spare-parts stock on hand and swap a failed unit in minutes instead of waiting on a discontinued part.

A few things that mattered more than expected:
- The mechanical fit of the 3D-printed bracket had to preserve the encoder's optical alignment.
- Designing for a 50-unit batch.
- Component sourcing matters for this project.

Full write-up with photos: https://github.com/DMC1988/2026719-1

#hardwaredesign #pcbdesign #reverseengineering #kicad #electronics