One nice hot summer day a thunderstorm came and a lightning bolt struck near our neighbourhood network. The Ronja device was containing a flaw which made it susceptible to damage in such scenario. Fortunately this flaw is already believed to been fixed.
What happened is that the sensitive input transistor Q101 got broken through and started to make strong noise. The device stopped working.
Fortunately, Ronja is designed to be easily repairable. With consumer electronics such a case often leads to throwing away the whole device, which is an unnecessary burden for the Earth's ecosystem and the user's wallet and time. We tried to avoid this problem with the User Controlled Technology design of Ronja.
We performed testing procedures on the link which indicated the fault is in the receiver. Then we replaced the receiver with another piece and opened the old one. The receiver schematic (left) contains checkpoints which we measured and we saw the Q101 is damaged.
It cost us about 1 USD in material to replace the Q101 with a new one. Then the receiver was like new again.
Once I built a new receiver and made a mistake and omitted the output check. A resistor was wired into a wrong place. When I turned it on, the resistor was burnt into smoke. It was easy to replace it. Ronja is built from primitive building blocks. Apart from facilitating repairs, this approach also minimizes possibility of bugs. It's easy to have a bug in an Ethernet transceiver chip. It's difficult to make a bug in a transistor or a resistor ;-)