Erbe ICC 350: startup error pointing to a pressed foot pedal
What happened
On power-up, the electrosurgical unit reported Error 22. According to the code interpretation this meant a foot pedal pressed at switch-on, although no pedal was pressed.
What was checked
- The CPU board was checked first and excluded as the source of the fault.
- The relay board was inspected; no obvious damage was visible from the outside.
- The schematic in the service documentation was compared with the actual board — the engineers found it did not match the real circuitry.
Cause
The engineers found the real cause on the relay board: a trace that had burned through while still looking intact, a failed 2.2 µF 50 V capacitor that had effectively turned into a resistor, and a damaged CD4050BE logic IC (values as reported in the case). The CPU board was not at fault.
What was done
Component-level repair of the relay board: the burned trace was restored, and the capacitor and the CD4050BE were replaced. After the repair the error no longer appeared and the unit was returned to service. The service manual in this case apparently described a different board revision, so the circuit was verified directly on the hardware.
Safety
Before opening the unit, disconnect it from the mains and let internal capacitors discharge; after any board repair on a patient-connected electrosurgical device, complete the electrical safety checks (protective earth continuity and leakage currents) before returning it to use.
Lesson: A pedal error code can point to any part of that signal path, not just the pedal — and when the service schematic does not match the actual board, trust the board and trace the circuit out yourself.
Covered in the course: Fault-Finding Method for Medical Equipment →
Written from an anonymised case shared by service engineers. It is not a manufacturer instruction and grants no authorisation. Independent note; names are trademarks of their owners.