TeleKoRD MT Plus: generator does not start at power-on
What happened
On switching the unit on, a fault is reported and the generator refuses to start; suspicion fell on the generator Supply Board.
What was checked
- The engineers confirmed the fault appeared on every power-up attempt of the generator.
- Measured the supply rail at test point TP2 on the Supply Board: about 21 V reported instead of the expected ~27 V.
- The undervoltage was traced back to the primary of transformer T2: the incoming mains supply was low.
Cause
Reported cause: low facility mains voltage. With insufficient voltage at the primary of transformer T2, the Supply Board supply rail sat at about 21 V at TP2 instead of ~27 V, so the board registered undervoltage and blocked the generator start.
The cause is probable and was not fully confirmed.
What was done
The reported fix was to install an additional adjustable power supply unit (reported as a TDK Lambda type), powered from connector J2 (pins 1 and 4) of the Supply Board and feeding the board supply input via connector J10 (pins 2 and 8), with the output trimmed until TP2 read the nominal voltage. This is a hardware workaround for a weak mains supply, not a board repair; the outcome was reported as probable, and the low mains condition itself should be addressed at the facility side.
Safety
Before opening the generator, isolate the unit from the mains and allow the storage capacitors to discharge, and after any change to Supply Board wiring run a full electrical safety check, including protective earth, before the unit returns to clinical use.
Lesson: Before condemning a generator board, measure the incoming mains and the board supply test points — an undervoltage far upstream can look exactly like an electronics fault.
Covered in the course: X-ray Service — Level 2: Fault-Finding →
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.