Low Bending Current

Error: Bending current at high energies, is too low (from approximately 100 Amp upwards). Cable to capacitors is getting warm. (Instable 2R current)

Likely one of the three thyristors in the bending power-supply is faulty. Measure with an oscilloscope the waveform before and after the choke. A missing phase is easily detected. The large AC component induces a large current through the capacitors, this is why the pink cabling gets warm. Look at drawing Z1-3.1A for information about waveforms under fault conditions.

Check the PCB's on the thyristors for bad contacts (soldering).

After replacing the thyristor, check if all three phases are equally loaded. Re-tune with the 10turn pots on control PCB's

It is a good idea to routinely 'feel' the warmth of the pink cable frequently during control sessions: gives a quick and good impression of the state of the thyristor blocks!