This is an old scr model. It looks like it was made with some parts from Cesab. It has the typical 3 scr type circuit. A loose part in the machine fell against the choke coils and destroyed it taking out the turnoff scr and a resistor in the controller board. An attempt was made to make a coil to replace the choke but I have no way of knowing if it is anywhere near correct. The scr and resistor were replaced also.

The symptoms I have at the moment is the fwd or reverse contactors close but when the accelerator is pressed there is a "backfire", the contactors drop out and the wheels move a bit.

If I disconect the kathode of the turnoff scr from the snubber board there is a very slow commutation with little power.

I've been over and checked everything I can think of. The controller card is Cesab 104 FM/I.

Grateful for any advice