Cloos GLC 350N Control and wire feed fault

[Nix2]

Hello.
I have this fault in my Cloos GLC 350N machine with a separate feeder CK6x N (maybe CK66 N):

When I press the button on the handle, there is no wire feed at all, and the contactor and solenoid valves (42V AC) receive such 50Hz pulses that they "vibrate" and "rattle" at the mains frequency, making a lot of noise.
Has anyone repaired this control board and replaced the component (I think it's a triac FS12) responsible for activating the contactor and solenoid valve? This "triac" gets very hot, starting to burn out about 40 seconds after pressing the button.

Does anyone have a circuit board diagram for this Cloos?

This is the voltage at the 42V AC contactor terminals.
regards

 

[eddie49]

From what you have said about the noise, and looking at the 'scope trace, I think that "half" of the TRIAC is not going into conduction when triggered, so the "other half" is effectively acting as a half-wave rectifier. I am not sure if this failure method is possible, but it would explain the 50Hz buzzing noise.
I think this may be the TRIAC - "FS12 09" - rated at 800v and 12A:

Fagor Electronica FS1209NH TU, Thyristor 800V, 12A 15mA | RS

ie.rs-online.com