Sounds like the gas is right but not on/blocked or at too low a level to give coverage.
The tungsten doesn't go black from getting too hot, it just melts! ;)
...just to add, in general with the remote switch set to "off" the pedal will operate as a switch(working at whatever amp setting on the main dial), with it "on" it should give you variable amps.
(Don't pull the foot pedal to pieces just yet! ;) )
It sounds like you've got the foot pedal only operating as a switch rather than a rheostat.
Check operation with the remote switch in both positions and also check the connections at the bottom, in between the gas and torch, the remote will be the one with the arrow in the box and the p and q...
The AC frequency should be high enough to mean it doesn't matter! ;)
The cleaning action @ 15amps WILL be less than the cleaning action @ 150amps though.
If however your AC frequency was so low as to synch in with your pulse then you would have problems.
So for .8 sec. @ 50Hz you'll have 40...
Tighten the arc by upping the EN to as much as you can get away with and if it's got frequency control upping that too will help tighten the arc further.
8-12 litres a m.. is too much, 2-3 lpm after purge is established will be more than adequate and 75-85 amp is going to be too low as the 10mm flange will soon suck the heat out in that range.
I'm not familiar with that particular machine but with a scratch start you just have to whip the torch away. Just sounds like you're moving it too slowly.
How'd ya get the hole in the middle?
I can't quite see how having a hole through the middle of your electrode would help with welding, surely it would compromise the amps the electrode could handle, or do you get special doughnut/torus shaped welds? :waving:
Also a hypodermic needle is slash...