main fuse & bais problem

[glennkaspar]

This happened with Both F5m and just now with F6. adjusting bias gently
then the Bias just runs away and blows the mains fuse, and with my F6
one Mosfet,

 

[Zen Mod]

more pictures
more text

 

[tjw59]

Knee jerk reaction is if the bias pots came out of the same bin, maybe a bad run of them?