So I sent the device to a tech because I am to frustrated to go through a 2 month exchange process again.
He found that the playe voltage was set to around 700V, this was causing the low quality 6550s Fryette is installing to go into thermal runaway, even though 6550s can handle around 800V, these apparently can’t handle the 709V they are biased for.
When reducing the gird voltage to -38V, the tubes work again and the fuse doesn’t blow.
@Gil @dan @Team_Fryette can you send me replacement tubes, the unit is less than 2 months old
Thank you