I'm betting on a wrong mains fuse value,
and unfortunately for OP the transformer successfully protected the fuse
Correct me if wrong but AFAIK a T-2A primary fuse has no hope of blowing out if the 120 volt 75 watt iron hits a 150 watt fault current and beyond, especially on a 240 volt zap
I'm guesstimating a 750ma to 1 amp fast blow glass fuse would glow and blow on a fault before the windings do,
or obliterate itself on a fault or 240 volt accident.
Someone didn't do their homework and or didn't have a pair of UNI-T or Aneng meters to measure currents (much less Fluke or EEVblog meters
)
and instead worked it out in their head
and released the product
I wonder just how much of this 'no fuse' or 'wrong fuse' fiasco has gone un-noticed over the years
Seriously, it's not rocket science to work out the correct value fuse,
and rig a unit to survive 120 volt and 240 volt zaps,
or even 440 volt 3 phase wiring stuffups
Behringer has been doing it for over 20 years on budget musician/recording gear.
They obviously prefer their customers to stay raw, uncooked, and in a healthy spending state,
with no 'firestarter' bad reputation for the company to think about
And how hard is it to glue/press/embed a temperature cutout switch on the primary windings in case they decide to simmer n smoke,
for -whatever- the reason?
What are some/all? soldering station manufacturers smoking?
Perhaps they should try their own lit up product fumes
at the next
Save A Silly Buck Bored Meeting... and get a clue