907A knockoff soldering handle voltage

[spleenharvester]

Hi all

Element just blew on my 907A knockoff handle. I've ordered a new one, but checked the voltage at the element and it's reading in as 30V AC. Is this enough to kill the element, it should be 24V right?

Cheers

[petehall347]

is that voltage unloaded ?

[redwire]

30VAC is about 25% high, which is typical for a cheap 24VAC power transformer with no load present. It also depends on if you have high mains voltage as well.
With the heater load it would sag down to ~24VAC, a transformer's voltage rating is under full load and they jump up a fair bit higher with no load. It's worse with lower quality/cheap transformers, or the chinese realizing the soldering iron heater is never on 100% of the time so they undersize the transformer in the first place. The smaller the transformer, the worse their regulation is. In the old days you over-designed and put in a real say 3A 75VA transformer which would be huge and have 15% regulation but nowadays price is all that matters, copper and steel are expensive.