Question: It's been a while since I have soldered, so I bought a cheap unbranded soldering iron to use while I re-familiarised myself with the skill. After a few weeks of use, I turned it on just now and it popped with a blue spark. Now it appears to be dead. Did I do something wrong, or is that simply what happens sometimes when you buy a cheap soldering iron? I'm curious to find out what could have happened.

Ironically, just before the magic smoke escaped from the cheap one, I actually bought a new soldering station (Hakko FX-888D) earlier today, as I had a feeling it was time to get better equipment. Spooky. I guess the cheap one got upset and self-destructed.

Out of curiosity, I dismantled the dead soldering iron and took a photo of the board inside.

[![Dead soldering iron PCB](https://i.stack.imgur.com/JHrz8.jpg)](https://i.stack.imgur.com/JHrz8.jpg)

With my limited knowledge of electronics, my intuition tells me that an arc occurred between the AC wires. If so, is this bad luck, bad soldering, or user error?

[![Close up of the burnt AC wires](https://i.stack.imgur.com/aKqa0.jpg)](https://i.stack.imgur.com/aKqa0.jpg)

The insulation appears burned, but also the core of the wires seems to be a bit frayed. Was this as a result of the arc, or low quality manufacturing?

*Bonus question:* I wasn't touching the button at the time the iron popped, but if I was, would I have received an electric shock? Would it have been life threatening or painful?

*Edit:* I am in the UK (230VAC).

Answer: 
Just looking at how these wires are soldered to the PCB indicates a low quality product. I would not blame you but the product instead.
It looks like the mains cord was not fully soldered to the board.
-----------------------------------------------------------------

You can see a stray whisker of the ground still. There were probably also loose strands on the current-carying conductors. They probably flexed enough to touch when you were handling the cord, and when you plugged it in, they bridged a rush of current through and vaporized. POP!

I'm kind of surprised that it broke the iron. It shouldn't have. But whatever. I've been using $10 irons all my life and they work okay for me without any circuit board inside them. But that hakko is super great too, so enjoy it.