I concur, the handle of this model looks like the Atten 858D type hot air gun. I concur with ptrick too, I wouldn't be surprised if the firmware did not have such a failsafe function programmed.
I've never had to try this out but I wouldn't be surprised given the bad soldering encountered by the OP that the sense leads of the heating element to this unit were likely not connected/soldered.
FWIW, a name brand reworkstation will run near $1000, so getting something in the $100 range comes with big trade offs. I spent a week troubleshooting my unit before I even turned it on. It had some nasty assembly faults, but once fixed, its been working well.
As for runaway temps from a poor sensor and other newbie readers of this thread. First, if such a failure did occur, and a unit simply went to maximum regardless of a setting, it would not suddenly ramp to >600C instantly, so the user has some time to react. In evaluation 400+C is desperately hot, and can be sensed during the test phase when I got the unit by putting my hand about 1 foot from the smallest nozzle and move slowly toward the tip, the hotter it gets the farther you have to put your hand away to tolerate the heat. You can try melting eutectic solder or spot check the temp if not with a thermocouple.
Second, to burst into flames is strange, I think something is admist is the assembly again. The heater assembly is lined with ceramic, there is nothing to ignite inside the handle. However, the shaft of the heat gun did have a oily film I presume as a rust retardant or to make it appear shiny. When the unit is first used, the burning of this oily film gives the virign unit an odor than dissappears once the unit has been used. This oil can potentially ignite. Or if the user was using it around paper, the output of the gun past 480C could, at 6" or so, heat anything nearby to flame.
So word of warning to any 858D style owners out there, but it can be avoided by due diligence, that's the trade off between $100 and $1000 stations.
Interesting. Seems like a sensor burnout. Never heard of that one before
ouch.
Bad programming . Anything that controls temperature should default to room temp if the sensor reading either is wrong or not present. Sadly some firmware says things like "
if (current < target)
{
increasetemp();
}
if (current > target) {
lowertemp();
}
There is no handling of if the temp reads 0