... My 852D+ works well but your original message did make me realise that all was likely not as it appeared !
After reading this excellent thread I just had to join this forum so I could chip in my two cents.
I have a 230V Kada 852D+. It worked well for about a year, albeit with very little actual on time. Then, when I wasn't watching, the air gun glowed cherry red (the smell caught my attention) but before I could hit the switch there was a loud bang and that was the end of things whilst I waited for a replacement element from HK.
To cut a long story short I discovered the following:
The reason for the overheat was a spuriously firing triac; said triac (BTA08 I think) was no doubt annoyed by being driven in "bang-bang" mode by a non zero volt crossing optoisolator. (In the end I ripped out all the hot air circuitry and put my own design in.)
The air heater control circuit was driven from a zener at the end of a dropper chain from 230V. One dropper got so hot it had shed its cement coating. I suspect the design was just badly adapted from a 110V model.
There was no thermocouple failure or overheat protection.
The hot air element is not fused at all except at the wall plug.
As in the WEP, the Kada is only fused in the neutral line - totally useless.
My Kada was also totally unearthed; reason: paint around the earth anchor and incorrect type of screw.
Whilst calibrating the thing after making the necessary repairs I discovered that the thermocouple op amp gain preset was cranked hard against the endstop (you just know it's a wrong-un when that happens) so it was impossible to get the right temperature at the air nozzle -very annoying as it was surprisingly accurate (give or take 10?) before it blew up.
When I first got the Kada my impression was that it was pretty good for the money but having lifted the lid it is very poor and unsafe by UK standards. Shame really, given the same components it could have been designed in a much better and safer way.
I'm currently redesigning the whole thing with readouts that show actual iron and air temperatures (not just values from a dual-gang pot
) and a good sprinkling of protection circuits.
Quick plea for help: Anyone know the rated voltage/ current of the air pump in these things? I see its got a few cement droppers between it and the triac but there are no markings on the case that I can see. They are sold on eBay as K03 pumps but I cannot find any info about them.
Bob