Reflow oven: the temperature probe
First of all, let's meet the oven:
The oven is a Princess PR2259. It's a 4 liter oven with infared heaters totalling 660W. It is compact but still quite powerful which is good for fast heat changes. The oven comes with a small tray which may come in handy to spread the heat a little over the PCB.
Two IR heaters are present, on the top and on the bottom:
No fancy electronics are used in the oven, basically the heaters are connected through a four way switch (to turn elements on and off separately) and a mechanical timer with an annoying bell.
Thermocouple
The thermocouple is a wire made of two different metals that are joined at the tip. It is a standard K-type thermocouple:
I decided to keep most of the oven intact since it uses special screws and my el-cheapo screwdriver that fits them can break any minute now. Here is the left side of the oven opened:
A spring mechanism keeps the glass door shut when not opened manually and the two heaters are connected with heat resistant wires. The inside of the oven is attached to the sides by twisting it through short cuts in the side, as you can see below. This is a good place to place put the thermocouple wire through:
On the outside, the wire comes out at the back.
I have yet to take a picture of the thermocouple on the inside of the oven, I will put that here later. Next step is the solid state relay box.