I need help determining which wires go to the heater and temperature sensor. connector: http://img218.imageshack.us/my.php?image=liitinrq7.jpg 1. yellow 2. red 3. white (I think this is the grounding) 4. blue 5. black I measured resistance between yellow and red to be 22.4 Ohms I also measured resistance between blue and black to be 1.2 Ohms Am I right assuming the higher resistance connection is the heater? The handle is made by Aoyue. Here are some pics of the heater: http://img183.imageshack.us/my.php?image=lammitin1md4.jpg http://img183.imageshack.us/my.php?image=lammitin2dn4.jpg http://img172.imageshack.us/my.php?image=lammitin3sx2.jpg http://img220.imageshack.us/my.php?image=lammitin4hk6.jpg http://img215.imageshack.us/my.php?image=lammitin5mk9.jpg http://img220.imageshack.us/my.php?image=lammitin6uz5.jpg
The 1.2 ohm connection is definitely the heater. With pretty much all soldering stations, the heater is low voltage, probably 10-30v (ac or dc will work, originally it was likely ac). It's likely that the 22.4 ohm resistance is the thermistor, or it could possibly (very unlikely) be a thermocouple, whigh uses a totally different system to measure temperature (outputs a specific voltage dependant on temperature). One pin should be connected to the metallic sleeve that contains the heater, and holds the tip. That would be a ground for ESD protection.
I did some more measurements and it appears that resistance doesn't change when warming the tip with a lightbulb. However betveen blue and black I could measure few tenths of a millivolt. From which I reached a conclusion that the handle has thermocouple. But thanks anyway.
Yes you're absolutely right. I don't know of any thermistors that would survive 400C. Thermocouples are almost always used and therefore this will be the lowest resistance. The 22.4 ohm resistance gives about 25W at 24V so that sounds reasonable. If it were the 1.2 ohm you'd end up with a 500W soldering iron
from the aoyue 936 soldering station instruction manual: 1 and 2 sensor (1.7-1.8 ohm normally) 4 and 5 heating element (16 - 18 ohm normally) 3 connected to the tip (esd protection) (under 2 ohm)
A warm thermocouple will also show a different value (on Resistance range) if you reverse the meter leads, as it's generating a small DC voltage that screws up the ohmic reading.
4 and 5 go to thermocouple because when I swapped the testleads the mV readout turned negative. 5 is positive and 4 negative.
Crap, you're right. Sorry, wasn't thinking straight. On the other hand, I wouldn't mind a 500w iron...
