when you're measuring the tip with the gun.. Make sure the tip is NOT shiny/ tinned..
Maybe put some rosin on it and let it turn black..
Because if it's shiny/reflective, the reading will be off by ALOT..
I'm amazed at how accurate this thing is as I've compared it with other thermometers and it's usually within +/- .1 degrees (we're talking earth temperature ranges). Anyways yes, it seems that reflective metals emit less infrared energy. I don't understand the physics of it, but this is a fact. However, isn't it true that a properly tinned tip will carry more heat to the surface than a badly oxidized surface? I have some blackened tips that I can try. However, I cannot get the tip hot enough to tin it properly anyway, although I have not tried turning it up to 450 or 500C.
Oh, my original 936 that would not power up, I found a short in the power PCB. It's all handmade and wired. When I get a chance I can bypass this part of the circuit. This was favorite station and it worked great. If I can get it working I'll just say "screw it" and use that one. If not I have a Radio Shack fixed temp that will work well enough for what I need. I don't need 500C, just 275 to 300C.
Edit: So with the blackened, rough tip I got a max temp of 175 degrees with the dial set to 300. Now this station is weird in that the power comes on and off to adjust the temperature. I thought that a station has a variable wattage to the handpiece depending on the setting? For example 10 to 60W. I'd be curious to see the wattage going to the iron. Some of the wiring may be done by hand, but the transformer is a drop-in piece, so I would think this should be correct. Anyways, is it safe to say that this thing is screwed, or may it simply be a calibration issue? I could not make out any calibration procedure in the manual.
Edit: That was pretty stupid. I switched over to Farenheit when I was playing with it. The max temperature on the tip surface with the non-tinned tip is 80C, virtually the same as the original handpiece and tip.