Having problems with temperature readings (5 replies)

Hopefully someone can help me out here...

I have a Sanguinololu 1.3a board with 4.7k pullup resistors installed.
I have a J-Head hotend MK V-BV (the real deal, not a knockoff)

The hotend has a 104GT-2 thermistor installed.

The problem that I have is that it reads values, just not correctly.

For instance...
repetier host is set to: 255C
The Thermistor reads: 235C in Repetier
My meter says the temperature is 172C

I think my meter thermocouple is the most accurate considering it seems to follow the melt point of the plastic.

Any ideas why this could be so far off?

Thanks,
Jason