I'm using a TC-08 with 8 inputs, all type K.
ch 1 is about 800C, the others are about 11C
The readings are 250C for ch 1, 23-25 C for the other 7 channels.
If I disconnect ch1, all the other readings drop down to [the correct] 11C.
Additionally, sometimes, the readings all change to the correct ones. I haven't been able to determine a pattern for that effect.
Laptop is a PC.
Try electrically isolating the tip.
Technical Support Manager