AD597 install and problem with Ultimaker 2+ thermocouple temperature

[tiaguera79 1]

Hi all! 

I have just installed the AD597 thermos amplifier and did all changing in Marlin so I could reach the 400+ Celsius degree...

the problem is that after doing so my readings are reaching as much as 125-135 degrees Celsius but the printer head reaches way higher temperatures. I have changed the original printer head for a two heads volcano model that reaches high temperatures.

I believe I am having trouble with the PID config or some Marlin detail.

please, If someone have had this problem and has any Idea on how I can fix it I would so much appreciate it.

 

tks in advance.

[andywalter 7]

Am not familiar with Marlin code, but as far as I can see, the AD597A uses a K-type thermocouple, and gives a reading of 1V at 100C, 2V at 200C etc up to 4V at 400C should be no problem, even up to 1200C providing the input supply voltage is at least 12V plus a bit. Farnell.com has a datasheet on the chip. This extract says

Since the output can only swing to within 2 V of the positive supply, the usable measurement temperature range will be restricted when positive supplies less than 15 V for the AD597...

. So if you give the chip a 5V supply, ti can only output at most a 3V signal corresponding to 300C. Suggest you check what voltage it's getting, and maybe give it 7V or even a bit more. Also make sure you're using a K-type thermocouple, not some thermistor or other J-ytpe or whatever TC.

 

I replaced a defective AD597A on my UMO, and in the process found that mine gets a 5V supply voltage. Enough for my ABS at 260C.