Hi. I'm having some problems with temperature stability.

3D Printing
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1

Hi. I’m having some problems with temperature stability. I just got the new E3D Cartridge blocks and a thermocouple and a Semitec thermistor (i have 2 extruders). I’m running on 24V and the heater is just too powerfull to handle full current (massive overshoots of 30-40°C), so i have BANG_MAX 100 in marlin. I did PID autotune a couple of times but as soon as i start the heater i get strange temperature readings on all sensors (also the ones that are not heated). The temperature curve is not smooth anymore but jumps +/- 2°C constantly on sensors where it should be constant.

I believe the BANG_MAX has something to do with it. When i have it set to full 255 i don’t get those deviations on disabled heaters, but 255 is just not usable on my machine.

Is there any truth in my theory? Even with PID tuned i can’t get stable temperatures because the sensors don’t read correctly.

EDIT: I will post a picture where all heaters are disabled and the difference it maked when i turn one ON after i finnish the current print.

EDIT 2: Tool 0 it a Thermocouple and Tool 1 is a Semitec 104-GT thermistor.

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2

Sounds like a power supply issue. What PSU and mainboard are you running?

3

Yeah I was thinking the same as Tom. Noise on your power supply or cables.

4

Megatronics 3.1 and the 24V 10A PSU from reprapworld (probably far eastern…)

5

After print is done, temps get stable and the T0 curve is steadily dropping. After turning T1 to 200C the jitter appears again, but this time not as bad as the 1st time.
missing/deleted image from Google+

6

My bet is also PSU. Did you change only block or cartridge also? Just a thought, maybe you’ve got 12V cartrige? Oh and cheap PSU tends to swing all over and do real mess when they hit the upper third of their stated power.

7

As Matej says, this looks like a distinct power issue (or lack of it) to me.